Quelltext der Seite Aeronautics History Vivian 1920 02 Evolution of the Aeroplane Age of the Giants

{{Werk
|Titel=History of Aeronautics
|Autor=Vivian-Charles-E
|Copyright=Siehe eLib Lizenzen
|Auflage=1
|Entstehungsjahr=1920
|Erscheinungsjahr=1920
|Sprache=English
|Version=1
|Typ=Monographie
|Kurzbeschreibung=Geschichte der Luftfahrt bis 1920.
|ISBN=1414217021
|ISBN13=9781414217024
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|Wikilink=Aeronautics_History_-_Charles_Vivian_-_1920
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}}
:A History of Aeronautics 
:by E. Charles Vivian
:1920

==VI. THE AGE OF THE   GIANTS==

Until the Wright Brothers definitely solved the problem of
flight and virtually gave the aeroplane its present place in
aeronautics, there were three definite schools of experiment. 
The first of these was that which sought to imitate nature by
means of the ornithopter or flapping-wing machines directly
imitative of bird flight; the second school was that which
believed in the helicopter or lifting screw; the third and
eventually successful school is that which followed up the
principle enunciated by Cayley, that of opposing a plane surface
to the resistance of the air by supplying suitable motive power
to drive it at the requisite angle for support.

Engineering problems generally go to prove that too close an
imitation of nature in her forms of recipro-cating motion is not
advantageous; it is impossible to copy the minutiae of a bird's
wing effectively, and the bird in flight depends on the tiniest
details of its feathers just as much as on the general principle
on which the whole wing is constructed.  Bird flight, however,
has attracted many experimenters, including even Lilienthal;
among others may be mentioned F. W. Brearey, who invented what
he called the 'Pectoral cord,' which stored energy on each
upstroke of the artificial wing; E. P. Frost; Major R. Moore,
and especially Hureau de Villeneuve, a most enthusiastic student
of this form of flight, who began his experiments about 1865,
and altogether designed and made nearly 300 artificial birds.
one of his later constructions was a machine in bird form with a
wing span of about 50 ft.; the motive power for this was
supplied by steam from a boiler which, being stationary on the
ground, was connected by a length of hose to the machine.  De
Villeneuve, turning on steam for his first trial, obtained
sufficient power to make the wings beat very forcibly; with the
inventor on the machine the latter rose several feet into the
air, whereupon de Villeneuve grew nervous  and turned off the
steam supply.  The machine fell to the earth, breaking one of
its wings, and it does not appear that de Villeneuve troubled to
reconstruct it.  This experiment remains as the greatest success
yet achieved by any machine constructed on the ornithopter
principle.

It may be that, as forecasted by the prophet Wells, the
flapping-wing machine will yet come to its own and compete with
the aeroplane in efficiency.  Against this, however, are the
practical advantages of the rotary mechanism of the aeroplane
propeller as compared with the movement of a bird's wing, which,
according to Marey, moves in a figure of eight.  The force
derived from a propeller is of necessity continual, while it is
equally obvious that that derived from a flapping movement is
intermittent, and, in the recovery of a wing after completion of
one stroke for the next, there is necessarily a certain
cessation, if not loss, of power.

The matter of experiment along any lines in connection with
aviation is primarily one of hard cash. Throughout the whole
history of flight up to the outbreak of the European war
development has been handicapped on the score of finance, and,
since the arrival of the aeroplane, both ornithopter and
helicopter schools have been handicapped by this consideration.
Thus serious study of the efficiency of wings in imitation of
those of the living bird has not been carried to a point that
might win success for this method of propulsion.  Even Wilbur
Wright studied this subject and propounded certain theories,
while a later and possibly more scientific student, F. W.
Lanchester, has also contributed empirical conclusions.  Another
and earlier student was Lawrence Hargrave, who made a
wing-propelled model which achieved successful flight, and in
1885 was exhibited before the Royal Society of New South Wales.
Hargrave called the principle on which his propeller worked that
of a 'Trochoided plane'; it was, in effect, similar to the
feathering of an oar.

Hargrave, to diverge for a brief while from the machine to the
man, was one who, although he achieved nothing worthy of special
remark, contributed a great deal of painstaking work to the
science of flight.  He made a series of experiments with
man-lifting kites in addition to making a study of flapping-wing
flight.  It cannot be said that he set forth any new principle;
his work was mainly imitative, but at the same time by
developing ideas originated in great measure by others he helped
toward the solution of the problem.

Attempts at flight on the helicopter principle consist in the
work of De la Landelle and others already mentioned.  The
possibility of flight by this method is modified by a very
definite disadvantage of which lovers of the helicopter seem to
take little account.  It is always claimed for a machine of this
type that it possesses great advantages both in rising and in
landing, since, if it were effective, it would obviously be able
to rise from and alight on any ground capable of containing its
own bulk; a further advantage claimed is that the helicopter
would be able to remain stationary in the air, maintaining
itself in any position by the vertical lift of its propeller.

These potential assets do not take into consideration the fact
that efficiency is required not only in rising, landing, and
remaining stationary in the air, but also in actual flight.  It
must be evident that if a certain amount of the motive force is
used in maintaining the machine off the ground, that amount of
force is missing from the total of horizontal driving power. 
Again, it is often assumed by advocates of this form of flight
that the rapidity of climb of the helicopter would be far
greater than that of the driven plane; this view overlooks the
fact that the maintenance of aerodynamic support would claim the
greater part of the engine-power; the rate of ascent would be
governed by the amount of power that could be developed surplus
to that required for maintenance.

This is best explained by actual figures:  assuming that a
propeller 15 ft. in diameter is used, almost 50 horse-power
would be required to get an upward lift of 1,000 pounds; this
amount of horse-power would be continually absorbed in
maintaining the machine in the air at any given level; for
actual lift from one level to another at a speed of eleven feet
per second a further 20 horse-power would be required, which
means that 70 horse-power must be constantly provided for; this
absorption of power in the mere maintenance of aero-dynamic
support is a permanent drawback.

The attraction of the helicopter lies, probably, in the ease
with which flight is demonstrated by means of models constructed
on this principle, but one truism with regard to the principles
of flight is that the problems change remarkably, and often
unexpectedly, with the size of the machine constructed for
experiment.  Berriman, in a brief but very interesting manual
entitled Principles of Flight, assumed that 'there is a
significant dimension of which the effective area is an
expression of the second power, while the weight became an
expression of the third power.  Then once again we have the
two-thirds power law militating against the successful
construction of large helicopters, on the ground that the
essential weight increases disproportionately fast to the
effective area.  From a consideration of the structural features
of propellers it is evident that this particular relationship
does not apply in practice, but it seems reasonable that some
such governing factor should exist as an explanation of the
apparent failure of all full-sized machines that have been
constructed.  Among models there is nothing more strikingly
successful than the toy helicopter, in which the essential
weight is so small compared with the effective area.'

De la Landelle's work, already mentioned, was carried on a few
years later by another Frenchman, Castel, who constructed a
machine with eight propellers arranged in two fours and driven
by a compressed air motor or engine.  The model with which
Castel experimented had a total weight of only 49 lbs.; it rose
in the air and smashed itself by driving against a wall, and the
inventor does not seem to have proceeded further. Contemporary
with Castel was Professor Forlanini, whose design was for a
machine very similar to de la Landelle's, with two superposed
screws.  This machine ranks as the second on the helicopter
principle to achieve flight; it remained in the air for no less
than the third of a minute in one of its trials.

Later experimenters in this direction were Kress, a German;
Professor Wellner, an Austrian; and W. R. Kimball, an American. 
Kress, like most Germans, set to the development of an idea
which others had originated; he followed de la Landelle and
Forlanini by fitting two superposed propellers revolving in
opposite directions, and with this machine he achieved good
results as regards horse-power to weight; Kimball, it appears,
did not get beyond the rubber-driven model stage, and any
success he may have achieved was modified by the theory
enunciated by Berriman and quoted above.

Comparing these two schools of thought, the helicopter and
bird-flight schools, it appears that the latter has the greater
chance of eventual success--that is, if either should ever come
into competition with the aeroplane as effective means of
flight.  So far, the aeroplane holds the field, but the whole
science of flight is so new and so full of unexpected
developments that this is no reason for assuming that other
means may not give equal effect, when money and brains are
diverted from the driven plane to a closer imitation of natural
flight.

Reverting from non-success to success, from consideration of the
two methods mentioned above to the direction in which practical
flight has been achieved, it is to be noted that between the
time of Le Bris, Stringfellow, and their contemporaries, and the
nineties of last century, there was much plodding work carried
out with little visible result, more especially so far as
English students were concerned.  Among the incidents of those
years is one of the most pathetic tragedies in the whole history
of aviation, that of Alphonse Penaud, who, in his thirty years
of life, condensed the experience of his predecessors and
combined it with his own genius to state in a published patent
what the aeroplane of to-day should be.  Consider the following
abstract of Penaud's design as published in his patent of 1876,
and comparison of this with the aeroplane that now exists will
show very few divergences except for those forced on the
inventor by the fact that the internal combustion engine had not
then developed.  The double surfaced planes were to be built
with wooden ribs and arranged with a slight dihedral angle;
there was to be a large aspect ratio and the wings were cambered
as in Stringfellow's later models.  Provision was made for
warping the wings while in flight, and the trailing edges were
so designed as to be capable of upward twist while the machine
was in the air.  The planes were to be placed above the car, and
provision was even made for a glass wind-screen to give
protection to the pilot during flight.  Steering was to be
accomplished by means of lateral and vertical planes forming a
tail; these controlled by a single lever corresponding to the
'joy stick' of the present day plane.

Penaud conceived this machine as driven by two propellers;
alternatively these could be driven by petrol or steam-fed
motor, and the centre of gravity of the machine while in flight
was in the front fifth of the wings. Penaud estimated from 20 to
30 horse-power sufficient to drive this machine, weighing with
pilot and passenger 2,600 lbs., through the air at a speed of 60
miles an hour, with the wings set at an angle of  incidence of
two degrees.  So complete was the design that it even included
instruments, consisting of an aneroid, pressure indicator, an
anemometer, a compass, and a level.  There, with few
alterations, is the aeroplane as we know it--and Penaud was
twenty-seven when his patent was published.

For three years longer he worked, experimenting with models,
contributing essays and other valuable data to French papers on
the subject of aeronautics.  His gains were ill health, poverty,
and neglect, and at the age of thirty a pistol shot put an end
to what had promised to be one of the most brilliant careers in
all the history of flight.

Two years before the publication of Penaud's patent Thomas Moy
experimented at the Crystal Palace with a twin-propelled
aeroplane, steam driven, which seems to have failed mainly
because the internal combustion engine had not yet come to give
sufficient power for weight.  Moy anchored his machine to a pole
running on a prepared circular track; his engine weighed 80 lbs. 
and, developing only three horse-power, gave him a speed of
12 miles an hour.  He himself estimated that the machine would
not rise until he could get a speed of 35 miles an hour, and his
estimate was correct.  Two six-bladed propellers were placed
side by side between the two main planes of the machine, which
was supported on a triangular wheeled undercarriage and steered
by fairly conventional tail planes.  Moy realised that he could
not get sufficient power to achieve flight, but he went on
experimenting in various directions, and left much data
concerning his experiments which has not yet been deemed worthy
of publication, but which still contains a mass of information
that is of practical utility, embodying as it does a vast amount
of painstaking work.

Penaud and Moy were followed by Goupil, a Frenchman, who, in
place of attempting to fit a motor to an aeroplane, experimented
by making the wind his motor.  He anchored his machine to the
ground, allowing it two feet of lift, and merely waited for a
wind to come along and lift it.  The machine was stream lined,
and the wings, curving as in the early German patterns of war
aeroplanes, gave a total lifting surface of about 290 sq. ft.
Anchored to the ground and facing a wind of 19 feet per second,
Goupil's machine lifted its own weight and that of two men as
well to the limit of its anchorage.  Although this took place as
late as 1883 the inventor went no further in practical work.  He
published a book, however, entitled La Locomotion Aerienne,
which is still of great importance, more especially on the
subject of inherent stability.

In 1884 came the first patents of Horatio Phillips, whose work
lay mainly in the direction of investigation into the curvature
of plane surfaces, with a view to obtaining the greatest amount
of support.  Phillips was one of the first to treat the problem
of curvature of planes as a matter for scientific experiment,
and, great as has been the development of the driven plane in
the 36 years that have passed since he began, there is still
room for investigation into the subject which he studied so
persistently and with such valuable result.

At this point it may be noted that, with the solitary exception
of Le Bris, practically every student of flight had so far set
about constructing the means of launching humanity into the air
without any attempt at ascertaining the nature and peculiarities
of the sustaining medium.  The attitude of experimenters in
general might be compared to that of a man who from boyhood had
grown up away from open water, and, at the first sight of an
expanse of water, set to work to construct a boat with a vague
idea that, since wood would float, only sufficient power was
required to make him an efficient navigator.  Accident, perhaps,
in the shape of lack of means of procuring driving power, drove
Le Bris to the form of experiment which he actually carried out;
it remained for the later years of the nineteenth century to
produce men who were content to ascertain the nature of the
support the air would afford before attempting to drive
themselves through it.

Of the age in which these men lived and worked, giving their all
in many cases to the science they loved, even to life itself, it
may be said with truth that 'there were giants on the earth in
those days,' as far as aeronautics is in question.  It was an
age of giants who lived and dared and died, venturing into
uncharted space, knowing nothing of its dangers, giving, as a
man gives to his mistress, without stint and for the joy of the
giving.  The science of to-day, compared with the glimmerings
that were in that age of the giants, is a fixed and certain
thing; the problems of to-day are minor problems, for the great
major problem vanished in solution when the Wright Brothers made
their first ascent.  In that age of the giants was evolved the
flying man, the new type in human species which found full
expression and came to full development in the days of the war,
achieving feats of daring and endurance which leave the
commonplace landsman staggered at thought of that of which his
fellows prove themselves capable.  He is a new type, this flying
man, a being of self-forgetfulness; of such was Lilienthal, of
such was Pilcher; of such in later days were Farman, Bleriot,
Hamel, Rolls, and their fellows; great names that will live for
as long as man flies, adventurers equally with those of the
spacious days of Elizabeth.  To each of these came the call, and
he worked and dared and passed, having, perhaps, advanced one
little step in the long march that has led toward the perfecting
of flight.

It is not yet twenty years since man first flew, but into that
twenty years have been compressed a century or so of progress,
while, in the two decades that preceded it, was compressed still
more.  We have only to recall and recount the work of four men: 
Lilienthal, Langley, Pilcher, and Clement Ader to see the
immense stride that was made between the time when Penaud pulled
a trigger for the last time and the Wright Brothers first left
the earth.  Into those two decades was compressed the
investigation that meant knowledge of the qualities of the air,
together with the development of the one prime mover that
rendered flight a possibility--the internal combustion engine. 
The coming and progress of this latter is a thing apart, to be
detailed separately; for the present we are concerned with the
evolution of the driven plane, and with it the evolution of that
daring being, the flying man.  The two are inseparable, for the
men gave themselves to their art; the story of Lilienthal's life
and death is the story of his work; the story of Pilcher's work
is that of his life and death.

Considering the flying man as he appeared in the war period,
there entered into his composition a new element--patriotism--
which brought about a modification of the type, or, perhaps, made
it appear that certain men belonged to the type who in reality
were commonplace mortals, animated, under normal conditions, by
normal motives, but driven by the stress of the time to take rank
with the last expression of human energy, the flying type. 
However that may be, what may be termed the mathematising of
aeronautics has rendered the type itself evanescent; your pilot
of to-day knows his craft, once he is trained, much in the manner
that a driver of a motor-lorry knows his vehicle; design has been
systematised, capabilities have been tabulated; camber, dihedral
angle, aspect ratio, engine power, and plane surface, are
business items of drawing office and machine shop; there is room
for enterprise, for genius, and for skill; once and again there
is room for daring, as in the first Atlantic flight.  Yet that
again was a thing of mathematical calculation and petrol storage,
allied to a certain stark courage which may be found even in
landsmen.  For the ventures into the unknown, the limit of
daring, the work for work's sake, with the almost certainty that
the final reward was death, we must look back to the age of the
giants, the age when flying was not a business, but romance.



==VII. LILIENTHAL AND  PILCHER==

There was never a more enthusiastic and consistent student of
the problems of flight than Otto Lilienthal, who was born in
1848 at Anklam, Pomerania, and even from his early school-days
dreamed and planned the conquest of the air.  His practical
experiments began when, at the age of thirteen, he and his
brother Gustav made wings consisting of wooden framework covered
with linen, which Otto attached to his arms, and then ran
downhill flapping them.  In consequence of possible derision on
the part of other boys, Otto confined these experiments for the
most part to moonlit nights, and gained from them some idea of
the resistance offered by flat surfaces to the air.  It was in
1867 that the two brothers began really practical work,
experimenting with wings which, from their design, indicate some
knowledge of Besnier and the history of his gliding experiments;
these wings the brothers fastened to their backs, moving them
with their legs after the fashion of one attempting to swim. 
Before they had achieved any real success in gliding the
Franco-German war came as an interruption; both brothers served
in this campaign, resuming their experiments in 1871 at the
conclusion of hostilities.

The experiments made by the brothers previous to the war had
convinced Otto that previous experimenters in gliding flight had
failed through reliance on empirical conclusions or else through
incomplete observation on their own part, mostly of bird flight. 
From 1871 onward Otto Lilenthal (Gustav's interest in the
problem was not maintained as was his brother's) made what is
probably the most detailed and accurate series of observations
that has ever been made with regard to the properties of curved
wing surfaces.  So far as could be done, Lilienthal tabulated
the amount of air resistance offered to a bird's wing,
ascertaining that the curve is necessary to flight, as offering
far more resistance than a flat surface.  Cayley, and others,
had already stated this, but to Lilienthal belongs the honour of
being first to put the statement to effective proof--he made
over 2,000 gliding flights between 1891 and the regrettable end
of his experiments; his practical conclusions are still regarded
as part of the accepted theory of students of flight.  In 1889
he published a work on the subject of gliding flight which
stands as data for investigators, and, on the conclusions
embodied in this work, he began to build his gliders and
practice what he had preached, turning from experiment with
models to wings that he could use.

It was in the summer of 1891 that he built his first glider of
rods of peeled willow, over which was stretched strong cotton
fabric; with this, which had a supporting surface of about 100
square feet, Otto Lilienthal launched himself in the air from a
spring board, making glides which, at first of only a few feet,
gradually lengthened.  As his experience of the supporting
qualities of the air progressed he gradually altered his designs
until, when Pilcher visited him in the spring of 1895, he
experimented with a glider, roughly made of peeled willow rods
and cotton fabric, having an area of 150 square feet and
weighing half a hundredweight.  By this time Lilienthal had
moved from his springboard to a conical artificial hill which he
had had thrown up on level ground at Grosse Lichterfelde, near
Berlin.  This hill was made with earth taken from the
excavations incurred in constructing a canal, and had a cave
inside in which Lilienthal stored his machines.  Pilcher, in his
paper on 'Gliding,' [*] gives an excellent short summary of
Lilienthal's experiments, from which the following extracts are
taken:--

[*] Aeronautical Classes, No. 5.  Royal Aeronautical Society's
publications. 

'At first Lilienthal used to experiment by jumping off a
springboard with a good run.  Then he took to practicing on some
hills close to Berlin.  In the summer of 1892 he built a
flat-roofed hut on the summit of a hill, from the top of which
he used to jump, trying, of course, to soar as far as possible
before landing.... One of the great dangers with a soaring
machine is losing forward speed, inclining the machine too much
down in front, and coming down head first.  Lilienthal was the
first to introduce the system of handling a machine in the air
merely by moving his weight about in the machine; he always
rested only on his elbows or on his elbows and shoulders....

'In 1892 a canal was being cut, close to where Lilienthal lived,
in the suburbs of Berlin, and with the surplus earth Lilienthal
had a special hill thrown up to fly from.  The country round is
as flat as the sea, and there is not a house or tree near it to
make the wind unsteady, so this was an ideal practicing ground;
for practicing on natural hills is generally rendered very
difficult by shifty and gusty winds.... This hill is 50 feet
high, and conical.  Inside the hill there is a cave for the
machines to be kept in.... When Lilienthal made a good flight he
used to land 300 feet from the centre of the hill, having come
down at an angle of 1 in 6; but his best flights have been at an
angle of about 1 in 10.

'If it is calm, one must run a few steps down the hill, holding
the machine as far back on oneself as possible, when the air
will gradually support one, and one slides off the hill into the
air.  If there is any wind, one should face it at starting; to
try to start with a side wind is most unpleasant.  It is
possible after a great deal of practice to turn in the air, and
fairly quickly.  This is accomplished by throwing one's weight
to one side, and thus lowering the machine on that side towards
which one wants to turn. Birds do the same thing-- crows and
gulls show it very clearly.  Last year Lilienthal chiefly
experimented with double-surfaced machines.  These were very
much like the old machines with awnings spread above them.

'The object of making these double-surfaced machines was to get
more surface without increasing the length and width of the
machine.  This, of course, it does, but I personally object to
any machine in which the wing surface is high above the weight. 
I consider that it makes the machine very difficult to handle in
bad weather, as a puff of wind striking the surface, high above
one, has a great tendency to heel the machine over.

'Herr Lilienthal kindly allowed me to sail down his hill in one
of these double-surfaced machines last June. With the great
facility afforded by his conical hill the machine was handy
enough; but I am afraid I should not be able to manage one at
all in the squally districts I have had to practice in over
here.

'Herr Lilienthal came to grief through deserting his old method
of balancing.  In order to control his tipping movements more
rapidly he attached a line from his horizontal rudder to his
head, so that when he moved his head forward it would lift the
rudder and tip the machine up in front, and vice versa.  He was
practicing this on some natural hills outside Berlin, and he
apparently got muddled with the two motions, and, in trying to
regain speed after he had, through a lull in the wind, come to
rest in the air, let the machine get too far down in front, came
down head first and was killed.'

Then in another passage Pilcher enunciates what is the true
value of such experiments as Lilienthal--and, subsequently, he
himself--made:  'The object of experimenting with soaring
machines,' he says, 'is to enable one to have practice in
starting and alighting and controlling a machine in the air. 
They cannot possibly float horizontally in the air for any
length of time, but to keep going must necessarily lose in
elevation.  They are excellent schooling machines, and that is
all they are meant to be, until power, in the shape of an engine
working a screw propeller, or an engine working wings to drive
the machine forward, is added; then a person who is used to
soaring down a hill with a simple soaring machine will be able
to fly with comparative safety.  One can best compare them to
bicycles having no cranks, but on which one could learn to
balance by coming down an incline.'

It was in 1895 that Lilienthal passed from experiment with the
monoplane type of glider to the construction of a biplane glider
which, according to his own account, gave better results than
his previous machines.  'Six or seven metres velocity of wind,'
he says, 'sufficed to enable the sailing surface of 18 square
metres to carry me almost horizontally against the wind from the
top of my hill without any starting jump.  If the wind is
stronger I allow myself to be simply lifted from the point of
the hill and to sail slowly towards the wind.  The direction of
the flight has, with strong wind, a strong upwards tendency.  I
often reach positions in the air which are much higher than my
starting point.  At the climax of such a line of flight I
sometimes come to a standstill for some time, so that I am
enabled while floating to speak with the gentlemen who wish to
photograph me, regarding the best position for the
photographing.'

Lilienthal's work did not end with simple gliding, though he did
not live to achieve machine-driven flight.  Having, as he
considered, gained sufficient experience with gliders, he
constructed a power-driven machine which weighed altogether
about 90 lbs., and this was thoroughly tested.  The extremities
of its wings were made to flap, and the driving power was
obtained from a cylinder of compressed carbonic acid gas,
released through a hand-operated valve which, Lilienthal
anticipated, would keep the machine in the air for four minutes. 
There were certain minor accidents to the mechanism, which
delayed the trial flights, and on the day that Lilienthal had
determined to make his trial he made a long gliding flight with
a view to testing a new form of rudder that--as Pilcher
relates--was worked by movements of his head.  His death came
about through the causes that Pilcher states; he fell from a
height of 50 feet, breaking his spine, and the next day he died.

It may be said that Lilienthal accomplished as much as any one
of the great pioneers of flying.  As brilliant in his
conceptions as da Vinci had been in his, and as conscientious a
worker as Borelli, he laid the foundations on which Pilcher,
Chanute, and Professor Montgomery were able to build to such
good purpose.  His book on bird flight, published in 1889, with
the authorship credited both to Otto and his brother Gustav, is
regarded as epoch-making; his gliding experiments are no less
entitled to this description.

In England Lilienthal's work was carried on by Percy Sinclair
Pilcher, who, born in 1866, completed six years' service in the
British Navy by the time that he was nineteen, and then went
through a course of engineering, subsequently joining Maxim in
his experimental work.  It was not until 1895 that he began
to build the first of the series of gliders with which he earned
his plane among the pioneers of flight.  Probably the best
account of Pilcher's work is that given in the Aeronautical
Classics issued by the Royal Aeronautical Society, from which
the following account of Pilcher's work is mainly abstracted.[*]

[*] Aeronautical Classes, No. 5. Royal  Aeronautical Society
publications. 

The 'Bat,' as Pilcher named his first glider, was a monoplane
which he completed before he paid his visit to Lilienthal in
1895.  Concerning this Pilcher stated that he purposely finished
his own machine before going to see Lilienthal, so as to get the
greatest advantage from any original ideas he might have; he was
not able to make any trials with this machine, however, until
after witnessing Lilienthal's experiments and making several
glides in the biplane glider which Lilienthal constructed.


The wings of the 'Bat' formed a pronounced dihedral angle; the
tips being raised 4 feet above the body.  The spars forming the
entering edges of the wings crossed each other in the centre and
were lashed to opposite sides of the triangle that served as a
mast for the stay-wires that guyed the wings.  The four ribs of
each wing, enclosed in pockets in the fabric, radiated fanwise
from the centre, and were each stayed by three steel piano-wires
to the top of the triangular mast, and similarly to its base. 
These ribs were bolted down to the triangle at their roots, and
could be easily folded back on to the body when the glider was
not in use.  A small fixed vertical surface was carried in the
rear.  The framework and ribs were made entirely of Riga pine;
the surface fabric was nainsook.  The area of the machine was
150 square feet; its weight 45 lbs.; so that in flight, with
Pilcher's weight of 145 lbs. added, it carried one and a half
pounds to the square foot.

Pilcher's first glides, which he carried out on a grass hill on
the banks of the Clyde near Cardross, gave little result, owing
to the exaggerated dihedral angle of the wings, and the absence
of a horizontal tail.  The 'Bat 'was consequently reconstructed
with a horizontal tail plane added to the vertical one, and with
the wings lowered so that the tips were only six inches above
the level of the body.  The machine now gave far better results;
on the first glide into a head wind Pilcher rose to a height of
twelve feet and remained in the the air for a third of a minute;
in the second attempt a rope was used to tow the glider, which
rose to twenty feet and did not come to earth again until nearly
a minute had passed.  With experience Pilcher was able to
lengthen his glide and improve his balance, but the dropped wing
tips made landing difficult, and there were many breakages.

In consequence of this Pilcher built a second glider which he
named the 'Beetle,' because, as he said, it looked like one.  In
this the square-cut wings formed almost a continuous plane,
rigidly fixed to the central body, which consisted of a shaped
girder.  These wings were built up of five transverse bamboo
spars, with two shaped ribs running from fore to aft of each
wing, and were stayed overhead to a couple of masts.  The tail,
consisting of two discs placed crosswise (the horizontal one
alone being movable), was carried high up in the rear. With the
exception of the wing-spars, the whole framework was built of
white pine.  The wings in this machine were actually on a higher
level than the operator's head; the centre of gravity was,
consequently, very low, a fact which, according to Pilcher's own
account, made the glider very difficult to handle. Moreover, the
weight of the 'Beetle,' 80 lbs., was considerable; the body had
been very solidly built to enable it to carry the engine which
Pilcher was then contemplating; so that the glider carried some
225 lbs.  with its area of 170 square feet--too great a mass for
a single man to handle with comfort.

It was in the spring of 1896 that Pilcher built his third
glider, the 'Gull,' with 300 square feet of area and a weight of
55 lbs.  The size of this machine rendered it unsuitable for
experiment in any but very calm weather, and it incurred such
damage when experiments were made in a breeze that Pilcher found
it necessary to build a fourth, which he named the 'Hawk.'  This
machine was very soundly built, being constructed of bamboo,
with the exception of the two main transverse beams.  The wings
were attached to two vertical masts, 7 feet high, and 8 feet
apart, joined at their summits and their centres by two wooden
beams.  Each wing had nine bamboo ribs, radiating from its mast,
which was situated at a distance of 2 feet 6 inches from the
forward edge of the wing.  Each rib was rigidly stayed at the
top of the mast by three tie-wires, and by a similar number to
the bottom of the mast, by which means the curve of each wing
was maintained uniformly.  The tail was formed of a triangular
horizontal surface to which was affixed a triangular vertical
surface, and was carried from the body on a high bamboo mast,
which was also stayed from the masts by means of steel wires,
but only on its upper surface, and it was the snapping of one of
these guy wires which caused the collapse of the tail support
and brought about the fatal end of Pilcher's experiments.  In
flight, Pilcher's head, shoulders, and the greater part of his
chest projected above the wings.  He took up his position by
passing his head and shoulders through the top aperture formed
between the two wings, and resting his forearms on the
longitudinal body members.  A very simple form of undercarriage,
which took the weight off the glider on the ground, was fitted,
consisting of two bamboo rods with wheels suspended on steel
springs.

Balance and steering were effected, apart from the high degree
of inherent stability afforded by the tail, as in the case of
Lilienthal's glider, by altering the position of the body.  With
this machine Pilcher made some twelve glides at Eynsford in Kent
in the summer of 1896, and as he progressed he increased the
length of his glides, and also handled the machine more easily,
both in the air and in landing.  He was occupied with plans for
fitting an engine and propeller to the 'Hawk,' but, in these
early days of the internal combustion engine, was unable to get
one light enough for his purpose.  There were rumours of an
engine weighing 15 lbs.  which gave 1 horse-power, and was
reported to be in existence in America, but it could not be
traced.

In the spring of 1897 Pilcher took up his gliding experiments
again, obtaining what was probably the best of his glides on
June 19th, when he alighted after a perfectly balanced glide of
over 250 yards in length, having crossed a valley at a
considerable height.  From his various experiments he concluded
that once the machine was launched in the air an engine of, at
most, 3 horse-power would suffice for the maintenance of
horizontal flight, but he had to allow for the additional weight
of the engine and propeller, and taking into account the
comparative inefficiency of the propeller, he planned for an
engine of 4 horse-power.  Engine and propeller together were
estimated at under 44 lbs. weight, the engine was to be fitted
in front of the operator, and by means of an overhead shaft was
to operate the propeller situated in rear of the wings.  1898
went by while this engine was under construction.  Then in 1899
Pilcher became interested in Lawrence Hargrave's soaring kites,
with which he carried out experiments during the summer of 1899. 
It is believed that he intended to incorporate a number of these
kites in a new machine, a triplane, of which the fragments
remaining are hardly sufficient to reconstitute the complete
glider.  This new machine was never given a trial.  For on
September 30th, 1899, at Stamford Hall, Market Harborough,
Pilcher agreed to give a demonstration of gliding flight, but
owing to the unfavourable weather he decided to postpone the
trial of the new machine and to experiment with the 'Hawk,'
which was intended to rise from a level field, towed by a line
passing over a tackle drawn by two horses.  At the first trial
the machine rose easily, but the tow-line snapped when it was
well clear of the ground, and the glider descended, weighed down
through being sodden with rain.  Pilcher resolved on a second
trial, in which the glider again rose easily to about thirty
feet, when one of the guy wires of the tail broke, and the tail
collapsed; the machine fell to the ground, turning over, and
Pilcher was unconscious when he was freed from the wreckage.

Hopes were entertained of his recovery, but he died on Monday,
October 2nd, 1899, aged only thirty-four.  His work in the cause
of flying lasted only four years, but in that time his actual
accomplishments were sufficient to place his name beside that of
Lilienthal, with whom he ranks as one of the greatest exponents
of gliding flight.



==VIII. AMERICAN GLIDING EXPERIMENTS==

While Pilcher was carrying on Lilienthal's work in England, the
great German had also a follower in America; one Octave Chanute,
who, in one of the statements which he has left on the subject
of his experiments acknowledges forty years' interest in the
problem of flight, did more to develop the glider in America
than--with the possible exception of Montgomery--any other man. 
Chanute had all the practicality of an American; he began his
work, so far as actual gliding was concerned, with a full-sized
glider of the Lilienthal type, just before Lilienthal  was
killed. In a rather rare monograph, entitled Experiments in
Flying, Chanute states that he found the Lilienthal glider
hazardous and decided to test the value of an idea of his own;
in this he followed the same general method, but reversed the
principle upon which Lilienthal had depended for maintaining his
equilibrium in the air.  Lilienthal had shifted the weight of
his body, under immovable wings, as fast and as far as the
sustaining pressure varied under his surfaces; this shifting was
mainly done by moving the feet, as the actions required were
small except when alighting.  Chanute's idea was to have the
operator remain seated in the machine in the air, and to
intervene only to steer or to alight; moving mechanism was
provided to adjust the wings automatically in order to restore
balance when necessary.

Chanute realised that experiments with models were of little
use; in order to be fully instructive, these experiments should
be made with a full-sized machine which carried its operator,
for models seldom fly twice alike in the open air, and no
relation can be gained from them of the divergent air currents
which they have experienced.  Chanute's idea was that any flying
machine which might be constructed must be able to operate in a
wind; hence the necessity for an operator to report upon what
occurred in flight, and to acquire practical experience of the
work of the human factor in imitation of bird flight.  From this
point of view he conducted his own experiments; it must be noted
that he was over sixty years of age when he began, and, being no
longer sufficiently young and active to perform any but short
and insignificant glides, the courage of the man becomes all the
more noteworthy; he set to work to evolve the state required by
the problem of stability, and without any expectation of
advancing to the construction of a flying machine which might be
of commercial value.  His main idea was the testing of devices
to secure equilibrium; for this purpose he employed assistants
to carry out the practical work, where he himself was unable to
supply the necessary physical energy.

Together with his assistants he found a suitable place for
experiments among the sandhills on the shore of Lake Michigan,
about thirty miles eastward from Chicago.  Here a hill about
ninety-five feet high was selected as a point from which
Chanute's gliders could set off; in practice, it was found that
the best observation was to be obtained from short glides at
low speed, and, consequently, a hill which was only sixty-one
feet above the shore of the lake was employed for the
experimental work done by the party.

In the years 1896 and 1897, with parties of from four to six
persons, five full-sized gliders were tried out, and from these
two distinct types were evolved:  of these one was a machine
consisting of five tiers of wings and a steering tail, and the
other was of the biplane type; Chanute believed these to be
safer than any other machine previously evolved, solving, as he
states in his monograph, the problem of inherent equilibrium as
fully as this could be done.  Unfortunately, very few
photographs were taken of the work in the first year, but one
view of a multiple wing-glider survives, showing the machine in
flight.  In 1897 a series of photographs was taken exhibiting
the consecutive phases of a single flight; this series of
photographs represents the experience gained in a total of about
one thousand glides, but the point of view was varied so as to
exhibit the consecutive phases of one single flight.

The experience gained is best told in Chanute's own words.  'The
first thing,' he says, 'which we discovered practically was that
the wind flowing up a hill-side is not a steadily-flowing
current like that of a river.  It comes as a rolling mass, full
of tumultuous whirls and eddies, like those issuing from a
chimney; and they strike the apparatus with constantly varying
force and direction, sometimes withdrawing support when most
needed.  It has long been known, through instrumental
observations, that the wind is constantly changing in force and
direction; but it needed the experience of an operator afloat on
a gliding machine to realise that this all proceeded from
cyclonic action; so that more was learned in this respect in a
week than had previously been acquired by several years of
experiments with models.  There was a pair of eagles, living in
the top of a dead tree about two miles from our tent, that came
almost daily to show us how such wind effects are overcome and
utilised.  The birds swept in circles overhead on pulseless
wings, and rose high up in the air.  Occasionally there was a
side-rocking motion, as of a ship rolling at sea, and then the
birds rocked back to an even keel; but although we thought the
action was clearly automatic, and were willing to learn, our
teachers were too far off to show us just how it was done, and
we had to experiment for ourselves.'

Chanute provided his multiple glider with a seat, but, since
each glide only occupied between eight and twelve seconds, there
was little possibility of the operator seating himself.  With
the multiple glider a pair of horizontal bars provided rest for
the arms, and beyond these was a pair of vertical bars which the
operator grasped with his hands; beyond this, the operator was
in no way attached to the machine.  He took, at the most, four
running steps into the wind, which launched him in the air, and
thereupon he sailed into the wind on a generally descending
course.  In the matter of descent Chanute observed the sparrow
and decided to imitate it.  'When the latter,' he says,
'approaches the street, he throws his body back, tilts his
outspread wings nearly square to the course, and on the cushion
of air thus encountered he stops his speed and drops lightly to
the ground.  So do all birds.  We tried it with misgivings, but
found it perfectly effective.  The soft sand was a great
advantage, and even when the experts were racing there was not a
single sprained ankle.'

With the multiple winged glider some two to three hundred glides
were made without any accident either to the man or to the
machine, and the action was found so effective, the principle so
sound, that full plans were published for the benefit of any
experimenters who might wish to improve on this apparatus.  The
American Aeronautical Annual for 1897 contains these plans;
Chanute confessed that some movement on the part of the operator
was still required to control the machine, but it was only a
seventh or a sixth part of the movement required for control of
the Lilienthal type.

Chanute waxed enthusiastic over the possibilities of gliding,
concerning which he remarks that 'There is no more delightful
sensation than that of gliding through the air.  All the
faculties are on the alert, and the motion is astonishingly
smooth and elastic.  The machine responds instantly to the
slightest movement of the operator; the air rushes by one's
ears; the trees and bushes flit away underneath, and the landing
comes all too quickly.  Skating, sliding, and bicycling are not
to be compared for a moment to aerial conveyance, in which,
perhaps, zest is added by the spice of danger.  For it must be
distinctly understood that there is constant danger in such
preliminary experiments.  When this hazard has been eliminated
by further evolution, gliding will become a most popular sport.'

Later experiments proved that the biplane type of glider gave
better results than the rather cumbrous model consisting of five
tiers of planes.  Longer and more numerous glides, to the number
of seven to eight hundred, were obtained, the rate of descent
being about one in six.  The longest distance traversed was
about 120 yards, but Chanute had dreams of starting from a hill
about 200 feet high, which would have given him gliding flights
of 1,200 feet.  He remarked that 'In consequence of the speed
gained by running, the initial stage of the flight is nearly
horizontal, and it is thrilling to see the operator pass from
thirty to forty feet overhead, steering his machine, undulating
his course, and struggling with the wind-gusts which whistle
through the guy wires.  The automatic mechanism restores the
angle of advance when compromised by variations of the breeze;
but when these come from one side and tilt the apparatus, the
weight has to be shifted to right the machine... these gusts
sometimes raise the machine from ten to twenty feet vertically,
and sometimes they strike the apparatus from above, causing it
to descend suddenly.  When sailing near the ground, these
vicissitudes can be counteracted by movements of the body from
three to four inches; but this has to be done instantly, for
neither wings nor gravity will wait on meditation.  At a height
of three hundred or four hundred feet the regulating mechanism
would probably take care of these wind-gusts, as it does, in
fact, for their minor variations.  The speed of the machine is
generally about seventeen miles an hour over the ground, and
from twenty-two to thirty miles an hour relative to the air.
Constant effort was directed to keep down the velocity, which
was at times fifty-two miles an hour.  This is the purpose of
the starting and gliding against the wind, which thus furnishes
an initial velocity without there being undue speed at the
landing.  The highest wind we dared to experiment in blew at
thirty-one miles an hour; when the wind was stronger, we waited
and watched the birds.'

Chanute details an amusing little incident which occurred in the
course of experiment with the biplane glider.  He says that 'We
had taken one of the machines to the top of the hill, and loaded
its lower wings with sand to hold it while we e went to lunch. 
A gull came strolling inland, and flapped full-winged to
inspect.  He swept several circles above the machine, stretched
his neck, gave a squawk and went off.  Presently he returned
with eleven other gulls, and they seemed to hold a conclave
about one hundred feet above the big new white bird which they
had discovered on the sand.  They circled round after round, and
once in a while there was a series of loud peeps, like those of
a rusty gate, as if in conference, with sudden flutterings, as
if a terrifying suggestion had been made.  The bolder birds
occasionally swooped downwards to inspect the monster more
closely; they twisted their heads around to bring first one eye
and then the other to bear, and then they rose again.  After
some seven or eight minutes of this performance, they evidently
concluded either that the stranger was too formidable to tackle,
if alive, or that he was not good to eat, if dead, and they flew
off to resume fishing, for the weak point about a bird is his
stomach.'

The gliders were found so stable, more especially the biplane
form, that in the end Chanute permitted amateurs to make trials
under guidance, and throughout the whole series of experiments
not a single accident occurred. Chanute came to the conclusion
that any young, quick, and handy man could master a gliding
machine almost as soon as he could get the hang of a bicycle,
although the penalty for any mistake would be much more severe.

At the conclusion of his experiments he decided that neither the
multiple plane nor the biplane type of glider was sufficiently
perfected for the application of motive power.  In spite of the
amount of automatic stability that he had obtained he considered
that there was yet more to be done, and he therefore advised
that every possible method of securing stability and safety
should be tested, first with models, and then with full-sized
machines; designers, he said, should make a point of practice in
order to make sure of the action, to proportion and adjust the
parts of their machine, and to eliminate hidden defects.
Experimental flight, he suggested, should be tried over water,
in order to break any accidental fall; when a series of
experiments had proved the stability of a glider, it would then
be time to apply motive power.  He admitted that such a process
would be both costly and slow, but, he said, that 'it greatly
diminished the chance of those accidents which bring a whole
line of investigation into contempt.' He saw the flying machine
as what it has, in fact, been; a child of evolution, carried on
step by step by one investigator after another, through the
stages of doubt and perplexity which lie behind the realm of
possibility, beyond which is the present day stage of actual
performance and promise of ultimate success and triumph over the
earlier, more cumbrous, and slower forms of the transport that
we know.

Chanute's monograph, from which the foregoing notes have been
comprised, was written soon after the conclusion of his series
of experiments.  He does not appear to have gone in for further
practical work, but to have studied the subject from a
theoretical view-point and with great attention to the work done
by others.  In a paper contributed in 1900 to the American
Independent, he remarks that 'Flying machines promise better
results as to speed, but yet will be of limited commercial
application.  They may carry mails and reach other inaccessible
places, but they cannot compete with railroads as carriers of
passengers or freight.  They will not fill the heavens with
commerce, abolish custom houses, or revolutionise the world, for
they will be expensive for the loads which they can carry, and
subject to too many weather contingencies.  Success is, however,
probable.  Each experimenter has added something to previous
knowledge which his successors can avail of.  It now seems
likely that two forms of flying machines, a sporting type and an
exploration type, will be gradually evolved within one or two
generations, but the evolution will be costly and slow, and must
be carried on by well-equipped and thoroughly informed
scientific men; for the casual inventor, who relies upon one or
two happy inspirations, will have no chance of success
whatever.'

Follows Professor John J. Montgomery, who, in the true American
spirit, describes his own experiments so well that nobody can
possibly do it better.  His account of his work was given first
of all in the American Journal, Aeronautics, in January, 1909,
and thence transcribed in the English paper of the same name in
May, 1910, and that account is here copied word for word.  It
may, however, be noted first that as far back as 1860, when
Montgomery was only a boy, he was attracted to the study of
aeronautical problems, and in 1883 he built his first machine,
which was of the flapping-wing ornithopter type, and which
showed its designer, with only one experiment, that he must
design some other form of machine if he wished to attain to a
successful flight.  Chanute details how, in 1884 and 1885
Montgomery built three gliders, demonstrating the value of
curved surfaces.  With the first of these gliders Montgomery
copied the wing of a seagull; with the second he proved that a
flat surface was virtually useless, and with the third he
pivoted his wings as in the Antoinette type of power-propelled
aeroplane, proving to his own satisfaction that success lay in
this direction.  His own account of the gliding flights carried
out under his direction is here set forth, being the best
description of his work that can be obtained:--

'When I commenced practical demonstration in my work with
aeroplanes I had before me three points; first, equilibrium;
second, complete control; and third, long continued or soaring
flight.  In starting I constructed and tested three sets of
models, each in advance of the other in regard to the
continuance of their soaring powers, but all equally perfect as
to equilibrium and control.  These models were tested by
dropping them from a cable stretched between two mountain tops,
with various loads, adjustments and positions.  And it made no
difference whether the models were dropped upside down or any
other conceivable position, they always found their equilibrium
immediately and glided safely to earth.

'Then I constructed a large machine patterned after the first
model, and with the assistance of three cowboy friends
personally made a number of flights in the steep mountains near
San Juan (a hundred miles distant).  In making these flights I
simply took the aeroplane and made a running jump.  These tests
were discontinued after I put my foot into a squirrel hole in
landing and hurt my leg.

'The following year I commenced the work on a larger scale, by
engaging aeronauts to ride my aeroplane dropped from balloons. 
During this work I used five hot-air balloons and one gas
balloon, five or six aeroplanes, three riders--Maloney, Wilkie,
and Defolco--and had sixteen applicants on my list, and had a
training station to prepare any when I needed them.

'Exhibitions were given in Santa Cruz, San Jose, Santa Clara,
Oaklands, and Sacramento.  The flights that were made, instead
of being haphazard affairs, were in the order of safety and
development.  In the first flight of an aeronaut the aeroplane
was so arranged that the rider had little liberty of action,
consequently he could make only a limited flight.  In some of
the first flights, the aeroplane did little more than settle in
the air.  But as the rider gained experience in each successive
flight I changed the adjustments, giving him more liberty of
action, so he could obtain longer flights and more varied
movements in the flights.  But in none of the flights did I have
the adjustments so that the riders had full liberty, as I did
not consider that they had the requisite knowledge and
experience necessary for their safety; and hence, none of my
aeroplanes were launched so arranged that the rider could make
adjustments necessary for a full flight.

'This line of action caused a good deal of trouble with
aeronauts or riders, who had unbounded confidence and wanted to
make long flights after the first few trials; but I found it
necessary, as they seemed slow in comprehending the important
elements and were willing to take risks.  To give them the full
knowledge in these matters I was formulating plans for a large
starting station on the Mount Hamilton Range from which I could
launch an aeroplane capable of carrying two, one of my aeronauts
and myself, so I could teach him by demonstration.  But the
disasters consequent on the great earthquake completely stopped
all my work on these lines.  The flights that were given were
only the first of the series with aeroplanes patterned after the
first model.  There were no aeroplanes constructed according to
the two other models, as I had not given the full demonstration
of the workings of the first, though some remarkable and
startling work was done.  On one occasion Maloney, in trying to
make a very short turn in rapid flight, pressed very hard on the
stirrup which gives a screw-shape to the wings, and made a side
somersault.  The course of the machine was very much like one
turn of a corkscrew.  After this movement the machine continued
on its regular course.  And afterwards Wilkie, not to be outdone
by Maloney, told his friends he would do the same, and in a
subsequent flight made two side somersaults, one in one
direction and the other in an opposite, then made a deep dive
and a long glide, and, when about three hundred feet in the air,
brought the aeroplane to a sudden stop and settled to the earth. 
After these antics, I decreased the extent of the possible
change in the form of wing-surface, so as to allow only straight
sailing or only long curves in turning.

'During my work I had a few carping critics that I silenced by
this standing offer:  If they would deposit a thousand dollars I
would cover it on this proposition.  I would fasten a 150 pound
sack of sand in the rider's seat, make the necessary
adjustments, and send up an aeroplane upside down with a
balloon, the aeroplane to be liberated by a time fuse.  If the
aeroplane did not immediately right itself, make a flight, and
come safely to the ground, the money was theirs.

'Now a word in regard to the fatal accident.  The circumstances
are these:  The ascension was given to entertain a military
company in which were many of Maloney's friends, and he had told
them he would give the most sensational flight they ever heard
of.  As the balloon was rising with the aeroplane, a guy rope
dropping switched around the right wing and broke the tower that
braced the two rear wings and which also gave control over the
tail.  We shouted Maloney that the machine was broken, but he
probably did not hear us, as he was at the same time saying,
&quot;Hurrah for Montgomery's airship,&quot; and as the break was behind
him, he may not have detected it.  Now did he know of the
breakage or not, and if he knew of it did he take a risk so as
not to disappoint his friends?  At all events, when the machine
started on its flight the rear wings commenced to flap (thus
indicating they were loose), the machine turned on its back, and
settled a little faster than a parachute.  When we reached
Maloney he was unconscious and lived only thirty minutes.  The
only mark of any kind on him was a scratch from a wire on the
side of his neck.  The six attending physicians were puzzled at
the cause of his death.  This is remarkable for a vertical
descent of over 2,000 feet.'

The flights were brought to an end by the San Francisco
earthquake in April, 1906, which, Montgomery states, 'Wrought
such a disaster that I had to turn my attention to other
subjects and let the aeroplane rest for a time.'  Montgomery
resumed experiments in 1911 in California, and in October of
that year an accident brought his work to an end.  The report in
the American Aeronautics says that 'a little whirlwind caught
the machine and dashed it head on to the ground; Professor
Montgomery landed on his head and right hip.  He did not believe
himself seriously hurt, and talked with his year-old bride in
the tent.  He complained of pains in his back, and continued to
grow worse until he died.'

==IX.  NOT PROVEN==

The early history of flying, like that of most sciences, is
replete with tragedies; in addition to these it contains one
mystery concerning Clement Ader, who was well known among
European pioneers in the development of the telephone, and first
turned his attention to the problems of mechanical flight in
1872.  At the outset he favoured the ornithopter principle,
constructing a machine in the form of a bird with a wing-spread
of twenty-six feet; this, according to Ader's conception, was to
fly through the efforts of the operator.  The result of such an
attempt was past question and naturally the machine never left
the ground.

A pause of nineteen years ensued, and then in 1886 Ader turned
his mind to the development of the aeroplane, constructing a
machine of bat-like form with a wingspread of about forty-six
feet, a weight of eleven hundred pounds, and a steam-power plant
of between twenty and thirty horse-power driving a four-bladed
tractor screw.  On October 9th, 1890, the first trials of this
machine were made, and it was alleged to have flown a distance
of one hundred and sixty-four feet.  Whatever truth there may be
in the allegation, the machine was wrecked through deficient
equilibrium at the end of the trial.  Ader repeated the
construction, and on October 14th, 1897, tried out his third
machine at the military establishment at Satory in the presence
of the French military authorities, on a circular track
specially prepared for the experiment.  Ader and his friends
alleged that a flight of nearly a thousand feet was made; again
the machine was wrecked at the end of the trial, and there
Ader's practical work may be said to have ended, since no more
funds were forthcoming for the subsidy of experiments.

There is the bald narrative, but it is worthy of some
amplification.  If Ader actually did what he claimed, then the
position which the Wright Brothers hold as first to navigate the
air in a power-driven plane is nullified.  Although at this time
of writing it is not a quarter of a century since Ader's
experiment in the presence of witnesses competent to judge on
his accomplishment, there is no proof either way, and whether he
was or was not the first man to fly remains a mystery in the
story of the conquest of the air.

The full story of Ader's work reveals a persistence and
determination to solve the problem that faced him which was
equal to that of Lilienthal.  He began by penetrating into the
interior of Algeria after having disguised himself as an Arab,
and there he spent some months in studying flight as practiced
by the vultures of the district.  Returning to France in 1886 he
began to construct the 'Eole,' modelling it, not on the vulture,
but in the shape of a bat.  Like the Lilienthal and Pilcher
gliders this machine was fitted with wings which could be
folded; the first flight made, as already noted, on October 9th,
1890, took place in the grounds of the chateau d'Amainvilliers,
near Bretz; two fellow-enthusiasts named Espinosa and Vallier
stated that a flight was actually made; no statement in the
history of aeronautics has been subject of so much question, and
the claim remains unproved.

It was in September of 1891 that Ader, by permission of the
Minister of War, moved the 'Eole' to the military establishment
at Satory for the purpose of further trial.  By this time,
whether he had flown or not, his nineteen years of work in
connection with the problems attendant on mechanical flight had
attracted so much attention that henceforth his work was subject
to the approval of the military authorities, for already it was
recognised that an efficient flying machine would confer an
inestimable advantage on the power that possessed it in the
event of war.  At Satory the 'Eole' was alleged to have made a
flight of 109 yards, or, according to another account, 164 feet,
as stated above, in the trial in which the machine wrecked
itself through colliding with some carts which had been placed
near the track--the root cause of this accident, however, was
given as deficient equilibrium.

Whatever the sceptics may say, there is reason for belief in the
accomplishment of actual flight by Ader with his first machine
in the fact that, after the inevitable official delay of some
months, the French War Ministry granted funds for further
experiment.  Ader named his second machine, which he began to
build in May, 1892, the 'Avion,' and--an honour which he well
deserve--that name remains in French aeronautics as descriptive
of the power-driven aeroplane up to this day.

This second machine, however, was not a success, and it was not
until 1897 that the second 'Avion,' which was the third
power-driven aeroplane of Ader's construction, was ready for
trial.  This was fitted with two steam motors of twenty
horse-power each, driving two four-bladed propellers; the wings
warped automatically:  that is to say, if it were necessary to
raise the trailing edge of one wing on the turn, the trailing
edge of the opposite wing was also lowered by the same movement;
an under-carriage was also fitted, the machine running on three
small wheels, and levers controlled by the feet of the aviator
actuated the movement of the tail planes.

On October the 12th, 1897, the first trials of this 'Avion' were
made in the presence of General Mensier, who admitted that the
machine made several hops above the ground, but did not consider
the performance as one of actual flight.  The result was so
encouraging, in spite of the partial failure, that, two days
later, General Mensier, accompanied by General Grillon, a
certain Lieutenant Binet, and two civilians named respectively
Sarrau and Leaute, attended for the purpose of giving the
machine an official trial, over which the great controversy
regarding Ader's success or otherwise may be said to have
arisen.

We will take first Ader's own statement as set out in a very
competent account of his work published in Paris in 1910.  Here
are Ader's own words:  'After some turns of the propellers, and
after travelling a few metres, we started off at a lively pace;
the pressure-gauge registered about seven atmospheres; almost
immediately the vibrations of the rear wheel ceased; a little
later we only experienced those of the front wheels at
intervals.  'Unhappily, the wind became suddenly strong, and we
had some difficulty in keeping the &quot;Avion&quot; on the white line. 
We increased the pressure to between eight and nine atmospheres,
and  immediately the speed increased considerably, and the
vibrations of the wheels were no longer sensible; we were at
that moment at the point marked G in the sketch; the &quot;Avion&quot;
then found itself freely supported by its wings; under the
impulse of the wind it continually tended to go outside the
(prepared) area to the right, in spite of the action of the
rudder.  On reaching the point V it found itself in a very
critical position; the wind blew strongly and across the
direction of the white line which it ought to follow; the
machine then, although still going forward, drifted quickly out
of the area; we immediately put over the rudder to the left as
far as it would go; at the same time increasing the pressure
still more, in order to try to regain the course.  The &quot;Avion&quot;
obeyed, recovered a little, and remained for some seconds headed
towards its intended course, but it could not struggle against
the wind; instead of going back, on the contrary it drifted
farther and farther away.  And ill-luck had it that the drift
took the direction towards part of the School of Musketry, which
was guarded by posts and barriers.  Frightened at the prospect
of breaking ourselves against these obstacles, surprised at
seeing the earth getting farther away from under the &quot;Avion,&quot;
and very much impressed by seeing it rushing sideways at a
sickening speed, instinctively we stopped everything.  What
passed through our thoughts at this moment which threatened a
tragic turn would be difficult to set down.  All at once came a
great shock, splintering, a heavy concussion:  we had landed.'

Thus speaks the inventor; the cold official mind gives out a
different account, crediting the 'Avion' with merely a few hops,
and to-day, among those who consider the problem at all, there
is a little group which persists in asserting that to Ader
belongs the credit of the first power-driven flight, while a
larger group is equally persistent in stating that, save for a
few ineffectual hops, all three wheels of the machine never left
the ground.  It is past question that the 'Avion' was capable of
power-driven flight; whether it achieved it or no remains an
unsettled problem.

Ader's work is negative proof of the value of such experiments
as Lilienthal, Pilcher, Chanute, and Montgomery conducted; these
four set to work to master the eccentricities of the air before
attempting to use it as a supporting medium for continuous
flight under power; Ader attacked the problem from the other
end; like many other experimenters he regarded the air as a
stable fluid capable of giving such support to his machine as
still water might give to a fish, and he reckoned that he had
only to produce the machine in order to achieve flight.  The
wrecked 'Avion' and the refusal of the French War Ministry to
grant any more funds for further experiment are sufficient
evidence of the need for working along the lines taken by the
pioneers of gliding rather than on those which Ader himself
adopted.

Let it not be thought that in this comment there is any desire
to derogate from the position which Ader should occupy in any
study of the pioneers of aeronautical enterprise.  If he failed,
he failed magnificently, and if he succeeded, then the student
of aeronautics does him an injustice and confers on the Brothers
Wright an honour which, in spite of the value of their work,
they do not deserve.  There was one earlier than Ader, Alphonse
Penaud, who, in the face of a lesser disappointment than that
which Ader must have felt in gazing on the wreckage of his
machine, committed suicide; Ader himself, rendered unable to do
more, remained content with his achievement, and with the
knowledge that he had played a good part in the long search
which must eventually end in triumph.  Whatever the world might
say, he himself was certain that he had achieved flight.  This,
for him, was perforce enough.

Before turning to consideration of the work accomplished by the
Brothers Wright, and their proved conquest of the air, it is
necessary first to sketch as briefly as may be the experimental
work of Sir (then Mr) Hiram Maxim, who, in his book, Artificial
and Natural Flight, has given a fairly complete account of his
various experiments.  He began by experimenting with models,
with screw-propelled planes so attached to a horizontal movable
arm that when the screw was set in motion the plane described a
circle round a central point, and, eventually, he built a giant
aeroplane having a total supporting area of 1,500 square feet,
and a wing-span of fifty feet.  It has been thought advisable to
give a fairly full description of the power plant used to the
propulsion of this machine in the section devoted to engine
development.  The aeroplane, as Maxim describes it, had five
long and narrow planes projecting from each side, and a main or
central plane of pterygoid aspect.  A fore and aft rudder was
provided, and had all the auxiliary planes been put in position
for experimental work a total lifting surface of 6,000 square
feet could have been obtained.  Maxim, however, did not use more
than 4,000 square feet of lifting surface even in his later
experiments; with this he judged the machine capable of lifting
slightly under 8,000 lbs. weight, made up of 600 lbs. water in
the boiler and tank, a crew of three men, a supply of naphtha
fuel, and the weight of the machine itself.

Maxim's intention was, before attempting free flight, to get as
much data as possible regarding the conditions under which
flight must be obtained, by what is known in these days as
'taxi-ing'--that is, running the propellers at sufficient speed
to drive the machine along the ground without actually mounting
into the air.  He knew that he had an immense lifting surface
and a tremendous amount of power in his engine even when the
total weight of the experimental plant was taken into
consideration, and thus he set about to devise some means of
keeping the machine on the nine foot gauge rail track which had
been constructed for the trials.  At the outset he had a set of
very heavy cast-iron wheels made on which to mount the machine,
the total weight of wheels, axles, and connections being about
one and a half tons.  These were so constructed that the light
flanged wheels which supported the machine on the steel rails
could be lifted six inches above the track, still leaving the
heavy wheels on the rails for guidance of the machine.  'This
arrangement,' Maxim states, 'was tried on several occasions, the
machine being run fast enough to lift the forward end off the
track.  However, I found considerable difficulty in starting and
stopping quickly on account of the great weight, and the amount
of energy necessary to set such heavy wheels spinning at a high
velocity.  The last experiment with these wheels was made when a
head wind was blowing at the rate of about ten miles an hour. 
It was rather unsteady, and when the machine was running at its
greatest velocity, a sudden gust lifted not only the front end,
but also the heavy front wheels completely off the track, and
the machine falling on soft ground was soon blown over by the
wind.'

Consequently, a safety track was provided, consisting of squared
pine logs, three inches by nine inches, placed about two feet
above the steel way and having a thirty-foot gauge.  Four extra
wheels were fitted to the machine on outriggers and so adjusted
that, if the machine should lift one inch clear of the steel
rails, the wheels at the ends of the outriggers would engage the
under side of the pine trackway.

The first fully loaded run was made in a dead calm with 150 lbs. 
steam pressure to the square inch, and there was no sign of the
wheels leaving the steel track.  On a second run, with 230 lbs. 
steam pressure the machine seemed to alternate between adherence
to the lower and upper tracks, as many as three of the outrigger
wheels engaging at the same time, and the weight on the steel
rails being reduced practically to nothing.  In preparation for
a third run, in which it was intended to use full power, a
dynamometer was attached to the machine and the engines were
started at 200 lbs. pressure, which was gradually increased to
310 lbs per square inch.  The incline of the track, added to the
reading of the dynamometer, showed a total screw thrust of 2,164
lbs.  After the dynamometer test had been completed, and
everything had been made ready for trial in motion, careful
observers were stationed on each side of the track, and the
order was given to release the machine.  What follows is best
told in Maxim's own words:--

'The enormous screw-thrust started the engine so quickly that it
nearly threw the engineers off their feet, and the machine
bounded over the track at a great rate. Upon noticing a slight
diminution in the steam pressure, I turned on more gas, when
almost instantly the steam commenced to blow a steady blast from
the small safety valve, showing that the pressure was at least
320 lbs. in the pipes supplying the engines with steam.  Before
starting on this run, the wheels that were to engage the upper
track were painted, and it was the duty of one of my assistants
to observe these wheels during the run, while another assistant
watched the pressure gauges and dynagraphs. The first part of
the track was up a slight incline, but the machine was lifted
clear of the lower rails and all of the top wheels were fully
engaged on the upper track when about 600 feet had been covered. 
The speed rapidly increased, and when 900 feet had been covered,
one of the rear axle trees, which were of two-inch steel tubing,
doubled up and set the rear end of the machine completely free. 
The pencils ran completely across the cylinders of the
dynagraphs and caught on the underneath end.  The rear end of
the machine being set free, raised considerably above the track
and swayed.  At about 1,000 feet, the left forward wheel also
got clear of the upper track, and shortly afterwards the right
forward wheel tore up about 100 feet of the upper track. Steam
was at once shut off and the machine sank directly to the earth,
embedding the wheels in the soft turf without leaving any other
marks, showing most conclusively that the machine was completely
suspended in the air before it settled to the earth.  In this
accident, one of the pine timbers forming the upper track went
completely through the lower framework of the machine and broke
a number of the tubes, but no damage was done to the machinery
except a slight injury to one of the screws.'

It is a pity that the multifarious directions in which Maxim
turned his energies did not include further development of the
aeroplane, for it seems fairly certain that he was as near
solution of the problem as Ader himself, and, but for the
holding-down outer track, which was really the cause of his
accident, his machine would certainly have achieved free flight,
though whether it would have risen, flown and alighted, without
accident, is matter for conjecture.

The difference between experiments with models and with
full-sized machines is emphasised by Maxim's statement to the
effect that with a small apparatus for ascertaining the power
required for artificial flight, an angle of incidence of one in
fourteen was most advantageous, while with a large machine he
found it best to increase his angle to one in eight in order to
get the maximum lifting effect on a short run at a moderate
speed.  He computed the total lifting effect in the experiments
which led to the accident as not less than 10,000 lbs., in which
is proof that only his rail system prevented free flight.



==X. SAMUEL PIERPOINT LANGLEY==

Langley was an old man when he began the study of aeronautics,
or, as he himself might have expressed it, the study of
aerodromics, since he persisted in calling the series of
machines he built 'Aerodromes,' a word now used only to denote
areas devoted to use as landing spaces for flying machines; the
Wright Brothers, on the other hand, had the great gift of youth
to aid them in their work.  Even so it was a great race between
Langley, aided by Charles Manly, and Wilbur and Orville Wright,
and only the persistent ill-luck which dogged Langley from the
start to the finish of his experiments gave victory to his
rivals.  It has been proved conclusively in these later years of
accomplished flight that the machine which Langley launched on
the Potomac River in October of 1903 was fully capable of
sustained flight, and only the accidents incurred in launching
prevented its pilot from being the first man to navigate the air
successfully in a power-driven machine.

The best account of Langley's work is that diffused throughout a
weighty tome issued by the Smithsonian Institution, entitled the
Langley Memoir on Mechanical Flight, of which about one-third
was written by Langley himself, the remainder being compiled by
Charles M. Manly, the engineer responsible for the construction
of the first radial aero-engine, and chief assistant to Langley
in his experiments.  To give a twentieth of the contents of this
volume in the present short account of the development of
mechanical flight would far exceed the amount of space that can
be devoted even to so eminent a man in aeronautics as S. P.
Langley, who, apart from his achievement in the construction of
a power-driven aeroplane really capable of flight, was a
scientist of no mean order, and who brought to the study of
aeronautics the skill of the trained investigator allied to the
inventive resource of the genius.

That genius exemplified the antique saw regarding the infinite
capacity for taking pains, for the Langley Memoir shows that as
early as 1891 Langley had completed a set of experiments,
lasting through years, which proved it possible to construct
machines giving such a velocity to inclined surfaces that bodies
indefinitely heavier than air could be sustained upon it and
propelled through it at high speed.  For full account (very
full) of these experiments, and of a later series leading up to
the construction of a series of 'model aerodromes' capable of
flight under power, it is necessary to turn to the bulky memoir
of Smithsonian origin.

The account of these experiments as given by Langley himself
reveals the humility of the true investigator. Concerning them,
Langley remarks that, 'Everything here has been done with a view
to putting a trial aerodrome successfully in flight within a few
years, and thus giving an early demonstration of the only kind
which is conclusive in the eyes of the scientific man, as well
as of the general public--a demonstration that mechanical flight
is possible--by actually flying.  All that has been done has
been with an eye principally to this immediate result, and all
the experiments given in this book are to be considered only as
approximations to exact truth.  All were made with a view, not
to some remote future, but to an arrival within the compass of a
few years at some result in actual flight that could not be
gainsaid or mistaken.'

With a series of over thirty rubber-driven models Langley
demonstrated the practicability of opposing curved surfaces to
the resistance of the air in such a way as to achieve flight, in
the early nineties of last century; he then set about finding
the motive power which should permit of the construction of
larger machines, up to man-carrying size.  The internal
combustion engine was then an unknown quantity, and he had to
turn to steam, finally, as the propulsive energy for his power
plant.  The chief problem which faced him was that of the
relative weight and power of his engine; he harked back to the
Stringfellow engine of 1868, which in 1889 came into the
possession of the Smithsonian Institution as a historical
curiosity.  Rightly or wrongly Langley concluded on examination
that this engine never had developed and never could develop
more than a tenth of the power attributed to it; consequently he
abandoned the idea of copying the Stringfellow design and set
about making his own engine.

How he overcame the various difficulties that faced him and
constructed a steam-engine capable of the task allotted to it
forms a story in itself, too long for recital here.  His first
power-driven aerodrome of model size was begun in November of
1891, the scale of construction being decided with the idea that
it should be large enough to carry an automatic steering
apparatus which would render the machine capable of maintaining
a long and steady flight.  The actual weight of the first model
far exceeded the theoretical estimate, and Langley found that a
constant increase of weight under the exigencies of construction
was a feature which could never be altogether eliminated.  The
machine was made principally of steel, the sustaining surfaces
being composed of silk stretched from a steel tube with wooden
attachments.  The first engines were the oscillating type, but
were found deficient in power.  This led to the construction of
single-acting inverted oscillating engines with high and low
pressure cylinders, and with admission and exhaust ports to
avoid the complication and weight of eccentric and valves. 
Boiler and furnace had to be specially designed; an analysis of
sustaining surfaces and the settlement of equilibrium while in
flight had to be overcome, and then it was possible to set about
the construction of the series of model aerodromes and make test
of their 'lift.'

By the time Langley had advanced sufficiently far to consider it
possible to conduct experiments in the open air, even with these
models, he had got to his fifth aerodrome, and to the year 1894. 
Certain tests resulted in failure, which in turn resulted in
further modifications of design, mainly of the engines.  By
February of 1895 Langley reported that under favourable
conditions a lift of nearly sixty per cent of the flying weight
was secured, but although this was much more than was required
for flight, it was decided to postpone trials until two machines
were ready for the test.  May, 1896, came before actual trials
were made, when one machine proved successful and another, a
later design, failed.  The difficulty with these models was that
of securing a correct angle for launching; Langley records how,
on launching one machine, it rose so rapidly that it attained an
angle of sixty degrees and then did a tail slide into the water
with its engines working at full speed, after advancing nearly
forty feet and remaining in the air for about three seconds. 
Here, Langley found that he had to obtain greater rigidity in
his wings, owing to the distortion of the form of wing under
pressure, and how he overcame this difficulty constitutes yet
another story too long for the telling here.

Field trials were first attempted in 1893, and Langley blamed
his launching apparatus for their total failure. There was a
brief, but at the same time practical, success in model flight
in 1894, extending to between six and seven seconds, but this
only proved the need for strengthening of the wing.  In 1895
there was practically no advance toward the solution of the
problem, but the flights of May 6th and November 28th, 1896,
were notably successful.  A diagram given in Langley's memoir
shows the track covered by the aerodrome on these two flights;
in the first of them the machine made three complete circles,
covering a distance of 3,200 feet; in the second, that of
November 28th, the distance covered was 4,200 feet, or about
three-quarters of a mile, at a speed of about thirty miles an
hour.

These achievements meant a good deal; they proved mechanically
propelled flight possible.  The difference between them and such
experiments as were conducted by Clement Ader, Maxim, and
others, lay principally in the fact that these latter either did
or did not succeed in rising into the air once, and then, either
willingly or by compulsion, gave up the quest, while Langley
repeated his experiments and thus attained to actual proof of
the possibilities of flight.  Like these others, however, he
decided in 1896 that he would not undertake the construction of
a large man-carrying machine.  In addition to a multitude of
actual duties, which left him practically no time available for
original research, he had as an adverse factor fully ten years
of disheartening difficulties in connection with his model
machines.  It was President McKinley who, by requesting Langley
to undertake the construction and test of a machine which might
finally lead to the development of a flying machine capable of
being used in warfare, egged him on to his final experiment. 
Langley's acceptance of the offer to construct such a machine is
contained in a letter addressed from the Smithsonian Institution
on December 12th, 1898, to the Board of Ordnance and
Fortification of the United States War Department; this letter
is of such interest as to render it worthy of reproduction:--

'Gentlemen,--In response to your invitation I repeat what I had
the honour to say to the Board--that I am willing, with the
consent of the Regents of this Institution, to undertake for the
Government the further investigation of the subject of the
construction of a flying machine on a scale capable of carrying
a man, the investigation to include the construction,
development and test of such a machine under conditions left as
far as practicable in my discretion, it being understood that my
services are given to the Government in such time as may not be
occupied by the business of the Institution, and without charge.

'I have reason to believe that the cost of the construction will
come within the sum of $50,000.00, and that not more than
one-half of that will be called for in the coming year.

'I entirely agree with what I understand to be the wish of the
Board that privacy be observed with regard to the work, and only
when it reaches a successful completion shall I wish to make
public the fact of its success.

'I attach to this a memorandum of my understanding of some
points of detail in order to be sure that it is also the
understanding of the Board, and I am, gentlemen, with much
respect, your obedient servant, S. P. Langley.'

One of the chief problems in connection with the construction of
a full-sized apparatus was that of the construction of an
engine, for it was realised from the first that a steam power
plant for a full-sized machine could only be constructed in such
a way as to make it a constant menace to the machine which it
was to propel. By this time (1898) the internal combustion
engine had so far advanced as to convince Langley that it formed
the best power plant available.  A contract was made for the
delivery of a twelve horse-power engine to weigh not more than a
hundred pounds, but this contract was never completed, and it
fell to Charles M. Manly to design the five-cylinder radial
engine, of which a brief account is included in the section of
this work devoted to aero engines, as the power plant for the
Langley machine.

The history of the years 1899 to 1903 in the Langley series of
experiments contains a multitude of detail far beyond the scope
of this present study, and of interest mainly to the designer. 
There were frames, engines, and propellers, to be considered,
worked out, and constructed.  We are concerned here mainly with
the completed machine and its trials.  Of these latter it must
be remarked that the only two actual field trials which took
place resulted in accidents due to the failure of the launching
apparatus, and not due to any inherent defect in the machine. 
It was intended that these two trials should be the first of a
series, but the unfortunate accidents, and the fact that no
further funds were forthcoming for continuance of experiments,
prevented Langley's success, which, had he been free to go
through as he intended with his work, would have been certain.

The best brief description of the Langley aerodrome in its final
form, and of the two attempted trials, is contained in the
official report of Major M. M. Macomb of the United States
Artillery Corps, which report is here given in full:--

REPORT

Experiments with working models which were concluded August 8
last having proved the principles and calculations on which the
design of the Langley aerodrome was based to be correct, the
next step was to apply these principles to the construction of a
machine of sufficient size and power to permit the carrying of a
man, who could control the motive power and guide its flight,
thus pointing the way to attaining the final goal of producing a
machine capable of such extensive and precise aerial flight,
under normal atmospheric conditions, as to prove of military or
commercial utility.

Mr C. M. Manly, working under Professor Langley, had, by the
summer of 1903, succeeded in completing an engine-driven machine
which under favourable atmospheric conditions was expected to
carry a man for any time up to half an hour, and to be capable
of having its flight directed and controlled by him.

The supporting surface of the wings was ample, and experiment
showed the engine capable of supplying more than the necessary
motive power.

Owing to the necessity of lightness, the weight of the various
elements had to be kept at a minimum, and the factor of safety
in construction was therefore exceedingly small, so that the
machine as a whole was delicate and frail and incapable of
sustaining any unusual strain.  This defect was to be corrected
in later models by utilising data gathered in future experiments
under varied conditions.

One of the most remarkable results attained was the production
of a gasoline engine furnishing over fifty continuous
horse-power for a weight of 120 lbs.

The aerodrome, as completed and prepared for test, is briefly
described by Professor Langley as 'built of steel, weighing
complete about 730 lbs., supported by 1,040 feet of sustaining
surface, having two propellers driven by a gas engine developing
continuously over fifty brake horse-power.'

The appearance of the machine prepared for flight was
exceedingly light and graceful, giving an impression to all
observers of being capable of successful flight.

On October 7 last everything was in readiness, and I witnessed
the attempted trial on that day at Widewater, Va.  On the
Potomac.  The engine worked well and the machine was launched at
about 12.15 p.m.  The trial was unsuccessful because the front
guy-post caught in its support on the launching car and was not
released in time to give free flight, as was intended, but, on
the contrary, caused the front of the machine to be dragged
downward, bending the guy-post and making the machine plunge
into the water about fifty yards in front of the house-boat. 
The machine was subsequently recovered and brought back to the
house-boat.  The engine was uninjured and the frame only slightly
damaged, but the four wings and rudder were practically destroyed
by the first plunge and subsequent towing back to the house-boat.

This accident necessitated the removal of the house-boat to
Washington for the more convenient repair of damages.

On December 8 last, between 4 and 5 p.m., another attempt at a
trial was made, this time at the junction of the Anacostia with
the Potomac, just below Washington Barracks.

On this occasion General Randolph and myself represented the
Board of Ordnance and Fortification.  The launching car was
released at 4.45 p.m. being pointed up the Anacostia towards the
Navy Yard.  My position was on the tug Bartholdi, about 150 feet
from and at right angles to the direction of proposed flight. 
The car was set in motion and the propellers revolved rapidly,
the engine working perfectly, but there was something wrong with
the launching.  The rear guy-post seemed to drag, bringing the
rudder down on the launching ways, and a crashing, rending
sound, followed by the collapse of the rear wings, showed that
the machine had been wrecked in the launching, just how, it was
impossible for me to see.  The fact remains that the rear wings
and rudder were wrecked before the machine was free of the ways. 
Their collapse deprived the machine of its support in the rear,
and it consequently reared up in front under the action of the
motor, assumed a vertical position, and then toppled over to the
rear, falling into the water a few feet in front of the boat.

Mr Manly was pulled out of the wreck uninjured and the wrecked
machine--was subsequently placed upon the house-boat, and the
whole brought back to Washington.

From what has been said it will be seen that these unfortunate
accidents have prevented any test of the apparatus in free
flight, and the claim that an engine-driven, man-carrying
aerodrome has been constructed lacks the proof which actual
flight alone can give.

Having reached the present stage of advancement in its
development, it would seem highly desirable, before laying down
the investigation, to obtain conclusive proof of the possibility
of free flight, not only because there are excellent reasons to
hope for success, but because it marks the end of a definite
step toward the attainment of the final goal.

Just what further procedure is necessary to secure successful
flight with the large aerodrome has not yet been decided upon. 
Professor Langley is understood to have this subject under
advisement, and will doubtless inform the Board of his final
conclusions as soon as practicable.

In the meantime, to avoid any possible misunderstanding, it
should be stated that even after a successful test of the
present great aerodrome, designed to carry a man, we are still
far from the ultimate goal, and it would seem as if years of
constant work and study by experts, together with the
expenditure of thousands of dollars, would still be necessary
before we can hope to produce an apparatus of practical utility
on these lines.--Washington, January 6, 1904.

A subsequent report of the Board of ordnance and Fortification
to the Secretary of War embodied the principal points in Major
Macomb's report, but as early as March 3rd, 1904, the Board came
to a similar conclusion to that of the French Ministry of War in
respect of Clement Ader's work, stating that it was not
'prepared to make an additional allotment at this time for
continuing the work.'  This decision was in no small measure due
to hostile newspaper criticisms.  Langley, in a letter to the
press explaining his attitude, stated that he did not wish to
make public the results of his work till these were certain, in
consequence of which he refused admittance to newspaper
representatives, and this attitude produced a hostility which
had effect on the United States Congress.  An offer was made to
commercialise the invention, but Langley steadfastly refused it. 
Concerning this, Manly remarks that Langley had 'given his time
and his best labours to the world without hope of remuneration,
and he could not bring himself, at his stage of life, to consent
to capitalise his scientific work.'

The final trial of the Langley aerodrome was made on December
8th, 1903; nine days later, on December 17th, the Wright
Brothers made their first flight in a power-propelled machine,
and the conquest of the air was thus achieved.  But for the two
accidents that spoilt his trials, the honour which fell to the
Wright Brothers would, beyond doubt, have been secured by Samuel
Pierpoint Langley.



==XI.  THE WRIGHT BROTHERS==

Such information as is given here concerning the Wright Brothers
is derived from the two best sources available, namely, the
writings of Wilbur Wright himself, and a lecture given by Dr
Griffith Brewer to members of the Royal Aeronautical Society. 
There is no doubt that so far as actual work in connection with
aviation accomplished by the two brothers is concerned, Wilbur
Wright's own statements are the clearest and best available. 
Apparently Wilbur was, from the beginning, the historian of the
pair, though he himself would have been the last to attempt to
detract in any way from the fame that his brother's work also
deserves.  Throughout all their experiments the two were
inseparable, and their work is one indivisible whole; in fact,
in every department of that work, it is impossible to say where
Orville leaves off and where Wilbur begins.

It is a great story, this of the Wright Brothers, and one worth
all the detail that can be spared it.  It begins on the 16th
April, 1867, when Wilbur Wright was born within eight miles of
Newcastle, Indiana.  Before Orville's birth on the 19th August,
1871, the Wright family had moved to Dayton, Ohio, and settled
on what is known as the 'West Side' of the town.  Here the
brothers grew up, and, when Orville was still a boy in his
teens, he started a printing business, which, as  Griffith
Brewer remarks, was only limited by the smallness of his machine
and small quantity of type at his disposal.  This machine was in
such a state that pieces of string and wood were incorporated in
it by way of repair, but on it Orville managed to print a boys'
paper which gained considerable popularity in Dayton 'West
Side.'  Later, at the age of seventeen, he obtained a more
efficient outfit, with which he launched a weekly newspaper,
four pages in size, entitled The West Side News.  After three
months' running the paper was increased in size and Wilbur came
into the enterprise as editor, Orville remaining publisher.  In
1894 the two brothers began the publication of a weekly
magazine, Snap-Shots, to which Wilbur contributed a series of
articles on local affairs that gave evidence of the incisive and
often sarcastic manner in which he was able to express himself
throughout his life.  Dr Griffith Brewer describes him as a
fearless critic, who wrote on matters of local interest in a
kindly but vigorous manner, which did much to maintain the
healthy public municipal life of Dayton.

Editorial and publishing enterprise was succeeded by the
formation, just across the road from the printing works, of the
Wright Cycle Company, where the two brothers launched out as
cycle manufacturers with the 'Van Cleve' bicycle, a machine of
great local repute for excellence of construction, and one which
won for itself a reputation that lasted long after it had ceased
to be manufactured.  The name of the machine was that of an
ancestor of the brothers, Catherine Van Cleve, who was one of
the first settlers at Dayton, landing there from the River Miami
on April 1st, 1796, when the country was virgin forest. 

It was not until 1896 that the mechanical genius which
characterised the two brothers was turned to the consideration
of aeronautics.  In that year they took up the problem
thoroughly, studying all the aeronautical information then in
print.  Lilienthal's writings formed one basis for their
studies, and the work of Langley assisted in establishing in
them a confidence in the possibility of a solution to the
problems of mechanical flight.  In 1909, at the banquet given by
the Royal Aero Club to the Wright Brothers on their return to
America, after the series of demonstration flights carried out
by Wilbur Wright on the Continent, Wilbur paid tribute to the
great pioneer work of Stringfellow, whose studies and
achievements influenced his own and Orville's early work.  He
pointed out how Stringfellow devised an aeroplane having two
propellers and vertical and horizontal steering, and gave due
place to this early pioneer of mechanical flight.

Neither of the brothers was content with mere study of the work
of others.  They collected all the theory available in the books
published up to that time, and then built man-carrying gliders
with which to test the data of Lilienthal and such other
authorities as they had consulted.  For two years they conducted
outdoor experiments in order to test the truth or otherwise of
what were enunciated as the principles of flight; after this
they turned to laboratory experiments, constructing a wind
tunnel in which they made thousands of tests with models of
various forms of curved planes.  From their experiments they
tabulated thousands of readings, which Griffith Brewer remarks
as giving results equally efficient with those of the elaborate
tables prepared by learned institutions. 

Wilbur Wright has set down the beginnings of the practical
experiments made by the two brothers very clearly.  'The
difficulties,' he says, 'which obstruct the pathway to success
in flying machine construction are of three general classes: 
(1) Those which relate to the construction of the sustaining
wings; (2) those which relate to the generation and application
of the power required to drive the machine through the air; (3)
those relating to the balancing and steering of the machine
after it is actually in flight.  Of these difficulties two are
already to a certain extent solved.  Men already know how to
construct wings, or aeroplanes, which, when driven through the
air at sufficient speed, will not only sustain the weight of the
wings themselves, but also that of the engine and the engineer
as well.  Men also know how to build engines and' screws of
sufficient lightness and power to drive these planes at
sustaining speed.  Inability to balance and steer still
confronts students of the flying problem, although nearly ten
years have passed (since Lilienthal's success).  When this one
feature has been worked out, the age of flying machines will
have arrived, for all other difficulties are of minor
importance.

'The person who merely watches the flight of a bird gathers the
impression that the bird has nothing to think of but the
flapping of its wings.  As a matter of fact, this is a very
small part of its mental labour.  Even to mention all the things
the bird must constantly keep in mind in order to fly securely
through the air would take a considerable time.  If I take a
piece of paper and, after placing it parallel with the ground,
quickly let it fall, it will not settle steadily down as a
staid, sensible piece of paper ought to do, but it insists on
contravening every recognised rule of decorum, turning over and
darting hither and thither in the most erratic manner, much
after the style of an untrained horse. Yet this is the style of
steed that men must learn to manage before flying can become an
everyday sport.  The bird has learned this art of equilibrium,
and learned it so thoroughly that its skill is not apparent to
our sight.  We only learn to appreciate it when we can imitate
it.

'Now, there are only two ways of learning to ride a fractious
horse:  one is to get on him and learn by actual practice how
each motion and trick may be best met; the other is to sit on a
fence and watch the beast awhile, and then retire to the house
and at leisure figure out the best way of overcoming his jumps
and kicks.  The latter system is the safer, but the former, on
the whole, turns out the larger proportion of good riders.  It
is very much the same in learning to ride a flying machine; if
you are looking for perfect safety you will do well to sit on a
fence and watch the birds, but if you really wish to learn you
must mount a machine and become acquainted with its tricks by
actual trial.  The balancing of a gliding or flying machine is
very simple in theory.  It merely consists in causing the centre
of pressure to coincide with the centre of gravity.'

These comments are taken from a lecture delivered by Wilbur
Wright before the Western Society of Engineers in September of
1901, under the presidency of Octave Chanute.  In that lecture
Wilbur detailed the way in which he and his brother came to
interest themselves in aeronautical problems and constructed
their first glider. He speaks of his own notice of the death of
Lilienthal in 1896, and of the way in which this fatality roused
him to an active interest in aeronautical problems, which was
stimulated by reading Professor Marey's Animal Mechanism, not
for the first time.  'From this I was led to read more modern
works, and as my brother soon became equally interested with
myself, we soon passed from the reading to the thinking, and
finally to the working stage.  It seemed to us that the main
reason why the problem had remained so long unsolved was that no
one had been able to obtain any adequate practice.  We figured
that Lilienthal in five years of time had spent only about five
hours in actual gliding through the air.  The wonder was not
that he had done so little, but that he had accomplished so
much.  It would not be considered at all safe for a bicycle
rider to attempt to ride through a crowded city street after
only five hours' practice, spread out in bits of ten seconds
each over a period of five years; yet Lilienthal with this brief
practice was remarkably successful in meeting the fluctuations
and eddies of wind-gusts.  We thought that if some method could
be found by which it would be possible to practice by the hour
instead of by the second there would be hope of advancing the
solution of a very difficult problem.  It seemed feasible to do
this by building a machine which would be sustained at a speed
of eighteen miles per hour, and then finding a locality where
winds of this velocity were common.  With these conditions a
rope attached to the machine to keep it from floating backward
would answer very nearly the same purpose as a propeller driven
by a motor, and it would be possible to practice by the hour,
and without any serious danger, as it would not be necessary to
rise far from the ground, and the machine would not have any
forward motion at all.  We found, according to the accepted
tables of air pressure on curved surfaces, that a machine
spreading 200 square feet of wing surface would be sufficient
for our purpose, and that places would easily be found along the
Atlantic coast where winds of sixteen to twenty-five miles were
not at all uncommon.  When the winds were low it was our plan to
glide from the tops of sandhills, and when they were
sufficiently strong to use a rope for our motor and fly over one
spot.  Our next work was to draw up the plans for a suitable
machine.  After much study we finally concluded that tails were
a source of trouble rather than of assistance, and therefore we
decided to dispense with them altogether.  It seemed reasonable
that if the body of the operator could be placed in a horizontal
position instead of the upright, as in the machines of
Lilienthal, Pilcher, and Chanute, the wind resistance could be
very materially reduced, since only one square foot instead of
five would be exposed.  As a full half horse-power would be
saved by this change, we arranged to try at least the horizontal
position.  Then the method of control used by Lilienthal, which
consisted in shifting the body, did not seem quite as quick or
effective as the case required; so, after long study, we
contrived a system consisting of two large surfaces on the
Chanute double-deck plan, and a smaller surface placed a short
distance in front of the main surfaces in such a position that
the action of the wind upon it would counterbalance the effect
of the travel of the centre of pressure on the main surfaces. 
Thus changes in the direction and velocity of the wind would
have little disturbing effect, and the operator would be
required to attend only to the steering of the machine, which
was to be effected by curving the forward surface up or down. 
The lateral equilibrium and the steering to right or left was to
be attained by a peculiar torsion of the main surfaces which was
equivalent to presenting one end of the wings at a greater angle
than the other.  In the main frame a few changes were also made
in the details of construction and trussing employed by Mr
Chanute.  The most important of these were:  (1) The moving of
the forward main crosspiece of the frame to the extreme front
edge; (2) the encasing in the cloth of all crosspieces and ribs
of the surfaces; (3) a rearrangement of the wires used in
trussing the two surfaces together, which rendered it possible
to tighten all the wires by simply shortening two of them.'

The brothers intended originally to get 200 square feet of
supporting surface for their glider, but the impossibility of
obtaining suitable material compelled them to reduce the area to
165 square feet, which, by the Lilienthal tables, admitted of
support in a wind of about twenty-one miles an hour at an angle
of three degrees.  With this glider they went in the summer of I 
1900 to the little settlement of Kitty Hawk, North Carolina,
situated on the strip of land dividing Albemarle Sound from the
Atlantic.  Here they reckoned on obtaining steady wind, and
here, on the day that they completed the machine, they took it
out for trial as a kite with the wind blowing at between
twenty-five and thirty miles an hour.  They found that in order
to support a man on it the glider required an angle nearer
twenty degrees than three, and even with the wind at thirty
miles an hour they could not get down to the planned angle of
three degrees.  'Later, when the wind was too light to support
the machine with a man on it,  they tested it as a kite, working
the rudders by cords. Although they obtained satisfactory
results in this way they realised fully that actual gliding
experience was necessary before the tests could be considered
practical.

A series of actual measurements of lift and drift of the machine
gave astonishing results.  'It appeared that the total
horizontal pull of the machine, while sustaining a weight of 52
lbs., was only 8.5 lbs., which was less than had been previously
estimated for head resistance of the framing alone.  Making
allowance for the weight carried, it appeared that the head
resistance of the framing was but little more than fifty per
cent of the amount which Mr Chanute had estimated as the head
resistance of the framing of his machine.  On the other hand, it
appeared sadly deficient in lifting power as compared with the
calculated lift of curved surfaces of its size... we decided to
arrange our machine for the following year so that the depth of
curvature of its surfaces could be varied at will, and its
covering air-proofed.'

After these experiments the brothers decided to turn to
practical gliding, for which they moved four miles to the south,
to the Kill Devil sandhills, the principal of which is slightly
over a hundred feet in height, with an inclination of nearly ten
degrees on its main north-western slope.  On the day after their
arrival they made about a dozen glides, in which, although the
landings were made at a speed of more than twenty miles an hour,
no injury was sustained either by the machine or by the
operator.

'The slope of the hill was 9.5 degrees, or a drop of one foot in
six.  We found that after attaining a speed of about twenty-five
to thirty miles with reference to the wind, or ten to fifteen
miles over the ground, the machine not only glided parallel to
the slope of the hill, but greatly increased its speed, thus
indicating its ability to glide on a somewhat less angle than
9.5 degrees, when we should feel it safe to rise higher from the
surface.  The control of the machine proved even better than we
had dared to expect, responding quickly to the slightest motion
of the rudder.  With these glides our experiments for the year
1900 closed.  Although the hours and hours of practice we had
hoped to obtain finally dwindled down to about two minutes, we
were very much pleased with the general results of the trip,
for, setting out as we did with almost revolutionary theories on
many points and an entirely untried form of machine, we
considered it quite a point to be able to return without having
our pet theories completely knocked on the head by the hard
logic of experience, and our own brains dashed out in the
bargain. Everything seemed to us to confirm the correctness of
our original opinions:  (1) That practice is the key to the
secret of flying; (2) that it is practicable to assume the
horizontal position; (3) that a smaller surface set at a
negative angle in front of the main bearing surfaces, or wings,
will largely counteract the effect of the fore and aft travel of
the centre of pressure; (4) that steering up and down can be
attained with a rudder without moving the position of the
operator's body; (5) that twisting the wings so as to present
their ends to the wind at different angles is a more prompt and
efficient way of maintaining lateral equilibrium than shifting
the body of the operator.'

For the gliding experiments of 1901 it was decided to retain the
form of the 1900 glider, but to increase the area to 308 square
feet, which, the brothers calculated, would support itself and
its operator in a wind of seventeen miles an hour with an angle
of incidence of three degrees.  Camp was formed at Kitty Hawk in
the middle of July, and on July 27th the machine was completed
and tried for the first time in a wind of about fourteen miles
an hour.  The first attempt resulted in landing after a glide of
only a few yards, indicating that the centre of gravity was too
far in front of the centre of pressure.  By shifting his
position farther and farther back the operator finally achieved
an undulating flight of a little over 300 feet, but to obtain
this success he had to use full power of the rudder to prevent
both stalling and nose-diving. With the 1900 machine one-fourth
of the rudder action had been necessary for far better control.

Practically all glides gave the same result, and in one the
machine rose higher and higher until it lost all headway.  'This
was the position from which Lilienthal had always found
difficulty in extricating himself, as his machine then, in spite
of his greatest exertions, manifested a tendency to dive
downward almost vertically and strike the ground head on with
frightful velocity.  In this case a warning cry from the ground
caused the operator to turn the rudder to its full extent and
also to move his body slightly forward.  The machine then
settled slowly to the ground, maintaining its horizontal
position almost perfectly, and landed without any injury at all. 
This was very encouraging, as it showed that one of the very
greatest dangers in machines with horizontal tails had been
overcome by the use of the front rudder.  Several glides later
the same experience was repeated with the same result.  In the
latter case the machine had even commenced to move backward, but
was nevertheless brought safely to the ground in a horizontal
position.  On the whole this day's experiments were encouraging,
for while the action of the rudder did not seem at all like that
of our 1900 machine, yet we had escaped without difficulty from
positions which had proved very dangerous to preceding
experimenters, and after less than one minute's actual practice
had made a glide of more than 300 feet, at an angle of descent
of ten degrees, and with a machine nearly twice as large as had
previously been considered safe.  The trouble with its control,
which has been mentioned, we believed could be corrected when we
should have located its cause.'

It was finally ascertained that the defect could be remedied by
trussing down the ribs of the whole machine so as to reduce the
depth of curvature.  When this had been done gliding was
resumed, and after a few trials glides of 366 and 389 feet were
made with prompt response on the part of the machine, even to
small movements of the rudder.  The rest of the story of the
gliding experiments of 1901 cannot be better told than in Wilbur
Wright's own words, as uttered by him in the lecture from which
the foregoing excerpts have been made.

'The machine, with its new curvature, never failed to respond
promptly to even small movements of the rudder. The operator
could cause it to almost skim the ground, following the
undulations of its surface, or he could cause it to sail out
almost on a level with the starting point, and, passing high
above the foot of the hill, gradually settle down to the ground. 
The wind on this day was blowing eleven to fourteen miles per
hour.  The next day, the conditions being favourable, the
machine was again taken out for trial.  This time the velocity
of the wind was eighteen to twenty-two miles per hour.  At first
we felt some doubt as to the safety of attempting free flight in
so strong a wind, with a machine of over 300 square feet and a
practice of less than five minutes spent in actual flight.  But
after several preliminary experiments we decided to try a glide. 
The control of the machine seemed so good that we then felt no
apprehension in sailing boldly forth.  And thereafter we made
glide after glide, sometimes following the ground closely and
sometimes sailing high in the air.  Mr Chanute had his camera
with him and took pictures of some of these glides, several of
which are among those shown.

'We made glides on subsequent days, whenever the conditions were
favourable.  The highest wind thus experimented in was a little
over twelve metres per second--nearly twenty-seven miles per
hour.

It had been our intention when building the machine to do the
larger part of the experimenting in the following manner:--When
the wind blew seventeen miles an hour, or more, we would attach
a rope to the machine and let it rise as a kite with the
operator upon it.  When it should reach a proper height the
operator would cast off the rope and glide down to the ground
just as from the top of a hill.  In this way we would be saved
the trouble of carrying the machine uphill after each glide, and
could make at least ten glides in the time required for one in
the other way.  But when we came to try it, we found that a wind
of seventeen miles, as measured by Richards' anemometer, instead
of sustaining the machine with its operator, a total weight of
240 lbs., at an angle of incidence of three degrees, in reality
would not sustain the machine alone--100 lbs.--at this angle. 
Its lifting capacity seemed scarcely one third of the calculated
amount.  In order to make sure that this was not due to the
porosity of the cloth, we constructed two small experimental
surfaces of equal size, one of which was air-proofed and the
other left in its natural state; but we could detect no
difference in their lifting powers.  For a time we were led to
suspect that the lift of curved surfaces very little exceeded
that of planes of the same size, but further investigation and
experiment led to the opinion that (1) the anemometer used by us
over-recorded the true velocity of the wind by nearly 15 per
cent; (2) that the well-known Smeaton co-efficient of .005 V
squared for the wind pressure at 90 degrees is probably too
great by at least 20 per cent; (3) that Lilienthal's estimate
that the pressure on a curved surface having an angle of
incidence of 3 degrees equals .545 of the pressure at go degrees
is too large, being nearly 50 per cent greater than very recent
experiments of our own with a pressure testing-machine indicate;
(4) that the superposition of the surfaces somewhat reduced the
lift per square foot, as compared with a single surface of equal
area.

'In gliding experiments, however, the amount of lift is of less
relative importance than the ratio of lift to drift, as this
alone decides the angle of gliding descent.  In a plane the
pressure is always perpendicular to the surface, and the ratio
of lift to drift is therefore the same as that of the cosine to
the sine of the angle of incidence.  But in curved surfaces a
very remarkable situation is found.  The pressure, instead of
being uniformly normal to the chord of the arc, is usually
inclined considerably in front of the perpendicular.  The result
is that the lift is greater and the drift less than if the
pressure were normal.  Lilienthal was the first to discover this
exceedingly important fact, which is fully set forth in his
book, Bird Flight the Basis of the Flying Art, but owing to some
errors in the methods he used in making measurements, question
was raised by other investigators not only as to the accuracy of
his figures, but even as to the existence of any tangential
force at all.  Our experiments confirm the existence of this
force, though our measurements differ considerably from those of
Lilienthal.  While at Kitty Hawk we spent much time in measuring
the horizontal pressure on our unloaded machine at various
angles of incidence.  We found that at 13 degrees the horizontal
pressure was about 23 lbs.  This included not only the drift
proper, or horizontal component of the pressure on the side of
the surface, but also the head resistance of the framing as
well.  The weight of the machine at the time of this test was
about 108 lbs.  Now, if the pressure had been normal to the
chord of the surface, the drift proper would have been to the
lift (108 lbs.) as the sine of 13 degrees is to the cosine of 13
degrees, or .22 X 108/.97 = 24+ lbs.; but this slightly exceeds
the total pull of 23 pounds on our scales.  Therefore it is
evident that the average pressure on the surface, instead of
being normal to the chord, was so far inclined toward the front
that all the head resistance of framing and wires used in the
construction was more than overcome.  In a wind of fourteen
miles per hour resistance is by no means a negligible factor, so
that tangential is evidently a force of considerable value.  In
a higher wind, which sustained the machine at an angle of 10
degrees the pull on the scales was 18 lbs.  With the pressure
normal to the chord the drift proper would have been 17 X 98/.98.
The travel of the centre of pressure made it necessary to put
sand on the front rudder to bring the centres of gravity and
pressure into coincidence, consequently the weight of the
machine varied from 98 lbs. to 108 lbs. in the different tests)=
17 lbs., so that, although the higher wind velocity must have
caused an increase in the head resistance, the tangential force
still came within 1 lb. of overcoming it.  After our return
from Kitty Hawk we began a series of experiments to accurately
determine the amount and direction of the pressure produced on
curved surfaces when acted upon by winds at the various angles
from zero to 90 degrees.  These experiments are not yet
concluded, but in general they support Lilienthal in the claim
that the curves give pressures more favourable in amount and
direction than planes; but we find marked differences in the
exact values, especially at angles below 10 degrees.  We were
unable to obtain direct measurements of the horizontal pressures
of the machine with the operator on board, but by comparing the
distance travelled with the vertical fall, it was easily
calculated that at a speed of 24 miles per hour the total
horizontal resistances of our machine, when bearing the
operator, amounted to 40 lbs., which is equivalent to about
2 1/3 horse-power.  It must not be supposed, however, that a
motor developing this power would be sufficient to drive a
man-bearing machine.  The extra weight of the motor would
require either a larger machine, higher speed, or a greater
angle of incidence in order to support it, and therefore more
power.  It is probable, however, that an engine of 6
horse-power, weighing 100 lbs.  would answer the purpose.  Such
an engine is entirely practicable.  Indeed, working motors of
one-half this weight per horse-power (9 lbs. per horse-power)
have been constructed by several different builders.  Increasing
the speed of our machine from 24 to 33 miles per hour reduced
the total horizontal pressure from 40 to about 35 lbs.  This was
quite an advantage in gliding, as it made it possible to sail
about 15 per cent farther with a given drop.  However, it would
be of little or no advantage in reducing the size of the motor
in a power-driven machine, because the lessened thrust would be
counterbalanced by the increased speed per minute.  Some years
ago Professor Langley called attention to the great economy of
thrust which might be obtained by using very high speeds, and
from this many were led to suppose that high speed was essential
to success in a motor-driven machine.  But the economy to which
Professor Langley called attention was in foot pounds per mile
of travel, not in foot pounds per minute.  It is the foot pounds
per minute that fixes the size of the motor.  The probability is
that the first flying machines will have a relatively low speed,
perhaps not much exceeding 20 miles per hour, but the problem of
increasing the speed will be much simpler in some respects than
that of increasing the speed of a steamboat; for, whereas in the
latter case the size of the engine must increase as the cube of
the speed, in the flying machine, until extremely high speeds
are reached, the capacity of the motor increases in less than
simple ratio; and there is even a decrease in the fuel per mile
of travel.  In other words, to double the speed of a steamship
(and the same is true of the balloon type of airship) eight
times the engine and boiler capacity would be required, and four
times the fuel consumption per mile of travel:  while a flying
machine would require engines of less than double the size, and
there would be an actual decrease in the fuel consumption per
mile of travel. But looking at the matter conversely, the great
disadvantage of the flying machine is apparent; for in the
latter no flight at all is possible unless the proportion of
horse-power to flying capacity is very high; but on the other
hand a steamship is a mechanical success if its ratio of
horse-power to tonnage is insignificant.  A flying machine that
would fly at a speed of 50 miles per hour with engines of 1,000
horse-power would not be upheld by its wings at all at a speed
of less than 25 miles an hour, and nothing less than 500
horse-power could drive it at this speed.  But a boat which
could make 40 miles an hour with engines of 1,000 horse-power
would still move 4 miles an hour even if the engines were
reduced to 1 horse-power. The problems of land and water travel
were solved in the nineteenth century, because it was possible
to begin with small achievements, and gradually work up to our
present success.  The flying problem was left over to the
twentieth century, because in this case the art must be highly
developed before any flight of any considerable duration at all
can be obtained.

'However, there is another way of flying which requires no
artificial motor, and many workers believe that success will
come first by this road.  I refer to the soaring flight, by
which the machine is permanently sustained in the air by the
same means that are employed by soaring birds.  They spread
their wings to the wind, and sail by the hour, with no
perceptible exertion beyond that required to balance and steer
themselves.  What sustains them is not definitely known, though
it is almost certain that it is a rising current of air.  But
whether it be a rising current or something else, it is as well
able to support a flying machine as a bird, if man once learns
the art of utilising it.  In gliding experiments it has long been
known that the rate of vertical descent is very much retarded,
and the duration of the flight greatly prolonged, if a strong
wind blows UP the face of the hill parallel to its surface.  Our
machine, when gliding in still air, has a rate of vertical
descent of nearly 6 feet per second, while in a wind blowing 26
miles per hour up a steep hill we made glides in which the rate
of descent was less than 2 feet per second. And during the larger
part of this time, while the machine remained exactly in the
rising current, THERE WAS NO DESCENT AT ALL, BUT EVEN A SLIGHT
RISE.   If the operator had had sufficient skill to keep himself
from passing beyond the rising current he would have been
sustained indefinitely at a higher point than that from which he
started.  The illustration shows one of these very slow glides at
a time when the machine was practically at a standstill.  The
failure to advance more rapidly caused the photographer some
trouble in aiming, as you will perceive.  In looking at this
picture you will readily understand that the excitement of
gliding experiments does not entirely cease with the breaking up
of camp.  In the photographic dark-room at home we pass moments
of as thrilling interest as any in the field, when the image
begins to appear on the plate and it is yet an open question
whether we have a picture of a flying machine or merely a patch
of open sky.  These slow glides in rising current probably hold
out greater hope of extensive practice than any other method
within man's reach, but they have the disadvantage of requiring
rather strong winds or very large supporting surfaces.  However,
when gliding operators have attained greater skill, they can with
comparative safety maintain themselves in the air for hours at a
time in this way, and thus by constant practice so increase
their knowledge and skill that they can rise into the higher air
and search out the currents which enable the soaring birds to
transport themselves to any desired point by first rising in a
circle and then sailing off at a descending angle.  This
illustration shows the machine, alone, flying in a wind of 35
miles per hour on the face of a steep hill, 100 feet high. It
will be seen that the machine not only pulls upward, but also
pulls forward in the direction from which the wind blows, thus
overcoming both gravity and the speed of the wind.  We tried the
same experiment with a man on it, but found danger that the
forward pull would become so strong, that the men holding the
ropes would be dragged from their insecure foothold on the slope
of the hill.  So this form of experimenting was discontinued
after four or five minutes' trial.

'In looking over our experiments of the past two years, with
models and full-size machines, the following points stand out
with clearness:--

'1.  That the lifting power of a large machine, held stationary
in a wind at a small distance from the earth, is much less than
the Lilienthal table and our own laboratory experiments would
lead us to expect.  When the machine is moved through the air,
as in gliding, the discrepancy seems much less marked.

'2.  That the ratio of drift to lift in well-shaped surfaces is
less at angles of incidence of 5 degrees to 12 degrees than at
an angle of 3 degrees.

'3.  That in arched surfaces the centre of pressure at 90
degrees is near the centre of the surface, but moves slowly
forward as the angle becomes less, till a critical angle varying
with the shape and depth of the curve is reached, after which it
moves rapidly toward the rear till the angle of no lift is
found.

'4.  That with similar conditions large surfaces may be
controlled with not much greater difficulty than small ones, if
the control is effected by manipulation of the surfaces
themselves, rather than by a movement of the body of the
operator.

'5.  That the head resistances of the framing can be brought to
a point much below that usually estimated as necessary.

'6.  That tails, both vertical and horizontal, may with safety
be eliminated in gliding and other flying experiments.

'7.  That a horizontal position of the operator's body may be
assumed without excessive danger, and thus the head resistance
reduced to about one-fifth that of the upright position.

'8.  That a pair of superposed, or tandem surfaces, has less
lift in proportion to drift than either surface separately, even
after making allowance for weight and head resistance of the
connections.'

Thus, to the end of the 1901 experiments, Wilbur Wright provided
a fairly full account of what was accomplished; the record shows
an amount of patient and painstaking work almost beyond
belief--it was no question of making a plane and launching it,
but a business of trial and error, investigation and tabulation
of detail, and the rejection time after time of previously
accepted theories, till the brothers must have felt the the
solid earth was no longer secure, at times.  Though it was
Wilbur who set down this and other records of the work done,
yet the actual work was so much Orville's as his brother's that
no analysis could separate any set of experiments and say that
Orville did this and Wilbur that--the two were inseparable.  On
this point Griffith Brewer remarked that 'in the arguments, if
one brother took one view, the other brother took the opposite
view as a matter of course, and the subject was thrashed to
pieces until a mutually acceptable result remained.  I have
often been asked since these pioneer days, &quot;Tell me, Brewer, who
was really the originator of those two?&quot; In reply, I used
first to say, &quot;I think it was mostly  Wilbur,&quot; and later,
when I came to know Orville better, I said, &quot;The thing could not
have been without Orville.&quot;  Now, when asked, I have to say, &quot; I
don't know,&quot; and I feel the more I think of it that it was only
the wonderful combination of these two brothers, who devoted
their lives together or this common object, that made the
discovery of the art of flying possible.'

Beyond the 1901 experiments in gliding, the record grows more
scrappy, less detailed.  It appears that once power-driven
flight had been achieved, the brothers were not so willing to
talk as before; considering the amount of work that they put in,
there could have been  little time for verbal description
of that work--as already  remarked, their tables still stand for
the designer and experimenter.  The end of the 1901 experiments
left both brothers somewhat discouraged, though they had
accomplished more than any others.  'Having set out with
absolute faith in the existing scientific data, we ere driven to
doubt one thing after another, finally, after two years of
experiment, we cast it all aside, and decided to rely entirely
on our own investigations.  Truth and error were everywhere so
in,timately mixed as to be indistinguishable.... We had taken up
aeronautics as a sport.  We reluctantly entered upon the
scientific side of it.'

Yet, driven thus to the more serious aspect of the work, they
found in the step its own reward, for the work of itself drew
them on and on, to the construction of measuring machines for
the avoidance of error, and to the making of series after series
of measurements, concerning which Wilbur wrote in 1908 (in the
Century Magazine) that 'after making preliminary measurements on
a great number of different shaped surfaces, to secure a general
understanding of the subject, we began systematic measurements
of standard surfaces, so varied in design as to bring out the
underlying causes of  differences noted in their pressures. 
Measurements were tabulated on nearly fifty of these at all
angles from zero to 45 degrees, at intervals of 2 1/2 degrees. 
Measurements were also secured showing the effects on each other
when surfaces are superposed, or when they follow one another.

'Some strange results were obtained.  One surface, with a heavy
roll at the front edge, showed the same lift for all angles from
7 1/2 to 45 degrees.  This seemed so anomalous that we were
almost ready to doubt our own measurements, when a simple test
was suggested.  A weather vane, with two planes attached to the
pointer at an angle of 80 degrees with each other, was made.
According to our table, such a vane would be in unstable
equilibrium when pointing directly into the wind, for if by
chance the wind should happen to strike one plane at 39 degrees
and the other at 41 degrees, the plane with the smaller angle
would have the greater pressure and the pointer would be turned
still farther out of the course of the wind until the two vanes
again secured equal pressures, which would be at approximately
30 and 50 degrees.  But the vane performed in this very manner. 
Further corroboration of the tables was obtained in experiments
with the new glider at Kill Devil Hill the next season.

'In September and October, 1902 nearly 1,000 gliding flights
were made, several of which covered distances of over 600 feet. 
Some, made against a wind of 36 miles an hour, gave proof of the
effectiveness of the devices for control.  With this machine, in
the autumn of 1903, we made a number of flights in which we
remained in the air for over a minute, often soaring for a
considerable time in one spot, without any descent at all. 
Little wonder that our unscientific assistant should think the
only thing needed to keep it indefinitely in the air would be a
coat of feathers to make it light! '

It was at the conclusion of these experiments of 1903 that the
brothers concluded they had obtained sufficient data from their
thousands of glides and multitude of calculations to permit of
their constructing and making trial of a power-driven machine. 
The first designs got out provided for a total weight of 600
lbs., which was to include the weight of the motor and the
pilot; but on completion it was found that there was a surplus
of power from the motor, and thus they had 150 lbs. weight to
allow for strengthening wings and other parts. 

They came up against the problem to which Riach has since
devoted so much attention, that of propeller design. 'We had
thought of getting the theory of the screw-propeller from the
marine engineers, and then, by applying our table of
air-pressures to their formulae, of designing air-propellers
suitable for our uses.  But, so far as we could learn, the
marine engineers possessed only empirical formulae, and the
exact action of the screw propeller, after a century of use, was
still very obscure.  As we were not in a position to undertake a
long series of practical experiments to discover a propeller
suitable for our machine, it seemed necessary to obtain such a
thorough understanding of the theory of its reactions as would
enable us to design them from calculation alone.  What at first
seemed a simple problem became more complex the longer we
studied it.  With the machine moving forward, the air flying
backward, the propellers turning sidewise, and nothing standing
still, it seemed impossible to find a starting point from which
to trace the various simultaneous reactions.  Contemplation of
it was confusing.  After long arguments we often found ourselves
in the ludicrous position of each having been converted to the
other's side, with no more agreement than when the discussion
began.

'It was not till several months had passed, and every phase of
the problem had been thrashed over and over, that the various
reactions began to untangle themselves.  When once a clear
understanding had been obtained there was no difficulty in
designing a suitable propeller, with proper diameter, pitch, and
area of blade, to meet the requirements of the flier.  High
efficiency in a screw-propeller is not dependent upon any
particular or peculiar shape, and there is no such thing as a
&quot;best&quot; screw.  A propeller giving a high dynamic efficiency when
used upon one machine may be almost worthless when used upon
another.  The propeller should in every case be designed to meet
the particular conditions of the machine to which it is to be
applied.  Our first propellers, built entirely from calculation,
gave in useful work 66 per cent of the power expended.  This was
about one-third more than had been secured by Maxim or Langley.'

Langley had made his last attempt with the 'aerodrome,' and his
splendid failure but a few days before the brothers made their
first attempt at power-driven aeroplane flight.  On December
17th, 1903, the machine was taken out; in addition to Wilbur and
Orville Wright, there were present five spectators:  Mr A. D.
Etheridge, of the Kil1 Devil life-saving station; Mr W. S.Dough,
Mr W. C. Brinkley, of Manteo; Mr John Ward, of Naghead, and Mr
John T. Daniels.[*] A general invitation had been given to
practically all the residents in the vicinity, but the Kill
Devil district is a cold area in December, and history had
recorded so many experiments in which machines had failed to
leave the ground that between temperature and scepticism only
these five risked a waste of their time.

[*] This list is as given by Wilbur Wright himself.

And these five were in at the greatest conquest man had made
since James Watt evolved the steam engine --perhaps even a
greater conquest than that of Watt.  Four flights in all were
made; the first lasted only twelve seconds, 'the first in the
history of the world in which a machine carrying a man had
raised itself into the air by its own power in free flight, had
sailed forward on a level course without reduction of speed, and
had finally landed without being wrecked,' said Wilbur
Wright concerning the achievement.[*] The next two flights were
slightly longer, and the fourth and last of the day was one
second short of the complete  minute; it was made into the teeth
of a 20 mile an hour wind, and the distance travelled was 852
feet.

[*] Century Magazine, September, 1908.

This bald statement of the day's doings is as Wilbur Wright
himself has given it, and there is in truth nothing more to say;
no amount of statement could add to the importance of the
achievement, and no more than the bare record is necessary.  The
faith that had inspired the long roll of pioneers, from da Vinci
onward, was justified at last.

Having made their conquest, the brothers took the machine back
to camp, and, as they thought, placed it in safety.  Talking
with the little group of spectators about the flights, they
forgot about the machine, and then a sudden gust of wind struck
it.  Seeing that it was being overturned, all made a rush toward
it to save it, and Mr Daniels, a man of large proportions, was
in some way lifted off his feet, falling between the planes. 
The machine overturned fully, and Daniels was shaken like a die
in a cup as the wind rolled the machine over and over--he came
out at the end of his experience with a series of bad bruises,
and no more, but the damage done to the machine by the accident
was sufficient to render it useless for further experiment that
season.

A new machine, stronger and heavier, was constructed by the
brothers, and in the spring of 1904 they began experiments again
at Sims Station, eight miles to the east of Dayton, their home
town.  Press representatives were invited for the first trial,
and about a dozen came--the whole gathering did not number more
than fifty people.  'When preparations had been concluded,'
Wilbur Wright wrote of this trial, 'a wind of only three or four
miles an hour was blowing--insufficient for starting on so short
a track --but since many had come a long way to see the machine
in action, an attempt was made.  To add to the other difficulty,
the engine refused to work properly.  The machine, after running
the length of the track, slid off the end without rising into
the air at all.  Several of the newspaper men returned next day
but were again disappointed.  The engine performed badly, and
after a glide of only sixty feet the machine again came to the
ground.  Further trial was postponed till the motor could be put
in better running condition.  The reporters had now, no doubt,
lost confidence in the machine, though their reports, in
kindness, concealed it.  Later, when they heard that we were
making flights of several minutes' duration, knowing that longer
flights had been made with airships, and not knowing any
essential difference between airships and flying machines, they
were but little interested.

'We had not been flying long in 1904 before we found that the
problem of equilibrium had not as yet been entirely solved. 
Sometimes, in making a circle, the machine would turn over
sidewise despite anything the operator could do, although, under
the same conditions in ordinary straight flight it could have
been righted in an instant.  In one flight, in 1905, while
circling round a honey locust-tree at a height of about 50 feet,
the machine suddenly began to turn up on one wing, and took a
course toward the tree.  The operator, not relishing the idea of
landing in a thorn tree, attempted to reach the ground.  The
left wing, however, struck the tree at a height of 10 or 12 feet
from the ground and carried away several branches; but the
flight, which had already covered a distance of six miles, was
continued to the starting point.

'The causes of these troubles--too technical for explanation
here--were not entirely overcome till the end of September,
1905.  The flights then rapidly increased in length, till
experiments were discontinued after October 5 on account of the
number of people attracted to the field. Although made on a
ground open on every side, and bordered on two sides by
much-travelled thoroughfares, with electric cars passing every
hour, and seen by all the people living in the neighbourhood for
miles around, and by several hundred others, yet these flights
have been made by some newspapers the subject of a great
&quot;mystery.&quot; '

Viewing their work from the financial side, the two brothers
incurred but little expense in the earlier gliding experiments,
and, indeed, viewed these only as recreation, limiting their
expenditure to that which two men might spend on any hobby. 
When they had once achieved successful power-driven flight, they
saw the possibilities of their work, and abandoned such other
business as had engaged their energies, sinking all their
capital in the development of a practical flying machine. 
Having, in 1905, improved their designs to such an extent that
they could consider their machine a practical aeroplane, they
devoted the years 1906 and 1907 to business negotiations and to
the construction of new machines, resuming flying experiments in
May of 1908 in order to test the ability of their machine to
meet the requirements of a contract they had made with the
United States Government, which required an aeroplane capable of
carrying two men, together with sufficient fuel supplies for a
flight of 125 miles at 40 miles per hour.  Practically similar
to the machine used in the experiments of 1905, the contract
aeroplane was fitted with a larger motor, and provision was made
for seating a passenger and also for allowing of the operator
assuming a sitting position, instead of lying prone.

Before leaving the work of the brothers to consider contemporary
events, it may be noted that they claimed--with justice--that
they were first to construct wings adjustable to different
angles of incidence on the right and left side in order to
control the balance of an aeroplane; the first to attain lateral
balance by adjusting wing-tips to respectively different angles
of incidence on the right and left sides, and the first to use a
vertical vane in combination with wing-tips, adjustable to
respectively different angles of incidence, in balancing and
steering an aeroplane.  They were first, too, to use a movable
vertical tail, in combination with wings adjustable to different
angles of incidence, in controlling the balance and direction of
an aeroplane.[*]

[*]Aeronautical Journal, No. 79.

A certain Henry M. Weaver, who went to see the work of the
brothers, writing in a letter which was subsequently read before
the Aero Club de France records that he had a talk in 1905 with
the farmer who rented the field in which the Wrights made their
flights.' On October 5th (1905) he was cutting corn in the next
field east, which is higher ground.  When he noticed the
aeroplane had started on its flight he remarked to his helper: 
&quot;Well, the boys are at it again,&quot; and kept on cutting corn, at
the same time keeping an eye on the great white form rushing
about its course.  &quot;I just kept on shocking corn,&quot; he continued,
&quot;until I got down to the fence, and the durned thing was still
going round.  I thought it would never stop.&quot; '

He was right.  The brothers started it, and it will never stop.

Mr Weaver also notes briefly the construction of the 1905 Wright
flier.  'The frame was made of larch wood-from tip to tip of the
wings the dimension was 40 feet.  The gasoline motor--a special
construction made by them--much the same, though, as the motor
on the Pope-Toledo automobile--was of from 12 to 15 horse-power. 
The motor weighed 240 lbs.  The frame was covered with ordinary
muslin of good quality.  No attempt was made to lighten the
machine; they simply built it strong enough to stand the shocks. 
The structure stood on skids or runners, like a sleigh.  These
held the frame high enough from the ground in alighting to
protect the blades of the propeller. Complete with motor, the
machine weighed 925 lbs.





Fortsetzung: [[Aeronautics_History_Vivian_1920 03 Evolution of the Aeroplane Years of Conquest|XII.  THE FIRST YEARS OF CONQUEST]]


==CONTENTS==

:Part I--THE EVOLUTION OF THE AEROPLANE
:   [[Aeronautics_History_Vivian_1920 01 Evolution of the Aeroplane Early Phase|I.  THE PERIOD OF LEGEND]]
: [[Aeronautics_History_Vivian_1920 01 Evolution of the Aeroplane Early Phase|II.  EARLY EXPERIMENTS]]
:  [[Aeronautics_History_Vivian_1920 01 Evolution of the Aeroplane Early Phase|III.  SIR GEORGE CAYLEY--THOMAS WALKER]]
:   [[Aeronautics_History_Vivian_1920 01 Evolution of the Aeroplane Early Phase|IV.  THE MIDDLE NINETEENTH CENTURY]]
:    [[Aeronautics_History_Vivian_1920 01 Evolution of the Aeroplane Early Phase|V.  WENHAM, LE BRIS, AND SOME OTHERS]]
:   [[Aeronautics_History_Vivian_1920 02 Evolution of the Aeroplane Age of the Giants|VI.  THE AGE OF THE GIANTS]]
:  [[Aeronautics_History_Vivian_1920 02 Evolution of the Aeroplane Age of the Giants|VII.  LILIENTHAL AND PILCHER]]
: [[Aeronautics_History_Vivian_1920 02 Evolution of the Aeroplane Age of the Giants|VIII.  AMERICAN GLIDING EXPERIMENTS]]
:   [[Aeronautics_History_Vivian_1920 02 Evolution of the Aeroplane Age of the Giants|IX.  NOT PROVEN]]
:    [[Aeronautics_History_Vivian_1920 02 Evolution of the Aeroplane Age of the Giants|X.  SAMUEL PIERPOINT LANGLEY]]
:   [[Aeronautics_History_Vivian_1920 02 Evolution of the Aeroplane Age of the Giants|XI.  THE WRIGHT BROTHERS]]
:  [[Aeronautics_History_Vivian_1920 03 Evolution of the Aeroplane Years of Conquest|XII.  THE FIRST YEARS OF CONQUEST]]
: [[Aeronautics_History_Vivian_1920 03 Evolution of the Aeroplane Years of Conquest|XIII.  FIRST FLIERS IN ENGLAND]]
:  [[Aeronautics_History_Vivian_1920 03 Evolution of the Aeroplane Years of Conquest|XIV.  RHEIMS, AND AFTER]]
:   [[Aeronautics_History_Vivian_1920 03 Evolution of the Aeroplane Years of Conquest|XV.  THE CHANNEL CROSSING]]
:  [[Aeronautics_History_Vivian_1920 03 Evolution of the Aeroplane Years of Conquest|XVI.  LONDON TO MANCHESTER]]
: [[Aeronautics_History_Vivian_1920 03 Evolution of the Aeroplane Years of Conquest|XVII.  A SUMMARY--TO 1911]]
:[[Aeronautics_History_Vivian_1920 04 Evolution of the Aeroplane Pre-war,WW1, Post-war to 1920|XVIII.  A SUMMARY--TO 1914]]
:  [[Aeronautics_History_Vivian_1920 04 Evolution of the Aeroplane Pre-war,WW1, Post-war to 1920|XIX.  THE WAR PERIOD--I]]
:   [[Aeronautics_History_Vivian_1920 04 Evolution of the Aeroplane Pre-war,WW1, Post-war to 1920|XX.  THE WAR PERIOD--II]]
:  [[Aeronautics_History_Vivian_1920 04 Evolution of the Aeroplane Pre-war,WW1, Post-war to 1920|XXI.  RECONSTRUCTION]]
: [[Aeronautics_History_Vivian_1920 04 Evolution of the Aeroplane Pre-war,WW1, Post-war to 1920|XXII.  1919-1920]]

:Part II--1903-1920: PROGRESS IN DESIGN
:    [[Aeronautics_History_Vivian_1920 05 Progress in Design|I.  THE BEGINNINGS]]
:   [[Aeronautics_History_Vivian_1920 05 Progress in Design|II.  MULTIPLICITY OF IDEAS]]
:  [[Aeronautics_History_Vivian_1920 05 Progress in Design|III.  PROGRESS ON STANDARDISED LINES]]
:   [[Aeronautics_History_Vivian_1920 05 Progress in Design|IV.  THE WAR PERIOD]]

:Part III--AEROSTATICS
:    [[Aeronautics_History_Vivian_1920 06 Aerostatics|I.  BEGINNINGS]]
:   [[Aeronautics_History_Vivian_1920 06 Aerostatics|II.  THE FIRST DIRIGIBLES]]
:  [[Aeronautics_History_Vivian_1920 06 Aerostatics|III.  SANTOS-DUMONT]]
:   [[Aeronautics_History_Vivian_1920 06 Aerostatics|IV.  THE MILITARY DIRIGIBLE]]
:    [[Aeronautics_History_Vivian_1920 06 Aerostatics|V.  BRITISH AIRSHIP  DESIGN]]
:   [[Aeronautics_History_Vivian_1920 06 Aerostatics|VI.  THE AIRSHIP  COMMERCIALLY]]
:  [[Aeronautics_History_Vivian_1920 06 Aerostatics|VII.  KITE  BALLOONS]]

:PART IV--ENGINE DEVELOPMENT
:    [[Aeronautics_History_Vivian_1920 07 Engine Development|I.  THE VERTICAL TYPE]]
:   [[Aeronautics_History_Vivian_1920 07 Engine Development|II.  THE VEE TYPE]]
:  [[Aeronautics_History_Vivian_1920 07 Engine Development|III.  THE RADIAL TYPE]]
:   [[Aeronautics_History_Vivian_1920 07 Engine Development|IV.  THE ROTARY TYPE]]
:    [[Aeronautics_History_Vivian_1920 07 Engine Development|V.  THE HORIZONTALLY-OPPOSED ENGINE]]
:   [[Aeronautics_History_Vivian_1920 07 Engine Development|VI.  THE TWO-STROKE CYCLE ENGINE]]
:  [[Aeronautics_History_Vivian_1920 07 Engine Development|VII.  ENGINES OF THE WAR  PERIOD]]

:[[Aeronautics_History_Vivian_1920 08 Appendixes|APPENDICES]]


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