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A HISTORY OF AERONAUTICS
[Illustration: Trial of full-size Langley Aerodrome, 8th December, 1903.
Langley Memoir on Mechanical Flight, Smithsonian Institution,
Washington.
_Frontispiece._
]
A
History of Aeronautics
_by_
E. CHARLES VIVIAN
WITH A SECTION ON PROGRESS IN
AEROPLANE DESIGN
_by_
LIEUT.-COL. W. LOCKWOOD MARSH, O.B.E.
[Illustration]
NEW YORK
HARCOURT, BRACE AND COMPANY
1921
_To_
MY WITNESS
OCT. 21ST 1919
V.
FOREWORD
Although successful heavier-than-air flight is less than two decades
old, and successful dirigible propulsion antedates it by a very
short period, the mass of experiment and accomplishment renders any
one-volume history of the subject a matter of selection. In addition to
the restrictions imposed by space limits, the material for compilation
is fragmentary, and, in many cases, scattered through periodical and
other publications. Hitherto, there has been no attempt at furnishing a
detailed account of how the aeroplane and the dirigible of to-day came
to being, but each author who has treated the subject has devoted his
attention to some special phase or section. The principal exception
to this rule--Hildebrandt--wrote in 1906, and a good many of his
statements are inaccurate, especially with regard to heavier-than-air
experiment.
Such statements as are made in this work are, where possible, given
with acknowledgment to the authorities on which they rest. Further
acknowledgment is due to Lieut.-Col. Lockwood Marsh, not only for
the section on aeroplane development which he has contributed to the
work, but also for his kindly assistance and advice in connection with
the section on aerostation. The author’s thanks are also due to the
Royal Aeronautical Society for free access to its valuable library of
aeronautical literature, and to Mr A. Vincent Clarke for permission to
make use of his notes on the development of the aero engine.
In this work is no claim to originality--it has been a matter mainly of
compilation, and some stories, notably those of the Wright Brothers and
of Santos Dumont, are better told in the words of the men themselves
than any third party could tell them. The author claims, however, that
this is the first attempt at recording the facts of development and
stating, as fully as is possible in the compass of a single volume, how
flight and aerostation have evolved. The time for a critical history of
the subject is not yet.
In the matter of illustrations, it has been found very difficult to
secure suitable material. Even the official series of photographs
of aeroplanes in the war period is curiously incomplete, and the
methods of censorship during that period prevented any complete series
being privately collected. Omissions in this respect will probably
be remedied in future editions of the work, as fresh material is
constantly being located.
E. C. V.
_October, 1920._
CONTENTS
PART I--THE EVOLUTION OF THE AEROPLANE
CHAP. PAGE
I. THE PERIOD OF LEGEND 3
II. EARLY EXPERIMENTS 15
III. SIR GEORGE CAYLEY--THOMAS WALKER 43
IV. THE MIDDLE NINETEENTH CENTURY 56
V. WENHAM, LE BRIS, AND SOME OTHERS 71
VI. THE AGE OF THE GIANTS 83
VII. LILIENTHAL AND PILCHER 95
VIII. AMERICAN GLIDING EXPERIMENTS 107
IX. NOT PROVEN 121
X. SAMUEL PIERPOINT LANGLEY 133
XI. THE WRIGHT BROTHERS 145
XII. THE FIRST YEARS OF CONQUEST 176
XIII. FIRST FLIERS IN ENGLAND 188
XIV. RHEIMS, AND AFTER 199
XV. THE CHANNEL CROSSING 211
XVI. LONDON TO MANCHESTER 217
XVII. A SUMMARY--TO 1911 221
XVIII. A SUMMARY--TO 1914 233
XIX. THE WAR PERIOD--I 246
XX. THE WAR PERIOD--II 259
XXI. RECONSTRUCTION 264
XXII. 1919–1920 270
PART II--1903–1920: PROGRESS IN DESIGN
I. THE BEGINNINGS 277
II. MULTIPLICITY OF IDEAS 289
III. PROGRESS ON STANDARDISED LINES 296
IV. THE WAR PERIOD 306
PART III--AEROSTATICS
I. BEGINNINGS 317
II. THE FIRST DIRIGIBLES 331
III. SANTOS-DUMONT 342
IV. THE MILITARY DIRIGIBLE 348
V. BRITISH AIRSHIP DESIGN 359
VI. THE AIRSHIP COMMERCIALLY 372
VII. KITE BALLOONS 376
PART IV--ENGINE DEVELOPMENT
I. THE VERTICAL TYPE 383
II. THE VEE TYPE 404
III. THE RADIAL TYPE 417
IV. THE ROTARY TYPE 428
V. THE HORIZONTALLY-OPPOSED ENGINE 440
VI. THE TWO-STROKE CYCLE ENGINE 447
VII. ENGINES OF THE WAR PERIOD 458
APPENDICES 469
A SHORT BIBLIOGRAPHY OF AERONAUTICS 504
PART I
THE EVOLUTION OF THE AEROPLANE
I
THE PERIOD OF LEGEND
The blending of fact and fancy which men call legend reached its
fullest and richest expression in the golden age of Greece, and thus
it is to Greek mythology that one must turn for the best form of
any legend which foreshadows history. Yet the prevalence of legends
regarding flight, existing in the records of practically every race,
shows that this form of transit was a dream of many peoples--man always
wanted to fly, and imagined means of flight.
In this age of steel, a very great part of the inventive genius of man
has gone into devices intended to facilitate transport, both of men and
goods, and the growth of civilisation is in reality the facilitation of
transit, improvement of the means of communication. He was a genius who
first hoisted a sail on a boat and saved the labour of rowing; equally,
he who first harnessed ox or dog or horse to a wheeled vehicle was a
genius--and these looked up, as men have looked up from the earliest
days of all, seeing that the birds had solved the problem of transit
far more completely than themselves. So it must have appeared, and
there is no age in history in which some dreamers have not dreamed
of the conquest of the air; if the caveman had left records, these
would without doubt have showed that he, too, dreamed this dream. His
main aim, probably, was self-preservation; when the dinosaur looked
round the corner, the prehistoric bird got out of the way in his usual
manner, and prehistoric man--such of him as succeeded in getting out
of the way after his fashion--naturally envied the bird, and concluded
that as lord of creation in a doubtful sort of way he ought to have
equal facilities. He may have tried, like Simon the Magician, and other
early experimenters, to improvise those facilities; assuming that he
did, there is the groundwork of much of the older legend with regard to
men who flew, since, when history began, legends would be fashioned out
of attempts and even the desire to fly, these being compounded of some
small ingredient of truth and much exaggeration and addition.
In a study of the first beginnings of the art, it is worth while to
mention even the earliest of the legends and traditions, for they
show the trend of men’s minds and the constancy of this dream that
has become reality in the twentieth century. In one of the oldest
records of the world, the Indian classic _Mahabarata_, it is stated
that ‘Krishna’s enemies sought the aid of the demons, who built an
aerial chariot with sides of iron and clad with wings. The chariot was
driven through the sky till it stood over Dwarakha, where Krishna’s
followers dwelt, and from there it hurled down upon the city missiles
that destroyed everything on which they fell.’ Here is pure fable, not
legend, but still a curious forecast of twentieth century bombs from a
rigid dirigible. It is to be noted in this case, as in many, that the
power to fly was an attribute of evil, not of good--it was the demons
who built the chariot, even as at Friedrichshavn. Mediæval legend,
in nearly every case, attributes flight to the aid of evil powers,
and incites well-disposed people to stick to the solid earth--though,
curiously enough, the pioneers of mediæval times were very largely of
priestly type, as witness the monk of Malmesbury.
The legends of the dawn of history, however, distribute the power of
flight with less of prejudice. Egyptian sculpture gives the figure
of winged men; the British Museum has made the winged Assyrian bulls
familiar to many, and both the cuneiform records of Assyria and the
hieroglyphs of Egypt record flights that in reality were never made.
The desire fathered the story then, and until Clement Ader either
hopped with his _Avion_, as is persisted by his critics, or flew, as is
claimed by his friends.
While the origin of many legends is questionable, that of others is
easy enough to trace, though not to prove. Among the credulous the
significance of the name of a people of Asia Minor, the Capnobates,
‘those who travel by smoke,’ gave rise to the assertion that Mongolfier
was not first in the field--or rather in the air--since surely this
people must have been responsible for the first hot-air balloons. Far
less questionable is the legend of Icarus, for here it is possible
to trace a foundation of fact in the story. Such a tribe as Dædalus
governed could have had hardly any knowledge of the rudiments of
science, and even their ruler, seeing how easy it is for birds to
sustain themselves in the air, might be excused for believing that he,
if he fashioned wings for himself, could use them. In that belief, let
it be assumed, Dædalus made his wings; the boy, Icarus, learning that
his father had determined on an attempt at flight, secured the wings
and fastened them to his own shoulders. A cliff seemed the likeliest
place for a ‘take-off,’ and Icarus leaped from the cliff edge only to
find that the possession of wings was not enough to assure flight to a
human being. The sea that to this day bears his name witnesses that he
made the attempt and perished by it.
In this is assumed the bald story, from which might grow the legend of
a wise king who ruled a peaceful people--‘judged, sitting in the sun,’
as Browning has it, and fashioned for himself wings with which he flew
over the sea and where he would, until the prince, Icarus, desired
to emulate him. Icarus, fastening the wings to his shoulders with
wax, was so imprudent as to fly too near the sun, when the wax melted
and he fell, to lie mourned of water-nymphs on the shores of waters
thenceforth Icarian. Between what we have assumed to be the base of
fact, and the legend which has been invested with such poetic grace in
Greek story, there is no more than a century or so of re-telling might
give to any event among a people so simple and yet so given to imagery.
We may set aside as pure fable the stories of the winged horse of
Perseus, and the flights of Hermes as messenger of the gods. With
them may be placed the story of Empedocles, who failed to take Etna
seriously enough, and found himself caught by an eruption while within
the crater, so that, flying to safety in some hurry, he left behind
but one sandal to attest that he had sought refuge in space--in all
probability, if he escaped at all, he flew, but not in the sense that
the aeronaut understands it. But, bearing in mind the many men who
tried to fly in historic times, the legend of Icarus and Dædalus, in
spite of the impossible form in which it is presented, may rank with
the story of the Saracen of Constantinople, or with that of Simon the
Magician. A simple folk would naturally idealise the man and magnify
his exploit, as they magnified the deeds of some strong man to make
the legends of Hercules, and there, full-grown from a mere legend, is
the first record of a pioneer of flying. Such a theory is not nearly
so fantastic as that which makes the Capnobates, on the strength of
their name, the inventors of hot-air balloons. However it may be, both
in story and in picture, Icarus and his less conspicuous father have
inspired the Caucasian mind, and the world is the richer for them.
Of the unsupported myths--unsupported, that is, by even a shadow of
probability--there is no end. Although Latin legend approaches nearer
to fact than the Greek in some cases, in others it shows a disregard
for possibilities which renders it of far less account. Thus Diodorus
of Sicily relates that one Abaris travelled round the world on an arrow
of gold, and Cassiodorus and Glycas and their like told of mechanical
birds that flew and sang and even laid eggs. More credible is the story
of Aulus Gellius, who in his _Attic Nights_ tells how Archytas, four
centuries prior to the opening of the Christian era, made a wooden
pigeon that actually flew by means of a mechanism of balancing weights
and the breath of a mysterious spirit hidden within it. There may yet
arise one credulous enough to state that the mysterious spirit was
precursor of the internal combustion engine, but, however that may
be, the pigeon of Archytas almost certainly existed, and perhaps it
actually glided or flew for short distances--or else Aulus Gellius was
an utter liar, like Cassiodorus and his fellows. In far later times a
certain John Muller, better known as Regiomontanus, is stated to have
made an artificial eagle which accompanied Charles V. on his entry
to and exit from Nuremberg, flying above the royal procession. But,
since Muller died in 1436 and Charles was born in 1500, Muller may be
ruled out from among the pioneers of mechanical flight, and it may be
concluded that the historian of this event got slightly mixed in his
dates.
Thus far, we have but indicated how one may draw from the richest
stores from which the Aryan mind draws inspiration, the Greek and Latin
mythologies and poetic adaptations of history. The existing legends of
flight, however, are not thus to be localised, for with two possible
exceptions they belong to all the world and to every civilisation,
however primitive. The two exceptions are the Aztec and the Chinese;
regarding the first of these, the Spanish _conquistadores_ destroyed
such civilisation as existed in Tenochtitlan so thoroughly that, if
legend of flight was among the Aztec records, it went with the rest; as
to the Chinese, it is more than passing strange that they, who claim to
have known and done everything while the first of history was shaping,
even to antedating the discovery of gunpowder that was _not_ made by
Roger Bacon, have not yet set up a claim to successful handling of a
monoplane some four thousand years ago, or at least to the patrol of
the Gulf of Korea and the Mongolian frontier by a forerunner of the
‘blimp.’
The Inca civilisation of Peru yields up a myth akin to that of Icarus,
which tells how the chieftain Ayar Utso grew wings and visited the
sun--it was from the sun, too, that the founders of the Peruvian Inca
dynasty, Manco Capac and his wife Mama Huella Capac, flew to earth near
Lake Titicaca, to make the only successful experiment in pure tyranny
that the world has ever witnessed. Teutonic legend gives forth Wieland
the Smith, who made himself a dress with wings and, clad in it, rose
and descended against the wind and in spite of it. Indian mythology, in
addition to the story of the demons and their rigid dirigible, already
quoted, gives the story of Hanouam, who fitted himself with wings by
means of which he sailed in the air and, according to his desire,
landed in the sacred Lauka. Bladud, the ninth king of Britain, is said
to have crowned his feats of wizardry by making himself wings and
attempting to fly--but the effort cost him a broken neck. Bladud may
have been as mythic as Uther, and again he may have been a very early
pioneer. The Finnish epic, ‘Kalevala,’ tells how Ilmarinen the Smith
‘forged an eagle of fire,’ with ‘boat’s walls between the wings,’ after
which he ‘sat down on the bird’s back and bones,’ and flew.
Pure myths, these, telling how the desire to fly was characteristic of
every age and every people, and how, from time to time, there arose
an experimenter bolder than his fellows, who made some attempt to
translate desire into achievement. And the spirit that animated these
pioneers, in a time when things new were accounted things accursed,
for the most part, has found expression in this present century in the
utter daring and disregard of both danger and pain that stamps the
flying man, a type of humanity differing in spirit from his earth-bound
fellows as fully as the soldier differs from the priest.
Throughout mediæval times, records attest that here and there some
man believed in and attempted flight, and at the same time it is clear
that such were regarded as in league with the powers of evil. There is
the half-legend, half-history of Simon the Magician, who, in the third
year of the reign of Nero announced that he would raise himself in
the air, in order to assert his superiority over St Paul. The legend
states that by the aid of certain demons whom he had prevailed on to
assist him, he actually lifted himself in the air--but St Paul prayed
him down again. He slipped through the claws of the demons and fell
headlong on the Forum at Rome, breaking his neck. The ‘demons’ may have
been some primitive form of hot-air balloon, or a glider with which
the magician attempted to rise into the wind; more probably, however,
Simon threatened to ascend and made the attempt with apparatus as
unsuitable as Bladud’s wings, paying the inevitable penalty. Another
version of the story gives St Peter instead of St Paul as the one whose
prayers foiled Simon--apart from the identity of the apostle, the two
accounts are similar, and both define the attitude of the age toward
investigation and experiment in things untried.
Another and later circumstantial story, with similar evidence of some
fact behind it, is that of the Saracen of Constantinople, who, in the
reign of the Emperor Comnenus--some little time before Norman William
made Saxon Harold swear away his crown on the bones of the saints at
Rouen--attempted to fly round the hippodrome at Constantinople, having
Comnenus among the great throng who gathered to witness the feat.
The Saracen chose for his starting-point a tower in the midst of the
hippodrome, and on the top of the tower he stood, clad in a long
white robe which was stiffened with rods so as to spread and catch the
breeze, waiting for a favourable wind to strike on him. The wind was so
long in coming that the spectators grew impatient. ‘Fly, O Saracen!’
they called to him. ‘Do not keep us waiting so long while you try the
wind!’ Comnenus, who had present with him the Sultan of the Turks, gave
it as his opinion that the experiment was both dangerous and vain, and,
possibly in an attempt to controvert such statement, the Saracen leaned
into the wind and ‘rose like a bird’ at the outset. But the record of
Cousin, who tells the story in his _Histoire de Constantinople_, states
that ‘the weight of his body having more power to drag him down than
his artificial wings had to sustain him, he broke his bones, and his
evil plight was such that he did not long survive.’
Obviously, the Saracen was anticipating Lilienthal and his gliders
by some centuries; like Simon, a genuine experimenter--both legends
bear the impress of fact supporting them. Contemporary with him, and
belonging to the history rather than the legends of flight, was Oliver,
the monk of Malmesbury, who in the year 1065 made himself wings after
the pattern of those supposed to have been used by Dædalus, attaching
them to his hands and feet and attempting to fly with them. Twysden, in
his _Historiæ Anglicanæ Scriptores X_, sets forth the story of Oliver,
who chose a high tower as his starting-point, and launched himself in
the air. As a matter of course, he fell, permanently injuring himself,
and died some time later.
After these, a gap of centuries, filled in by impossible stories of
magical flight by witches, wizards, and the like--imagination was
fertile in the dark ages, but the ban of the church was on all attempt
at scientific development, especially in such a matter as the conquest
of the air. Yet there were observers of nature who argued that since
birds could raise themselves by flapping their wings, man had only
to make suitable wings, flap them, and he too would fly. As early as
the thirteenth century Roger Bacon, the scientific friar of unbounded
inquisitiveness and not a little real genius, announced that there
could be made ‘some flying instrument, so that a man sitting in the
middle and turning some mechanism may put in motion some artificial
wings which may beat the air like a bird flying.’ But being a cautious
man, with a natural dislike for being burnt at the stake as a
necromancer through having put forward such a dangerous theory, Roger
added, ‘not that I ever knew a man who had such an instrument, but I
am particularly acquainted with the man who contrived one.’ This might
have been a lame defence if Roger had been brought to trial as addicted
to black arts; he seems to have trusted to the inadmissibility of
hearsay evidence.
Some four centuries later there was published a book entitled _Perugia
Augusta_, written by one C. Crispolti of Perugia--the date of the work
in question is 1648. In it is recorded that ‘one day, towards the close
of the fifteenth century, whilst many of the principal gentry had come
to Perugia to honour the wedding of Giovanni Paolo Baglioni, and some
lancers were riding down the street by his palace, Giovanni Baptisti
Danti unexpectedly and by means of a contrivance of wings that he
had constructed proportionate to the size of his body took off from
the top of a tower near by, and with a horrible hissing sound flew
successfully across the great Piazza, which was densely crowded. But
(oh, horror of an unexpected accident!) he had scarcely flown three
hundred paces on his way to a certain point when the mainstay of the
left wing gave way, and, being unable to support himself with the right
alone, he fell on a roof and was injured in consequence. Those who
saw not only this flight, but also the wonderful construction of the
framework of the wings, said--and tradition bears them out--that he
several times flew over the waters of Lake Thrasimene to learn how he
might gradually come to earth. But, notwithstanding his great genius,
he never succeeded.’
This reads circumstantially enough, but it may be borne in mind that
the date of writing is more than half a century later than the time of
the alleged achievement--the story had had time to round itself out.
Danti, however, is mentioned by a number of writers, one of whom states
that the failure of his experiment was due to the prayers of some
individual of a conservative turn of mind, who prayed so vigorously
that Danti fell appropriately enough on a church and injured himself
to such an extent as to put an end to his flying career. That Danti
experimented, there is little doubt, in view of the volume of evidence
on the point, but the darkness of the Middle Ages hides the real truth
as to the results of his experiments. If he had actually flown over
Thrasimene, as alleged, then in all probability both Napoleon and
Wellington would have had air scouts at Waterloo.
Danti’s story may be taken as fact or left as fable, and with it the
period of legend or vague statement may be said to end--the rest
is history, both of genuine experimenters and of charlatans. Such
instances of legend as are given here are not a tithe of the whole, but
there is sufficient in the actual history of flight to bar out more
than this brief mention of the legends, which, on the whole, go farther
to prove man’s desire to fly than his study and endeavour to solve the
problems of the air.
II
EARLY EXPERIMENTS
So far, the stories of the development of flight are either legendary
or of more or less doubtful authenticity, even including that of Danti,
who, although a man of remarkable attainments in more directions
than that of attempted flight, suffers--so far as reputation is
concerned--from the inexactitudes of his chroniclers; he may have
soared over Thrasimene, as stated, or a mere hop with an ineffectual
glider may have grown with the years to a legend of gliding flight. So
far, too, there is no evidence of the study that the conquest of the
air demanded; such men as made experiments either launched themselves
in the air from some height with made-up wings or other apparatus,
and paid the penalty, or else constructed some form of machine which
would not leave the earth, and then gave up. Each man followed his
own way, and there was no attempt--without the printing press and the
dissemination of knowledge there was little possibility of attempt--on
the part of any one to benefit by the failures of others.
Legend and doubtful history carries up to the fifteenth century, and
then came Leonardo da Vinci, first student of flight whose work endures
to the present day. The world knows da Vinci as artist; his age knew
him as architect, engineer, artist, and scientist in an age when
science was a single study, comprising all knowledge from mathematics
to medicine. He was, of course, in league with the devil, for in no
other way could his range of knowledge and observation be explained
by his contemporaries; he left a _Treatise on the Flight of Birds_
in which are statements and deductions that had to be rediscovered
when the _Treatise_ had been forgotten--da Vinci anticipated modern
knowledge as Plato anticipated modern thought, and blazed the first
broad trail toward flight.
One Cuperus, who wrote a _Treatise on the Excellence of Man_, asserted
that da Vinci translated his theories into practice, and actually flew,
but the statement is unsupported. That he made models, especially on
the helicopter principle, is past question; these were made of paper
and wire, and actuated by springs of steel wire, which caused them to
lift themselves in the air. It is, however, in the theories which he
put forward that da Vinci’s investigations are of greatest interest;
these prove him a patient as well as a keen student of the principles
of flight, and show that his manifold activities did not prevent him
from devoting some lengthy periods to observations of bird flight.
‘A bird,’ he says in his _Treatise_, ‘is an instrument working
according to mathematical law, which instrument it is within the
capacity of man to reproduce with all its movements, but not with
a corresponding degree of strength, though it is deficient only in
power of maintaining equilibrium. We may say, therefore, that such an
instrument constructed by man is lacking in nothing except the life of
the bird, and this life must needs be supplied from that of man. The
life which resides in the bird’s members will, without doubt, better
conform to their needs than will that of a man which is separated
from them, and especially in the almost imperceptible movements which
produce equilibrium. But since we see that the bird is equipped for
many apparent varieties of movement, we are able from this experience
to deduce that the most rudimentary of these movements will be capable
of being comprehended by man’s understanding, and that he will to
a great extent be able to provide against the destruction of that
instrument of which he himself has become the living principle and the
propeller.’
In this is the definite belief of da Vinci that man is capable of
flight, together with a far more definite statement of the principles
by which flight is to be achieved than any which had preceded it--and
for that matter, than many that have succeeded it. Two further extracts
from his work will show the exactness of his observations:--
‘When a bird which is in equilibrium throws the centre of resistance of
the wings behind the centre of gravity, then such a bird will descend
with its head downward. This bird which finds itself in equilibrium
shall have the centre of resistance of the wings more forward than the
bird’s centre of gravity; then such a bird will fall with its tail
turned toward the earth.’
And again: ‘A man, when flying, shall be free from the waist up, that
he may be able to keep himself in equilibrium as he does in a boat, so
that the centre of his gravity and of the instrument may set itself in
equilibrium and change when necessity requires it to the changing of
the centre of its resistance.’
Here, in this last quotation, are the first beginnings of the inherent
stability which proved so great an advance in design, in this
twentieth century. But the extracts given do not begin to exhaust the
range of da Vinci’s observations and deductions. With regard to bird
flight, he observed that so long as a bird keeps its wings outspread
it cannot fall directly to earth, but must glide down at an angle
to alight--a small thing, now that the principle of the plane in
opposition to the air is generally grasped, but da Vinci had to find
it out. From observation he gathered how a bird checks its own speed
by opposing tail and wing surface to the direction of flight, and
thus alights at the proper ‘landing speed.’ He proved the existence
of upward air currents by noting how a bird takes off from level
earth with wings outstretched and motionless, and, in order to get an
efficient substitute for the natural wing, he recommended that there
be used something similar to the membrane of the wing of a bat--from
this to the doped fabric of an aeroplane wing is but a small step, for
both are equally impervious to air. Again, da Vinci recommended that
experiments in flight be conducted at a good height from the ground,
since, if equilibrium be lost through any cause, the height gives time
to regain it. This recommendation, by the way, received ample support
in the training areas of war pilots.
Man’s muscles, said da Vinci, are fully sufficient to enable him to
fly, for the larger birds, he noted, employ but a small part of their
strength in keeping themselves afloat in the air--by this theory he
attempted to encourage experiment, just as, when his time came, Borelli
reached the opposite conclusion and discouraged it. That Borelli was
right--so far--and da Vinci wrong, detracts not at all from the repute
of the earlier investigator, who had but the resources of his age to
support investigations conducted in the spirit of ages after.
His chief practical contributions to the science of flight--apart
from numerous drawings which have still a value--are the helicopter
or lifting screw, and the parachute. The former, as already noted,
he made and proved effective in model form, and the principle which
he demonstrated is that of the helicopter of to-day, on which sundry
experimenters work spasmodically, in spite of the success of the plane
with its driving propeller. As to the parachute, the idea was doubtless
inspired by observation of the effect a bird produced by pressure of
its wings against the direction of flight.
Da Vinci’s conclusions, and his experiments, were forgotten easily by
most of his contemporaries; his _Treatise_ lay forgotten for nearly
four centuries, overshadowed, mayhap, by his other work. There was,
however, a certain Paolo Guidotti of Lucca, who lived in the latter
half of the sixteenth century, and who attempted to carry da Vinci’s
theories--one of them, at least, into practice. For this Guidotti, who
was by profession an artist and by inclination an investigator, made
for himself wings, of which the framework was of whalebone; these he
covered with feathers, and with them made a number of gliding flights,
attaining considerable proficiency. He is said in the end to have made
a flight of about four hundred yards, but this attempt at solving the
problem ended on a house roof, where Guidotti broke his thigh bone.
After that, apparently, he gave up the idea of flight, and went back to
painting.
One other, a Venetian architect named Veranzio, studied da Vinci’s
theory of the parachute, and found it correct, if contemporary records
and even pictorial presentment are correct. Da Vinci showed his
conception of a parachute as a sort of inverted square bag; Veranzio
modified this to a ‘sort of square sail extended by four rods of equal
size and having four cords attached at the corners,’ by means of which
‘a man could without danger throw himself from the top of a tower or
any high place. For though at the moment there may be no wind, yet the
effort of his falling will carry up the wind, which the sail will hold,
by which means he does not fall suddenly but descends little by little.
The size of the sail should be measured to the man.’ By this last,
evidently, Veranzio intended to convey that the sheet must be of such
content as would enclose sufficient air to support the weight of the
parachutist.
Veranzio made his experiments about 1617–1618, but, naturally, they
carried him no farther than the mere descent to earth, and since a
descent is merely a descent, it is to be conjectured that he soon got
tired of dropping from high roofs, and took to designing architecture
instead of putting it to such a use. With the end of his experiments
the work of da Vinci in relation to flying became neglected for nearly
four centuries.
Apart from these two experimenters, there is little to record in the
matter either of experiment or study until the seventeenth century.
Francis Bacon, it is true, wrote about flying in his _Sylva Sylvarum_,
and mentioned the subject in the _New Atlantis_, but, except for
the insight that he showed even in superficial mention of any
specific subject, he does not appear to have made attempt at serious
investigation. ‘Spreading of Feathers, thin and close and in great
breadth will likewise bear up a great Weight,’ says Francis, ‘being
even laid without Tilting upon the sides.’ But a lesser genius could
have told as much, even in that age, and though the great Sir Francis
is sometimes adduced as one of the early students of the problems of
flight, his writings will not sustain the reputation.
The seventeenth century, however, gives us three names, those of
Borelli, Lana, and Robert Hooke, all of which take definite place in
the history of flight. Borelli ranks as one of the great figures in
the study of aeronautical problems, in spite of erroneous deductions
through which he arrived at a purely negative conclusion with regard to
the possibility of human flight.
Borelli was a versatile genius. Born in 1608, he was practically
contemporary with Francesco Lana, and there is evidence that he either
knew or was in correspondence with many prominent members of the Royal
Society of Great Britain, more especially with John Collins, Dr Wallis,
and Henry Oldenburgh, the then Secretary of the Society. He was author
of a long list of scientific essays, two of which only are responsible
for his fame, viz., _Theorice Medicæarum Planetarum_, published in
Florence, and the better known posthumous _De Motu Animalium_. The
first of these two is an astronomical study in which Borelli gives
evidence of an instinctive knowledge of gravitation, though no definite
expression is given of this. The second work, _De Motu Animalium_,
deals with the mechanical action of the limbs of birds and animals
and with a theory of the action of the internal organs. A section of
the first part of this work, called _De Volatu_, is a study of bird
flight; it is quite independent of Da Vinci’s earlier work, which had
been forgotten and remained unnoticed until near on the beginning of
practical flight.
Marey, in his work, _La Machine Animale_, credits Borelli with the
first correct idea of the mechanism of flight. He says: ‘Therefore we
must be allowed to render to the genius of Borelli the justice which is
due to him, and only claim for ourselves the merit of having furnished
the experimental demonstration of a truth already suspected.’ In fact,
all subsequent studies on this subject concur in making Borelli the
first investigator who illustrated the purely mechanical theory of the
action of a bird’s wings.
Borelli’s study is divided into a series of propositions in which he
traces the principles of flight, and the mechanical actions of the
wings of birds. The most interesting of these are the propositions
in which he sets forth the method in which birds move their wings
during flight and the manner in which the air offers resistance to the
stroke of the wing. With regard to the first of these two points he
says: ‘When birds in repose rest on the earth their wings are folded
up close against their flanks, but when wishing to start on their
flight they first bend their legs and leap into the air. Whereupon
the joints of their wings are straightened out to form a straight
line at right angles to the lateral surface of the breast, so that
the two wings, outstretched, are placed, as it were, like the arms
of a cross to the body of the bird. Next, since the wings with their
feathers attached form almost a plane surface, they are raised slightly
above the horizontal, and with a most quick impulse beat down in a
direction almost perpendicular to the wing-plane, upon the underlying
air; and to so intense a beat the air, notwithstanding it to be
fluid, offers resistance, partly by reason of its natural inertia,
which seeks to retain it at rest, and partly because the particles
of the air, compressed by the swiftness of the stroke, resist this
compression by their elasticity, just like the hard ground. Hence
the whole mass of the bird rebounds, making a fresh leap through the
air; whence it follows that flight is simply a motion composed of
successive leaps accomplished through the air. And I remark that a
wing can easily beat the air in a direction almost perpendicular to
its plane surface, although only a single one of the corners of the
humerus bone is attached to the scapula, the whole extent of its base
remaining free and loose, while the greater transverse feathers are
joined to the lateral skin of the thorax. Nevertheless the wing can
easily revolve about its base like unto a fan. Nor are there lacking
tendon ligaments which restrain the feathers and prevent them from
opening farther, in the same fashion that sheets hold in the sails of
ships. No less admirable is nature’s cunning in unfolding and folding
the wings upwards, for she folds them not laterally, but by moving
upwards edgewise the osseous parts wherein the roots of the feathers
are inserted; for thus, without encountering the air’s resistance the
upward motion of the wing surface is made as with a sword, hence they
can be uplifted with but small force. But thereafter when the wings
are twisted by being drawn transversely and by the resistance of the
air, they are flattened as has been declared and will be made manifest
hereafter.’
Then with reference to the resistance to the air of the wings he
explains: ‘The air when struck offers resistance by its elastic virtue
through which the particles of the air compressed by the wing-beat
strive to expand again. Through these two causes of resistance the
downward beat of the wing is not only opposed, but even caused to
recoil with a reflex movement; and these two causes of resistance
ever increase the more the down stroke of the wing is maintained and
accelerated. On the other hand, the impulse of the wing is continuously
diminished and weakened by the growing resistance. Hereby the force of
the wing and the resistance become balanced; so that, manifestly, the
air is beaten by the wing with the same force as the resistance to the
stroke.’
He concerns himself also with the most difficult problem that confronts
the flying man of to-day, namely, landing effectively, and his remarks
on this subject would be instructive even to an air pilot of these
days: ‘Now the ways and means by which the speed is slackened at the
end of a flight are these. The bird spreads its wings and tail so that
their concave surfaces are perpendicular to the direction of motion; in
this way, the spreading feathers, like a ship’s sail, strike against
the still air, check the speed, and so that most of the impetus may be
stopped, the wings are flapped quickly and strongly forward, inducing a
contrary motion, so that the bird absolutely or very nearly stops.’
At the end of his study Borelli came to a conclusion which militated
greatly against experiment with any heavier-than-air apparatus, until
well on into the nineteenth century, for having gone thoroughly into
the subject of bird flight he states distinctly in his last proposition
on the subject that ‘It is impossible that men should be able to fly
craftily by their own strength.’ This statement, of course, remains
true up to the present day, for no man has yet devised the means by
which he can raise himself in the air and maintain himself there by
mere muscular effort.
From the time of Borelli up to the development of the steam engine it
may be said that flight by means of any heavier-than-air apparatus was
generally regarded as impossible, and apart from certain deductions
which a little experiment would have shown to be doomed to failure,
this method of flight was not followed up. It is not to be wondered
at, when Borelli’s exaggerated estimate of the strength expended by
birds in proportion to their weight is borne in mind; he alleged
that the motive force in birds’ wings is 10,000 times greater than
the resistance of their weight, and with regard to human flight he
remarks:--
‘When, therefore, it is asked whether men may be able to fly by their
own strength, it must be seen whether the motive power of the pectoral
muscles (the strength of which is indicated and measured by their size)
is proportionately great, as it is evident that it must exceed the
resistance of the weight of the whole human body 10,000 times, together
with the weight of enormous wings which should be attached to the arms.
And it is clear that the motive power of the pectoral muscles in men
is much less than is necessary for flight, for in birds the bulk and
weight of the muscles for flapping the wings are not less than a sixth
part of the entire weight of the body. Therefore, it would be necessary
that the pectoral muscles of a man should weigh more than a sixth
part of the entire weight of his body; so also the arms, by flapping
with the wings attached, should be able to exert a power 10,000 times
greater than the weight of the human body itself. But they are far
below such excess, for the aforesaid pectoral muscles do not equal
a hundredth part of the entire weight of a man. Wherefore either the
strength of the muscles ought to be increased or the weight of the
human body must be decreased, so that the same proportion obtains in
it as exists in birds. Hence it is deducted that the Icarian invention
is entirely mythical because impossible, for it is not possible either
to increase a man’s pectoral muscles or to diminish the weight of the
human body; and whatever apparatus is used, although it is possible to
increase the momentum, the velocity or the power employed can never
equal the resistance; and therefore wing flapping by the contraction of
muscles cannot give out enough power to carry up the heavy body of a
man.’
It may be said that practically all the conclusions which Borelli
reached in his study were negative. Although contemporary with Lana,
he perceived the one factor which rendered Lana’s project for flight
by means of vacuum globes an impossibility--he saw that no globe
could be constructed sufficiently light for flight, and at the same
time sufficiently strong to withstand the pressure of the outside
atmosphere. He does not appear to have made any experiments in flying
on his own account, having, as he asserts most definitely, no faith in
any invention designed to lift man from the surface of the earth. But
his work, from which only the foregoing short quotations can be given,
is, nevertheless, of indisputable value, for he settled the mechanics
of bird flight, and paved the way for those later investigators who
had, first, the steam engine, and later the internal combustion
engine--two factors in mechanical flight which would have seemed as
impossible to Borelli as would wireless telegraphy to a student of
Napoleonic times. On such foundations as his age afforded Borelli built
solidly and well, so that he ranks as one of the greatest--if not
actually the greatest--of the investigators into this subject before
the age of steam.
The conclusion, that ‘the motive force in birds’ wings is apparently
ten thousand times greater than the resistance of their weight,’
is erroneous, of course, but study of the translation from which
the foregoing excerpt is taken will show that the error detracts
very little from the value of the work itself. Borelli sets out
very definitely the mechanism of flight, in such fashion that he
who runs may read. His reference to ‘the use of a large vessel,’
etc., concerns the suggestion made by Francesco Lana, who antedated
Borelli’s publication of _De Motu Animalium_ by some ten years with his
suggestion for an ‘aerial ship,’ as he called it. Lana’s mind shows, as
regards flight, a more imaginative twist; Borelli dived down into first
causes, and reached mathematical conclusions; Lana conceived a theory
and upheld it--theoretically, since the manner of his life precluded
experiment.
Francesco Lana, son of a noble family, was born in 1631; in 1647 he was
received as a novice into the Society of Jesus at Rome, and remained
a pious member of the Jesuit society until the end of his life. He
was greatly handicapped in his scientific investigations by the vows
of poverty which the rules of the Order imposed on him. He was more
scientist than priest all his life; for two years he held the post of
Professor of Mathematics at Ferrara, and up to the time of his death,
in 1687, he spent by far the greater part of his time in scientific
research. He had the dubious advantage of living in an age when one
man could cover the whole range of science, and this he seems to have
done very thoroughly. There survives an immense work of his entitled,
_Magisterium Naturæ et Artis_, which embraces the whole field of
scientific knowledge as that was developed in the period in which Lana
lived. In an earlier work of his, published in Brescia in 1670, appears
his famous treatise on the aerial ship, a problem which Lana worked out
with thoroughness. He was unable to make practical experiments, and
thus failed to perceive the one insuperable drawback to his project--of
which more anon.
Only extracts from the translation of Lana’s work can be given here,
but sufficient can be given to show fully the means by which he
designed to achieve the conquest of the air. He begins by mention of
the celebrated pigeon of Archytas the Philosopher, and advances one
or two theories with regard to the way in which this mechanical bird
was constructed, and then he recites, apparently with full belief in
it, the fable of _Regiomontanus_ and the eagle that he is said to have
constructed to accompany Charles V. on his entry into Nuremberg. In
fact, Lana starts his work with a study of the pioneers of mechanical
flying up to his own time, and then outlines his own devices for the
construction of mechanical birds before proceeding to detail the
construction of the aerial ship. Concerning primary experiments for
this he says:--
‘I will, first of all, presuppose that air has weight owing to the
vapours and halations which ascend from the earth and seas to a height
of many miles and surround the whole of our terraqueous globe; and this
fact will not be denied by philosophers, even by those who may have
but a superficial knowledge, because it can be proven by exhausting,
if not all, at any rate the greater part of, the air contained in a
glass vessel, which, if weighed before and after the air has been
exhausted, will be found materially reduced in weight. Then I found
out how much the air weighed in itself in the following manner. I
procured a large vessel of glass, whose neck could be closed or opened
by means of a tap, and holding it open I warmed it over a fire, so
that the air inside it becoming rarified, the major part was forced
out; then quickly shutting the tap to prevent the re-entry I weighed
it; which done, I plunged its neck in water, resting the whole of the
vessel on the surface of the water, then on opening the tap the water
rose in the vessel and filled the greater part of it. I lifted the
neck out of the water, released the water contained in the vessel, and
measured and weighed its quantity and density, by which I inferred that
a certain quantity of air had come out of the vessel equal in bulk to
the quantity of water which had entered to refill the portion abandoned
by the air. I again weighed the vessel, after I had first of all well
dried it free of all moisture, and found it weighed one ounce more
whilst it was full of air than when it was exhausted of the greater
part, so that what it weighed more was a quantity of air equal in
volume to the water which took its place. The water weighed 640 ounces,
so I concluded that the weight of air compared with that of water was
1 to 640--that is to say, as the water which filled the vessel weighed
640 ounces, so the air which filled the same vessel weighed one ounce.’
Having thus detailed the method of exhausting air from a vessel, Lana
goes on to assume that any large vessel can be entirely exhausted
of nearly all the air contained therein. Then he takes Euclid’s
proposition to the effect that the superficial area of globes increases
in the proportion of the square of the diameter, whilst the volume
increases in the proportion of the cube of the same diameter, and he
considers that if one only constructs the globe of thin metal, of
sufficient size, and exhausts the air in the manner that he suggests,
such a globe will be so far lighter than the surrounding atmosphere
that it will not only rise, but will be capable of lifting weights.
Here is Lana’s own way of putting it:--
‘But so that it may be enabled to raise heavier weights and to lift
men in the air, let us take double the quantity of copper, 1,232
square feet, equal to 308 lbs. of copper; with this double quantity of
copper we could construct a vessel of not only double the capacity,
but of four times the capacity of the first, for the reason shown by
my fourth supposition. Consequently the air contained in such a vessel
will be 718 lbs. 4⅔ ounces, so that if the air be drawn out of the
vessel it will be 410 lbs. 4⅔ ounces lighter than the same volume of
air, and, consequently, will be enabled to lift three men, or at least
two, should they weigh more than eight pesi each. It is thus manifest
that the larger the ball or vessel is made, the thicker and more solid
can the sheets of copper be made, because, although the weight will
increase, the capacity of the vessel will increase to a greater extent
and with it the weight of the air therein, so that it will always be
capable to lift a heavier weight. From this it can be easily seen how
it is possible to construct a machine which, fashioned like unto a
ship, will float on the air.’
[Illustration: A suggestion for applying hydrogen gas to Lana’s ‘Aerial
Ship.’ Rome, 1784.]
With four globes of these dimensions Lana proposed to make an aerial
ship of the fashion shown in his quaint illustration. He is careful to
point out a method by which the supporting globes for the aerial ship
may be entirely emptied of air; this is to be done by connecting to
each globe a tube of copper which is ‘at least a length of 47 modern
Roman palmi.’ A small tap is to close this tube at the end nearest the
globe, and then vessel and tube are to be filled with water, after
which the tube is to be immersed in water and the tap opened, allowing
the water to run out of the vessel, while no air enters. The tap is
then closed before the lower end of the tube is removed from the water,
leaving no air at all in the globe or sphere. Propulsion of this
airship was to be accomplished by means of sails, and also by oars.
Lana antedated the modern propeller, and realised that the air would
offer enough resistance to oars or paddle to impart motion to any
vessel floating in it and propelled by these means, although he did
not realise the amount of pressure on the air which would be necessary
to accomplish propulsion. As a matter of fact, he foresaw and provided
against practically all the difficulties that would be encountered in
the working, as well as the making, of the aerial ship, finally coming
up against what his religious training made an insuperable objection.
This, again, is best told in his own words:--
‘Other difficulties I do not foresee that could prevail against this
invention, save one only, which to me seems the greatest of them all,
and that is that God would surely never allow such a machine to be
successful, since it would create many disturbances in the civil and
political governments of mankind.’
He ends by saying that no city would be proof against surprise, while
the aerial ship could set fire to vessels at sea, and destroy houses,
fortresses, and cities by fire balls and bombs. In fact, at the end of
his treatise on the subject, he furnishes a pretty complete _résumé_ of
the activities of German Zeppelins.
As already noted, Lana himself, owing to his vows of poverty, was
unable to do more than put his suggestions on paper, which he did with
a thoroughness that has procured him a place among the really great
pioneers of flying.
It was nearly 200 years before any attempt was made to realise his
project; then, in 1843, M. Marey Monge set out to make the globes and
the ship as Lana detailed them. Monge’s experiments cost him the sum
of 25,000 francs 75 centimes, which he expended purely from love of
scientific investigation. He chose to make his globes of brass, about
.004 in thickness, and weighing 1.465 lbs. to the square yard. Having
made his sphere of this metal, he lined it with two thicknesses of
tissue paper, varnished it with oil, and set to work to empty it of
air. This, however, he never achieved, for such metal is incapable of
sustaining the pressure of the outside air, as Lana, had he had the
means to carry out experiments, would have ascertained. M. Monge’s
sphere could never be emptied of air sufficiently to rise from the
earth; it ended in the melting-pot, ignominiously enough, and all that
Monge got from his experiment was the value of the scrap metal and the
satisfaction of knowing that Lana’s theory could never be translated
into practice.
Robert Hooke is less conspicuous than either Borelli or Lana; his
work, which came into the middle of the seventeenth century, consisted
of various experiments with regard to flight, from which emerged ‘a
Module, which by the help of Springs and Wings, raised and sustained
itself in the air.’ This must be reckoned as the first model flying
machine which actually flew, except for da Vinci’s helicopters; Hooke’s
model appears to have been of the flapping-wing type--he attempted to
copy the motion of birds, but found from study and experiment that
human muscles were not sufficient to the task of lifting the human
body. For that reason, he says, ‘I applied my mind to contrive a way
to make artificial muscles,’ but in this he was, as he expresses it,
‘frustrated of my expectations.’ Hooke’s claim to fame rests mainly on
his successful model; the rest of his work is of too scrappy a nature
to rank as a serious contribution to the study of flight.
Contemporary with Hooke was one Allard, who, in France, undertook to
emulate the Saracen of Constantinople to a certain extent. Allard was a
tight-rope dancer who either did or was said to have done short gliding
flights--the matter is open to question--and finally stated that he
would, at St Germains, fly from the terrace in the king’s presence. He
made the attempt, but merely fell, as did the Saracen some centuries
before, causing himself serious injury. Allard cannot be regarded as a
contributor to the development of aeronautics in any way, and is only
mentioned as typical of the way in which, up to the time of the Wright
brothers, flying was regarded. Even unto this day there are many who
still believe that, with a pair of wings, man ought to be able to fly,
and that the mathematical data necessary to effective construction
simply do not exist. This attitude was reasonable enough in an
unlearned age, and Allard was one--a little more conspicuous than the
majority--among many who made experiment in ignorance, with more or
less danger to themselves and without practical result of any kind.
[Illustration: Besnier’s Flying Apparatus.]
The seventeenth century was not to end, however, without practical
experiment of a noteworthy kind in gliding flight. Among the recruits
to the ranks of pioneers was a certain Besnier, a locksmith of Sablé,
who somewhere between 1675 and 1680 constructed a glider of which a
crude picture has come down to modern times. The apparatus, as will
be seen, consisted of two rods with hinged flaps, and the original
designer of the picture seems to have had but a small space in which to
draw, since obviously the flaps must have been much larger than those
shown. Besnier placed the rods on his shoulders, and worked the flaps
by cords attached to his hands and feet--the flaps opened as they fell,
and closed as they rose, so the device as a whole must be regarded as
a sort of flapping glider. Having by experiment proved his apparatus
successful, Besnier promptly sold it to a travelling showman of the
period, and forthwith set about constructing a second set, with which
he made gliding flights of considerable height and distance. Like
Lilienthal, Besnier projected himself into space from some height, and
then, according to the contemporary records, he was able to cross a
river of considerable size before coming to earth. It does not appear
that he had any imitators, or that any advantage whatever was taken
of his experiments; the age was one in which he would be regarded
rather as a freak exhibitor than as a serious student, and possibly,
considering his origin and the sale of his first apparatus to such a
client, he regarded the matter himself as more in the nature of an
amusement than as a discovery.
Borelli, coming at the end of the century, proved to his own
satisfaction and that of his fellows that flapping wing flight was an
impossibility; the capabilities of the plane were as yet undreamed, and
the prime mover that should make the plane available for flight was
deep in the womb of time. Da Vinci’s work was forgotten--flight was an
impossibility, or at best such a useless show as Besnier was able to
give.
The eighteenth century was almost barren of experiment. Emanuel
Swedenborg, having invented a new religion, set about inventing a
flying machine, and succeeded theoretically, publishing the result of
his investigations as follows:--
‘Let a car or boat or some like object be made of light material such
as cork or bark, with a room within it for the operator. Secondly, in
front as well as behind, or all round, set a widely-stretched sail
parallel to the machine, forming within a hollow or bend, which could
be reefed like the sails of a ship. Thirdly, place wings on the sides,
to be worked up and down by a spiral spring, these wings also to be
hollow below in order to increase the force and velocity, take in
the air, and make the resistance as great as may be required. These,
too, should be of light material and of sufficient size; they should
be in the shape of birds’ wings, or the sails of a windmill, or some
such shape, and should be tilted obliquely upwards, and made so as to
collapse on the upward stroke and expand on the downward. Fourth, place
a balance or beam below, hanging down perpendicularly for some distance
with a small weight attached to its end, pendent exactly in line with
the centre of gravity; the longer this beam is, the lighter must it
be, for it must have the same proportion as the well-known vectis or
steel-yard. This would serve to restore the balance of the machine if
it should lean over to any of the four sides. Fifthly, the wings would
perhaps have greater force, so as to increase the resistance and make
the flight easier, if a hood or shield were placed over them, as is
the case with certain insects. Sixthly, when the sails are expanded
so as to occupy a great surface and much air, with a balance keeping
them horizontal, only a small force would be needed to move the machine
back and forth in a circle, and up and down. And, after it has gained
momentum to move slowly upwards, a slight movement and an even bearing
would keep it balanced in the air and would determine its direction at
will.’
The only point in this worthy of any note is the first device for
maintaining stability automatically--Swedenborg certainly scored a
point there. For the rest, his theory was but theory, incapable of
being put to practice--he does not appear to have made any attempt at
advance beyond the mere suggestion.
Some ten years before his time the state of knowledge with regard to
flying in Europe was demonstrated by an order granted by the King of
Portugal to Friar Lourenzo de Guzman, who claimed to have invented a
flying machine capable of actual flight. The order stated that ‘In
order to encourage the suppliant to apply himself with zeal toward
the improvement of the new machine, which is capable of producing the
effects mentioned by him, I grant unto him the first vacant place in
my College of Barcelos or Santarem, and the first professorship of
mathematics in my University of Coimbra, with the annual pension of
600,000 reis during his life.--Lisbon, 17th of March, 1709.’
What happened to Guzman when the non-existence of the machine was
discovered is one of the things that is well outside the province of
aeronautics. He was charlatan pure and simple, as far as actual flight
was concerned, though he had some ideas respecting the design of
hot-air balloons, according to Tissandier. (_La Navigation Aerienne._)
His flying machine was to contain, among other devices, bellows to
produce artificial wind when the real article failed, and also magnets
in globes to draw the vessel in an upward direction and maintain its
buoyancy. Some draughtsman, apparently gifted with as vivid imagination
as Guzman himself, has given to the world an illustration of the
hypothetical vessel; it bears some resemblance to Lana’s aerial ship,
from which fact one draws obvious conclusions.
A rather amusing claim to solving the problem of flight was made in
the middle of the eighteenth century by one Grimaldi, a ‘famous
and unique Engineer’ who, as a matter of actual fact, spent twenty
years in missionary work in India, and employed the spare time that
missionary work left him in bringing his invention to a workable state.
The invention is described as a ‘box which with the aid of clockwork
rises in the air, and goes with such lightness and strong rapidity
that it succeeds in flying a journey of seven leagues in an hour. It
is made in the fashion of a bird; the wings from end to end are 25
feet in extent. The body is composed of cork, artistically joined
together and well fastened with metal wire, covered with parchment
and feathers. The wings are made of catgut and whalebone, and covered
also with the same parchment and feathers, and each wing is folded
in three seams. In the body of the machine are contained thirty
wheels of unique work, with two brass globes and little chains which
alternately wind up a counterpoise; with the aid of six brass vases,
full of a certain quantity of quicksilver, which run in some pulleys,
the machine is kept by the artist in due equilibrium and balance. By
means, then, of the friction between a steel wheel adequately tempered
and a very heavy and surprising piece of lodestone, the whole is kept
in a regulated forward movement, given, however, a right state of the
winds, since the machine cannot fly so much in totally calm weather as
in stormy. This prodigious machine is directed and guided by a tail
seven palmi long, which is attached to the knees and ankles of the
inventor by leather straps; by stretching out his legs, either to the
right or to the left, he moves the machine in whichever direction he
pleases.... The machine’s flight lasts only three hours, after which
the wings gradually close themselves, when the inventor, perceiving
this, goes down gently, so as to get on his own feet, and then winds
up the clockwork and gets himself ready again upon the wings for the
continuation of a new flight. He himself told us that if by chance one
of the wheels came off or if one of the wings broke, it is certain he
would inevitably fall rapidly to the ground, and, therefore, he does
not rise more than the height of a tree or two, as also he only once
put himself in the risk of crossing the sea, and that was from Calais
to Dover, and the same morning he arrived in London.’
And yet there are still quite a number of people who persist in stating
that Bleriot was the first man to fly across the Channel!
A study of the development of the helicopter principle was published
in France in 1868, when the great French engineer Paucton produced his
_Théorie de la Vis d’Archiméde_. For some inexplicable reason, Paucton
was not satisfied with the term ‘helicopter,’ but preferred to call it
a ‘ptérophore,’ a name which, so far as can be ascertained, has not
been adopted by any other writer or investigator. Paucton stated that,
since a man is capable of sufficient force to overcome the weight of
his own body, it is only necessary to give him a machine which acts on
the air ‘with all the force of which it is capable and at its utmost
speed,’ and he will then be able to lift himself in the air, just as
by the exertion of all his strength he is able to lift himself in
water. ‘It would seem,’ says Paucton, ‘that in the ptérophore, attached
vertically to a carriage, the whole built lightly and carefully
assembled, he has found something that will give him this result in all
perfection. In construction, one would be careful that the machine
produced the least friction possible, and naturally it ought to produce
little, as it would not be at all complicated. The new Dædalus, sitting
comfortably in his carriage, would by means of a crank give to the
ptérophore a suitable circular (or revolving) speed. This single
ptérophore would lift him vertically, but in order to move horizontally
he should be supplied with a tail in the shape of another ptérophore.
When he wished to stop for a little time, valves fixed firmly across
the end of the space between the blades would automatically close the
openings through which the air flows, and change the ptérophore into an
unbroken surface which would resist the flow of air and retard the fall
of the machine to a considerable degree.’
The doctrine thus set forth might appear plausible, but it is based
on the common misconception that all the force which might be put
into the helicopter or ‘ptérophore’ would be utilised for lifting
or propelling the vehicle through the air, just as a propeller uses
all its power to drive a ship through water. But, in applying such
a propelling force to the air, most of the force is utilised in
maintaining aerodynamic support--as a matter of fact, more force is
needed to maintain this support than the muscle of man could possibly
furnish to a lifting screw, and even if the helicopter were applied
to a full-sized, engine-driven air vehicle, the rate of ascent would
depend on the amount of surplus power that could be carried. For
example, an upward lift of 1,000 pounds from a propeller 15 feet in
diameter would demand an expenditure of 50 horse-power under the best
possible conditions, and in order to lift this load vertically through
such atmospheric pressure as exists at sea-level or thereabouts, an
additional 20 horse-power would be required to attain a rate of 11
feet per second--50 horse-power must be continually provided for the
mere support of the load, and the additional 20 horse-power must be
continually provided in order to lift it. Although, in model form,
there is nothing quite so strikingly successful as the helicopter in
the range of flying machines, yet the essential weight increases so
disproportionately to the effective area that it is necessary to go but
very little beyond model dimensions for the helicopter to become quite
ineffective.
That is not to say that the lifting screw must be totally ruled out
so far as the construction of aircraft is concerned. Much is still
empirical, so far as this branch of aeronautics is concerned, and
consideration of the structural features of a propeller goes to show
that the relations of essential weight and effective area do not
altogether apply in practice as they stand in theory. Paucton’s dream,
in some modified form, may yet become reality--it is only so short
a time ago as 1896 that Lord Kelvin stated he had not the smallest
molecule of faith in aerial navigation, and since the whole history of
flight consists in proving the impossible possible, the helicopter may
yet challenge the propelled plane surface for aerial supremacy.
It does not appear that Paucton went beyond theory, nor is there in
his theory any advance toward practical flight--da Vinci could have
told him as much as he knew. He was followed by Meerwein, who invented
an apparatus apparently something between a flapping wing machine
and a glider, consisting of two wings, which were to be operated by
means of a rod; the venturesome one who would fly by means of this
apparatus had to lie in a horizontal position beneath the wings to work
the rod. Meerwein deserves a place of mention, however, by reason of
his investigations into the amount of surface necessary to support a
given weight. Taking that weight at 200 pounds--which would allow for
the weight of a man and a very light apparatus--he estimated that 126
square feet would be necessary for support. His pamphlet, published
at Basle in 1784, shows him to have been a painstaking student of the
potentialities of flight.
Jean-Pierre Blanchard, later to acquire fame in connection with
balloon flight, conceived and described a curious vehicle, of which
he even announced trials as impending. His trials were postponed time
after time, and it appears that he became convinced in the end of
the futility of his device, being assisted to such a conclusion by
Lalande, the astronomer, who repeated Borelli’s statement that it was
impossible for man ever to fly by his own strength. This was in the
closing days of the French monarchy, and the ascent of the Mongolfiers’
first hot-air balloon in 1783--which shall be told more fully in its
place--put an end to all French experiments with heavier-than-air
apparatus, though in England the genius of Cayley was about to bud, and
even in France there were those who understood that ballooning was not
true flight.
III
SIR GEORGE CAYLEY--THOMAS WALKER
On the fifth of June, 1783, the Montgolfiers’ hot-air balloon rose
at Versailles, and in its rising divided the study of the conquest
of the air into two definite parts, the one being concerned with the
propulsion of gas lifted, lighter-than-air vehicles, and the other
being crystallised in one sentence by Sir George Cayley: ‘The whole
problem,’ he stated, ‘is confined within these limits, viz.: to make
a surface support a given weight by the application of power to the
resistance of the air.’ For about ten years the balloon held the field
entirely, being regarded as the only solution of the problem of flight
that man could ever compass. So definite for a time was this view on
the eastern side of the Channel that for some years practically all the
progress that was made in the development of power-driven planes was
made in Britain.
In 1800 a certain Dr Thomas Young demonstrated that certain curved
surfaces suspended by a thread moved into and not away from a
horizontal current of air, but the demonstration, which approaches
perilously near to perpetual motion if the current be truly horizontal,
has never been successfully repeated, so that there is more than a
suspicion that Young’s air-current was _not_ horizontal. Others had
made and were making experiments on the resistance offered to the air
by flat surfaces, when Cayley came to study and record, earning such
a place among the pioneers as to win the title of ‘father of British
aeronautics.’
Cayley was a man in advance of his time, in many ways. Of independent
means, he made the grand tour which was considered necessary to the
education of every young man of position, and during this excursion
he was more engaged in studies of a semi-scientific character than in
the pursuits that normally filled such a period. His various writings
prove that throughout his life aeronautics was the foremost subject
in his mind; the _Mechanic’s Magazine_, _Nicholson’s Journal_, the
_Philosophical Magazine_, and other periodicals of like nature bear
witness to Cayley’s continued research into the subject of flight.
He approached the subject after the manner of the trained scientist,
analysing the mechanical properties of air under chemical and physical
action. Then he set to work to ascertain the power necessary for aerial
flight, and was one of the first to enunciate the fallacy of the hopes
of successful flight by means of the steam engine of those days, owing
to the fact that it was impossible to obtain a given power with a given
weight.
Yet his conclusions on this point were not altogether negative, for as
early as 1810 he stated that he could construct a balloon which could
travel with passengers at 20 miles an hour--he was one of the first
to consider the possibilities of applying power to a balloon. Nearly
thirty years later--in 1837--he made the first attempt at establishing
an aeronautical society, but at that time the power-driven plane was
regarded by the great majority as an absurd dream of more or less
mad inventors, while ballooning ranked on about the same level as
tight-rope walking, being considered an adjunct to fairs and fêtes,
more a pastime than a study.
Up to the time of his death, in 1857, Cayley maintained his study of
aeronautical matters, and there is no doubt whatever that his work
went far in assisting the solution of the problem of air conquest. His
principal published work, a monograph entitled _Aerial Navigation_, has
been republished in the admirable series of ‘Aeronautical Classics’
issued by the Royal Aeronautical Society. He began this work by
pointing out the impossibility of flying by means of attached wrings,
an impossibility due to the fact that, while the pectoral muscles of a
bird account for more than two-thirds of its whole muscular strength,
in a man the muscles available for flying, no matter what mechanism
might be used, would not exceed one-tenth of his total strength.
Cayley did not actually deny the possibility of a man flying by
muscular effort, however, but stated that ‘the flight of a strong
man by great muscular exertion, though a curious and interesting
circumstance, inasmuch as it will probably be the means of ascertaining
this power and supplying the basis whereon to improve it, would be of
little use.’
From this he goes on to the possibility of using a Boulton and Watt
steam engine to develop the power necessary for flight, and in this
he saw a possibility of practical result. It is worthy of note that
in this connection he made mention of the forerunner of the modern
internal combustion engine; ‘The French,’ he said, ‘have lately shown
the great power produced by igniting inflammable powders in closed
vessels, and several years ago an engine was made to work in this
country in a similar manner by inflammation of spirit of tar.’ In a
subsequent paragraph of his monograph he anticipates almost exactly the
construction of the Lenoir gas engine, which came into being more than
fifty-five years after his monograph was published.
Certain experiments detailed in his work were made to ascertain the
size of the surface necessary for the support of any given weight.
He accepted a truism of to-day in pointing out that in any matters
connected with aerial investigation, theory and practice are as
widely apart as the poles. Inclined at first to favour the helicopter
principle, he finally rejected this in favour of the plane, with
which he made numerous experiments. During these, he ascertained the
peculiar advantages of curved surfaces, and saw the necessity of
providing both vertical and horizontal rudders in order to admit of
side steering as well as the control of ascent and descent, and for
preserving equilibrium. He may be said to have anticipated the work of
Lilienthal and Pilcher, since he constructed and experimented with a
fixed surface glider. ‘It was beautiful,’ he wrote concerning this, ‘to
see this noble white bird sailing majestically from the top of a hill
to any given point of the plain below it with perfect steadiness and
safety, according to the set of its rudder, merely by its own weight,
descending at an angle of about eight degrees with the horizon.’
[Illustration: Sir George Caley, Bart.
‘The Father of British Aeronautics.’]
It is said that he once persuaded his gardener to trust himself in this
glider for a flight, but if Cayley himself ventured a flight in it he
has left no record of the fact. The following extract from his work,
_Aerial Navigation_, affords an instance of the thoroughness of his
investigations, and the concluding paragraph also shows his faith in
the ultimate triumph of mankind in the matter of aerial flight:--
‘The act of flying requires less exertion than from the appearance is
supposed. Not having sufficient data to ascertain the exact degree of
propelling power exerted by birds in the act of flying, it is uncertain
what degree of energy may be required in this respect for vessels of
aerial navigation; yet when we consider the many hundreds of miles of
continued flight exerted by birds of passage, the idea of its being
only a small effort is greatly corroborated. To apply the power of
the first mover to the greatest advantage in producing this effect is
a very material point. The mode universally adopted by Nature is the
oblique waft of the wing. We have only to choose between the direct
beat overtaking the velocity of the current, like the oar of a boat, or
one applied like the wing, in some assigned degree of obliquity to it.
Suppose 35 feet per second to be the velocity of an aerial vehicle, the
oar must be moved with this speed previous to its being able to receive
any resistance; then if it be only required to obtain a pressure of
one-tenth of a lb. upon each square foot it must exceed the velocity
of the current 7.3 feet per second. Hence its whole velocity must be
42.5 feet per second. Should the same surface be wafted downward like a
wing with the hinder edge inclined upward in an angle of about 50 deg.
40 feet to the current it will overtake it at a velocity of 3.5 feet
per second; and as a slight unknown angle of resistance generates a lb.
pressure per square foot at this velocity, probably a waft of a little
more than 4 feet per second would produce this effect, one-tenth part
of which would be the propelling power. The advantage of this mode of
application compared with the former is rather more than ten to one.
‘In continuing the general principles of aerial navigation, for the
practice of the art, many mechanical difficulties present themselves
which require a considerable course of skilfully applied experiments
before they can be overcome; but, to a certain extent, the air has
already been made navigable, and no one who has seen the steadiness
with which weights to the amount of ten stone (including four stone,
the weight of the machine) hover in the air can doubt of the ultimate
accomplishment of this object.’
This extract from his work gives but a faint idea of the amount of
research for which Cayley was responsible. He had the humility of the
true investigator in scientific problems, and so far as can be seen
was never guilty of the great fault of so many investigators in this
subject--that of making claims which he could not support. He was
content to do, and pass after having recorded his part, and although
nearly half a century had to pass between the time of his death and the
first actual flight by means of power-driven planes, yet he may be said
to have contributed very largely to the solution of the problem, and
his name will always rank high in the roll of the pioneers of flight.
Practically contemporary with Cayley was Thomas Walker, concerning whom
little is known save that he was a portrait painter of Hull, where was
published his pamphlet on _The Art of Flying_ in 1810, a second and
amplified edition being produced, also in Hull, in 1831. The pamphlet,
which has been reproduced _in extenso_ in the _Aeronautical Classics_
series published by the Royal Aeronautical Society, displays a curious
mixture of the true scientific spirit and colossal conceit. Walker
appears to have been a man inclined to jump to conclusions, which
carried him up to the edge of discovery and left him vacillating there.
The study of the two editions of his pamphlet side by side shows that
their author made considerable advances in the practicability of
his designs in the 21 intervening years, though the drawings which
accompany the text in both editions fail to show anything really
capable of flight. The great point about Walker’s work as a whole is
its suggestiveness; he did not hesitate to state that the ‘art’ of
flying is as truly mechanical as that of rowing a boat, and he had
some conception of the necessary mechanism, together with an absolute
conviction that he knew all there was to be known. ‘Encouraged by the
public,’ he says, ‘I would not abandon my purpose of making still
further exertions to advance and complete an art, the discovery of the
_true principles_ (the italics are Walker’s own) of which, I trust, I
can with certainty affirm to be my own.’
The pamphlet begins with Walker’s admiration of the mechanism of flight
as displayed by birds. ‘It is now almost twenty years,’ he says, ‘since
I was first led to think, by the study of birds and their means of
flying, that if an artificial machine were formed with wings in exact
imitation of the mechanism of one of those beautiful living machines,
and applied in the very same way upon the air, there could be no doubt
of its being made to fly, for it is an axiom in philosophy that the
same cause will ever produce the same effect.’ With this he confesses
his inability to produce the said effect through lack of funds, though
he clothes this delicately in the phrase ‘professional avocations and
other circumstances.’ Owing to this inability he published his designs
that others might take advantage of them, prefacing his own researches
with a list of the very early pioneers, and giving special mention to
Friar Bacon, Bishop Wilkins, and the Portuguese friar, De Guzman. But,
although he seems to suggest that others should avail themselves of
his theoretical knowledge, there is a curious incompleteness about the
designs accompanying his work, and about the work itself, which seems
to suggest that he had more knowledge to impart than he chose to make
public--or else that he came very near to complete solution of the
problem of flight, and stayed on the threshold without knowing it.
After a dissertation upon the history and strength of the condor,
and on the differences between the weights of birds, he says: ‘The
following observations upon the wonderful difference in the weight of
some birds, with their apparent means of supporting it in their flight,
may tend to remove some prejudices against my plan from the minds of
some of my readers. The weight of the humming-bird is one drachm, that
of the condor not less than four stone. Now, if we reduce four stone
into drachms we shall find the condor is 14,336 times as heavy as the
humming-bird. What an amazing disproportion of weight! Yet by the
same mechanical use of its wings the condor can overcome the specific
gravity of its body with as much ease as the little humming-bird. But
this is not all. We are informed that this enormous bird possesses a
power in its wings, so far exceeding what is necessary for its own
conveyance through the air, that it can take up and fly away with a
whole sheep in its talons, with as much ease as an eagle would carry
off, in the same manner, a hare or a rabbit. This we may readily
give credit to, from the known fact of our little kestrel and the
sparrowhawk frequently flying off with a partridge, which is nearly
three times the weight of these rapacious little birds.’
After a few more observations he arrives at the following conclusion:
‘By attending to the progressive increase in the weight of birds, from
the delicate little humming-bird up to the huge condor, we clearly
discover that the addition of a few ounces, pounds, or stones, is no
obstacle to the art of flying; the specific weight of birds avails
nothing, for by their possessing wings large enough, and sufficient
power to work them, they can accomplish the means of flying equally
well upon all the various scales and dimensions which we see in nature.
Such being a fact, in the name of reason and philosophy why shall not
man, with a pair of artificial wings, large enough, and with sufficient
power to strike them upon the air, be able to produce the same effect?’
Walker asserted definitely and with good ground that muscular effort
applied without mechanism is insufficient for human flight, but he
states that if an aeronautical boat were constructed so that a man
could sit in it in the same manner as when rowing, such a man would
be able to bring into play his whole bodily strength for the purpose
of flight, and at the same time would be able to get an additional
advantage by exerting his strength upon a lever. At first he concluded
there must be expansion of wings large enough to resist in a sufficient
degree the specific gravity of whatever is attached to them, but in
the second edition of his work he altered this to ‘expansion of flat
passive surfaces large enough to reduce the force of gravity so as
to float the machine upon the air with the man in it.’ The second
requisite is strength enough to strike the wings with sufficient force
to complete the buoyancy and give a projectile motion to the machine.
Given these two requisites, Walker states definitely that flying must
be accomplished simply by muscular exertion. ‘If we are secure of these
two requisites, and I am very confident we are, we may calculate upon
the success of flight with as much certainty as upon our walking.’
Walker appears to have gained some confidence from the experiments
of a certain M. Degen, a watchmaker of Vienna, who, according to the
_Monthly Magazine_ of September, 1809, invented a machine by means of
which a person might raise himself into the air. The said machine,
according to the magazine, was formed of two parachutes which might be
folded up or extended at pleasure, while the person who worked them was
placed in the centre. This account, however, was rather misleading,
for the magazine carefully avoided mention of a balloon to which the
inventor fixed his wings or parachutes. Walker, knowing nothing of
the balloon, concluded that Degen actually raised himself in the air,
though he is doubtful of the assertion that Degen managed to fly in
various directions, especially against the wind.
Walker, after considering Degen and all his works, proceeds to detail
his own directions for the construction of a flying machine, these
being as follows: ‘Make a car of as light material as possible, but
with sufficient strength to support a man in it; provide a pair of
wings about four feet each in length; let them be horizontally expanded
and fastened upon the top edge of each side of the car, with two
joints each, so as to admit of a vertical motion to the wings, which
motion may be effected by a man sitting and working an upright lever in
the middle of the car. Extend in the front of the car a flat surface of
silk, which must be stretched out and kept fixed in a passive state;
there must be the same fixed behind the car; these two surfaces must
be perfectly equal in length and breadth and large enough to cover a
sufficient quantity of air to support the whole weight as nearly in
equilibrium as possible, thus we shall have a great sustaining power
in those passive surfaces and the active wings will propel the car
forward.’
A description of how to launch this car is subsequently given: ‘It
becomes necessary,’ says the theorist, ‘that I should give directions
how it may be launched upon the air, which may be done by various
means; perhaps the following method may be found to answer as well as
any: Fix a poll upright in the earth, about twenty feet in height,
with two open collars to admit another poll to slide upwards through
them; let there be a sliding platform made fast upon the top of the
sliding poll; place the car with a man in it upon the platform, then
raise the platform to the height of about thirty feet by means of the
sliding poll, let the sliding poll and platform suddenly fall down,
the car will then be left upon the air, and by its pressing the air
a projectile force will instantly propel the car forward; the man in
the car must then strike the active wings briskly upon the air, which
will so increase the projectile force as to become superior to the
force of gravitation, and if he inclines his weight a little backward,
the projectile impulse will drive the car forward in an ascending
direction. When the car is brought to a sufficient altitude to clear
the tops of hills, trees, buildings, etc., the man, by sitting a little
forward on his seat, will then bring the wings upon a horizontal plane,
and by continuing the action of the wings he will be impelled forward
in that direction. To descend, he must desist from striking the wings,
and hold them on a level with their joints; the car will then gradually
come down, and when it is within five or six feet of the ground the man
must instantly strike the wings downwards, and sit as far back as he
can; he will by this means check the projectile force, and cause the
car to alight very gently with a retrograde motion. The car, when up
in the air, may be made to turn to the right or to the left by forcing
out one of the fins, having one about eighteen inches long placed
vertically on each side of the car for that purpose, or perhaps merely
by the man inclining the weight of his body to one side.’
Having stated how the thing is to be done, Walker is careful to explain
that when it is done there will be in it some practical use, notably
in respect of the conveyance of mails and newspapers, or the saving of
life at sea, or for exploration, etc. It might even reduce the number
of horses kept by man for his use, by means of which a large amount of
land might be set free for the growth of food for human consumption.
At the end of his work Walker admits the idea of steam power for
driving a flying machine in place of simple human exertion, but he,
like Cayley, saw a drawback to this in the weight of the necessary
engine. On the whole, he concluded, navigation of the air by means of
engine power would be mostly confined to the construction of navigable
balloons.
As already noted, Walker’s work is not over practical, and the
foregoing extract includes the most practical part of it; the rest is
a series of dissertations on bird flight, in which, evidently, the
portrait painter’s observations were far less thorough than those
of da Vinci or Borelli. Taken on the whole, Walker was a man with a
hobby; he devoted to it much time and thought, but it remained a hobby,
nevertheless. His observations have proved useful enough to give him a
place among the early students of flight, but a great drawback to his
work is the lack of practical experiment, by means of which alone real
advance could be made; for, as Cayley admitted, theory and practice are
very widely separated in the study of aviation, and the whole history
of flight is a matter of unexpected results arising from scarcely
foreseen causes, together with experiment as patient as daring.
IV
THE MIDDLE NINETEENTH CENTURY
Both Cayley and Walker were theorists, though Cayley supported his
theoretical work with enough of practice to show that he studied
along right lines; a little after his time there came practical men
who brought to being the first machine which actually flew by the
application of power. Before their time, however, mention must be made
of the work of George Pocock of Bristol, who, somewhere about 1840,
invented what was described as a ‘kite carriage,’ a vehicle which
carried a number of persons, and obtained its motive power from a large
kite. It is on record that, in the year 1846, one of these carriages
conveyed sixteen people from Bristol to London. Another device of
Pocock’s was what he called a ‘buoyant sail,’ which was in effect
a man-lifting kite, and by means of which a passenger was actually
raised 100 yards from the ground, while the inventor’s son scaled a
cliff 200 feet in height by means of one of these ‘buoyant sails.’
This constitutes the first definitely recorded experiment in the use
of man-lifting kites. _A History of the Charvolant or Kite-Carriage_,
published in London in 1851, states that ‘an experiment of a bold
and very novel character was made upon an extensive down, where a
large wagon with a considerable load was drawn along, whilst this
huge machine at the same time carried an observer aloft in the air,
realising almost the romance of flying.’
Experimenting, two years after the appearance of the ‘kite-carriage,’
on the helicopter principle, W. H. Phillips constructed a model
machine which weighed two pounds; this was fitted with revolving fans,
driven by the combustion of charcoal, nitre, and gypsum, producing
steam which, discharging into the air, caused the fans to revolve.
The inventor stated that ‘all being arranged, the steam was up in a
few seconds, when the whole apparatus spun around like any top, and
mounted into the air faster than a bird; to what height it ascended
I had no means of ascertaining; the distance travelled was across
two fields, where, after a long search, I found the machine minus
the wings, which had been torn off in contact with the ground.’ This
could hardly be described as successful flight, but it was an advance
in the construction of machines on the helicopter principle, and it
was the first steam-driven model of the type which actually flew. The
invention, however, was not followed up.
After Phillips, we come to the great figures of the middle nineteenth
century, W. S. Henson and John Stringfellow. Cayley had shown, in 1809,
how success might be attained by developing the idea of the plane
surface so driven as to take advantage of the resistance offered by
the air, and Henson, who as early as 1840 was experimenting with model
gliders and light steam engines, evolved and patented an idea for
something very nearly resembling the monoplane of the early twentieth
century. His patent, No. 9478, of the year 1842, explains the principle
of the machine as follows:--
‘In order that the description hereafter given may be rendered clear,
I will first shortly explain the principle on which the machine is
constructed. If any light and flat or nearly flat article be projected
or thrown edgewise in a slightly inclined position, the same will
rise on the air till the force exerted is expended, when the article
so thrown or projected will descend; and it will readily be conceived
that, if the article so projected or thrown possessed in itself a
continuous power or force equal to that used in throwing or projecting
it, the article would continue to ascend so long as the forward part
of the surface was upwards in respect to the hinder part, and that
such article, when the power was stopped, or when the inclination was
reversed, would descend by gravity aided by the force of the power
contained in the article, if the power be continued, thus imitating the
flight of a bird.
[Illustration: Henson’s proposed flying machine.]
[Illustration: Stringfellow’s power-driven model--the first model to
achieve engine-driven flight.]
Now, the first part of my invention consists of an apparatus so
constructed as to offer a very extended surface or plane of a light yet
strong construction, which will have the same relation to the general
machine which the extended wings of a bird have to the body when a
bird is skimming in the air; but in place of the movement or power for
onward progress being obtained by movement of the extended surface
or plane, as is the case with the wings of birds, I apply suitable
paddle-wheels or other proper mechanical propellers worked by a steam
or other sufficiently light engine, and thus obtain the requisite
power for onward movement to the plane or extended surface; and in
order to give control as to the upward and downward direction of such
a machine I apply a tail to the extended surface which is capable of
being inclined or raised, so that when the power is acting to propel
the machine, by inclining the tail upwards, the resistance offered
by the air will cause the machine to rise on the air; and, on the
contrary, when the inclination of the tail is reversed, the machine
will immediately be propelled downwards, and pass through a plane more
or less inclined to the horizon as the inclination of the tail is
greater or less; and in order to guide the machine as to the lateral
direction which it shall take, I apply a vertical rudder or second
tail, and, according as the same is inclined in one direction or the
other, so will be the direction of the machine.’
The machine in question was very large, and differed very little from
the modern monoplane; the materials were to be spars of bamboo and
hollow wood, with diagonal wire bracing. The surface of the planes was
to amount to 4,500 square feet, and the tail, triangular in form (here
modern practice diverges) was to be 1,500 square feet. The inventor
estimated that there would be a sustaining power of half a pound per
square foot, and the driving power was to be supplied by a steam engine
of 25 to 30 horse-power, driving two six-bladed propellers. Henson was
largely dependent on Stringfellow for many details of his design, more
especially with regard to the construction of the engine.
The publication of the patent attracted a great amount of public
attention, and the illustrations in contemporary journals, representing
the machine flying over the pyramids and the Channel, anticipated
fact by sixty years and more; the scientific world was divided, as it
was up to the actual accomplishment of flight, as to the value of the
invention.
Stringfellow and Henson became associated, after the conception of
their design, with an attorney named Colombine, and a Mr Marriott, and
between the four of them a project grew for putting the whole thing on
a commercial basis--Henson and Stringfellow were to supply the idea;
Marriott, knowing a member of Parliament, would be useful in getting a
company incorporated, and Colombine would look after the purely legal
side of the business. Thus an application was made by Mr Roebuck,
Marriott’s M.P., for an act of incorporation for ‘The Aerial Steam
Transit Company,’ Roebuck moving to bring in the bill on the 24th of
March, 1843. The prospectus, calling for funds for the development of
the invention, makes interesting reading at this stage of aeronautical
development; it was as follows:--
PROPOSAL.
For subscriptions of sums of £100, in furtherance of an
Extraordinary Invention not at present safe to be developed by
securing the necessary Patents, for which three times the sum
advanced, namely, £300, is conditionally guaranteed for each
subscription on February 1, 1844, in case of the anticipations
being realised, with the option of the subscribers being
shareholders for the large amount if so desired, but not otherwise.
* * * * *
An Invention has recently been discovered, which if ultimately
successful will be without parallel even in the age which
introduced to the world the wonderful effects of gas and of steam.
The discovery is of that peculiar nature, so simple in principle
yet so perfect in all the ingredients required for complete and
permanent success, that to promulgate it at present would wholly
defeat its development by the immense competition which would
ensue, and the views of the originator be entirely frustrated.
This work, the result of years of labour and study, presents a
wonderful instance of the adaptation of laws long since proved
to the scientific world combined with established principles so
judiciously and carefully arranged, as to produce a discovery
perfect in all its parts and alike in harmony with the laws of
Nature and of science.
The Invention has been subjected to several tests and examinations
and the results are most satisfactory, so much so that nothing
but the completion of the undertaking is required to determine
its practical operation, which being once established its utility
is undoubted, as it would be a necessary possession of every
empire, and it were hardly too much to say, of every individual of
competent means in the civilised world.
Its qualities and capabilities are so vast that it were impossible
and, even if possible, unsafe to develop them further, but some
idea may be formed from the fact that as a preliminary measure
patents in Great Britain, Ireland, Scotland, the Colonies, France,
Belgium, and the United States, and every other country where
protection to the first discoveries of an Invention is granted,
will of necessity be immediately obtained, and by the time these
are perfected, which it is estimated will be in the month of
February, the Invention will be fit for Public Trial, but until the
Patents are sealed any further disclosure would be most dangerous
to the principle on which it is based.
Under these circumstances, it is proposed to raise an immediate
sum of £2,000 in furtherance of the Projector’s views, and as
some protection to the parties who may embark in the matter, that
this is not a visionary plan for objects imperfectly considered,
Mr Colombine, to whom the secret has been confided, has allowed
his name to be used on the occasion, and who will if referred
to corroborate this statement, and convince any inquirer of the
reasonable prospects of large pecuniary results following the
development of the Invention.
It is, therefore, intended to raise the sum of £2,000 in twenty
sums of £100 each (of which any subscriber may take one or more not
exceeding five in number to be held by any individual) the amount
of which is to be paid into the hands of Mr Colombine as General
Manager of the concern to be by him appropriated in procuring the
several Patents and providing the expenses incidental to the works
in progress. For each of which sums of £100 it is intended and
agreed that twelve months after the 1st February next, the several
parties subscribing shall receive as an equivalent for the risk to
be run the sum of £300 for each of the sums of £100 now subscribed,
provided when the time arrives the Patents shall be found to answer
the purposes intended.
As full and complete success is alone looked to, no moderate or
imperfect benefit is to be anticipated, but the work, if it once
passes the necessary ordeal, to which inventions of every kind
must be first subject, will then be regarded by every one as the
most astonishing discovery of modern times; no half success can
follow, and therefore the full nature of the risk is immediately
ascertained.
The intention is to work and prove the Patent by collective instead
of individual aid as less hazardous at first and more advantageous
in the result for the Inventor, as well as others, by having the
interest of several engaged in aiding one common object--the
development of a Great Plan. The failure is not feared, yet as
perfect success might, by possibility, not ensue, it is necessary
to provide for that result, and the parties concerned make it a
condition that no return of the subscribed money shall be required,
if the Patents shall by any unforeseen circumstances not be capable
of being worked at all; against which, the first application of
the money subscribed, that of securing the Patents, affords a
reasonable security, as no one without solid grounds would think of
such an expenditure.
It is perfectly needless to state that no risk or responsibility of
any kind can arise beyond the payment of the sum to be subscribed
under any circumstances whatever.
As soon as the Patents shall be perfected and proved it is
contemplated, so far as may be found practicable, to further the
great object in view a Company shall be formed but respecting which
it is unnecessary to state further details, than that a preference
will be given to all those persons who now subscribe, and to whom
shares shall be appropriated according to the larger amount (being
three times the sum to be paid by each person) contemplated to
be returned as soon as the success of the Invention shall have
been established, at their option, or the money paid, whereby the
Subscriber will have the means of either withdrawing with a large
pecuniary benefit, or by continuing his interest in the concern,
lay the foundation for participating in the immense benefit which
must follow the success of the plan.
It is not pretended to conceal that the project is a
speculation--all parties believe that perfect success, and thence
incalculable advantage of every kind, will follow to every
individual joining in this great undertaking; but the Gentlemen
engaged in it wish that no concealment of the consequences, perfect
success, or possible failure, should in the slightest degree
be inferred. They believe this will prove the germ of a mighty
work, and in that belief call for the operation of others with no
visionary object, but a legitimate one before them, to attain that
point where perfect success will be secured from their combined
exertions.
All applications to be made to D. E. Colombine, Esquire, 8 Carlton
Chambers, Regent Street.
The applications did not materialise, as was only to be expected in
view of the vagueness of the proposals. Colombine did some advertising,
and Mr Roebuck expressed himself as unwilling to proceed further in the
venture. Henson experimented with models to a certain extent, while
Stringfellow looked for funds for the construction of a full-sized
monoplane. In November of 1843 he suggested that he and Henson should
construct a large model out of their own funds. On Henson’s suggestion
Colombine and Marriott were bought out as regards the original patent,
and Stringfellow and Henson entered into an agreement and set to work.
Their work is briefly described in a little pamphlet by F. J.
Stringfellow, entitled _A few Remarks on what has been done with
screw-propelled Aeroplane Machines from 1809 to 1892_. The author
writes with regard to the work that his father and Henson undertook:--
‘They commenced the construction of a small model operated by a spring,
and laid down the larger model 20 ft. from tip to tip of planes, 3½ ft.
wide, giving 70 ft. of sustaining surface, about 10 more in the tail.
The making of this model required great consideration; various supports
for the wings were tried, so as to combine lightness with firmness,
strength and rigidity.
‘The planes were staid from three sets of fish-shaped masts, and rigged
square and firm by flat steel rigging. The engine and boiler were
put in the car to drive two screw-propellers, right and left-handed,
3 ft. in diameter, with four blades each, occupying three-quarters
of the area of the circumference, set at an angle of 60 degrees. A
considerable time was spent in perfecting the motive power. Compressed
air was tried and abandoned. Tappets, cams, and eccentrics were all
tried, to work the slide valve, to obtain the best results. The piston
rod of engine passed through both ends of the cylinder, and with long
connecting rods worked direct on the crank of the propellers. From
memorandum of experiments still preserved the following is a copy of
one: June, 27th, 1845, water 50 ozs., spirit 10 ozs., lamp lit 8.45,
gauge moves 8.46, engine started 8.48 (100 lb. pressure), engine
stopped 8.57, worked 9 minutes, 2,288 revolutions, average 254 per
minute. No priming, 40 ozs. water consumed, propulsion (thrust of
propellers), 5 lbs. 4½ ozs. at commencement, steady, 4 lbs. ½ oz., 57
revolutions to 1 oz. water, steam cut off one-third from beginning.
‘The diameter of cylinder of engine was 1½ inch, length of stroke 3
inches.
‘In the meantime an engine was also made for the smaller model, and a
wing action tried, but with poor results. The time was mostly devoted
to the larger model, and in 1847 a tent was erected on Bala Down,
about two miles from Chard, and the model taken up one night by the
workmen. The experiments were not so favourable as was expected. The
machine could not support itself for any distance, but, when launched
off, gradually descended, although the power and surface should have
been ample; indeed, according to latest calculations, the thrust should
have carried more than three times the weight, for there was a thrust
of 5 lbs. from the propellers, and a surface of over 70 square feet to
sustain under 30 lbs., but necessary speed was lacking.’
[Illustration: Stringfellow’s model triplane, 1868.]
Stringfellow himself explained the failure as follows:--
‘There stood our aerial protégée in all her purity--too delicate,
too fragile, too beautiful for this rough world; at least those were
my ideas at the time, but little did I think how soon it was to be
realised. I soon found, before I had time to introduce the spark, a
drooping in the wings, a flagging in all the parts. In less than ten
minutes the machine was saturated with wet from a deposit of dew, so
that anything like a trial was impossible by night. I did not consider
we could get the silk tight and rigid enough. Indeed, the framework
altogether was too weak. The steam-engine was the best part. Our
want of success was not for want of power or sustaining surface, but
for want of proper adaptation of the means to the end of the various
parts.’
Henson, who had spent a considerable amount of money in these
experimental constructions, consoled himself for failure by venturing
into matrimony; in 1849 he went to America, leaving Stringfellow to
continue experimenting alone. From 1846 to 1848 Stringfellow worked on
what is really an epoch-making item in the history of aeronautics--the
first engine-driven aeroplane which actually flew. The machine in
question had a 10 foot span, and was 2 ft. across in the widest part
of the wing; the length of tail was 3 ft. 6 ins., and the span of tail
in the widest part 22 ins., the total sustaining area being about 14
sq. ft. The motive power consisted of an engine with a cylinder of
three-quarter inch diameter and a two-inch stroke; between this and
the crank shaft was a bevelled gear giving three revolutions of the
propellers to every stroke of the engine; the propellers, right and
left screw, were four-bladed and 16 inches in diameter. The total
weight of the model with engine was 8 lbs. Its successful flight is
ascribed to the fact that Stringfellow curved the wings, giving them
rigid front edges and flexible trailing edges, as suggested long before
both by Da Vinci and Borelli, but never before put into practice.
Mr F. J. Stringfellow, in the pamphlet quoted above, gives the best
account of the flight of this model: ‘My father had constructed another
small model which was finished early in 1848, and having the loan of
a long room in a disused lace factory, early in June the small model
was moved there for experiments. The room was about 22 yards long and
from 10 to 12 ft. high.... The inclined wire for starting the machine
occupied less than half the length of the room and left space at the
end for the machine to clear the floor. In the first experiment the
tail was set at too high an angle, and the machine rose too rapidly on
leaving the wire. After going a few yards it slid back as if coming
down an inclined plane, at such an angle that the point of the tail
struck the ground and was broken. The tail was repaired and set at a
smaller angle. The steam was again got up, and the machine started
down the wire, and, upon reaching the point of self-detachment, it
gradually rose until it reached the farther end of the room, striking a
hole in the canvas placed to stop it. In experiments the machine flew
well, when rising as much as one in seven. The late Rev. J. Riste,
Esq., lace manufacturer, Northcote Spicer, Esq., J. Toms, Esq., and
others witnessed experiments. Mr Marriatt, late of the San Francisco
_News Letter_ brought down from London Mr Ellis, the then lessee of
Cremorne Gardens, Mr Partridge, and Lieutenant Gale, the aeronaut, to
witness experiments. Mr Ellis offered to construct a covered way at
Cremorne for experiments. Mr Stringfellow repaired to Cremorne, but not
much better accommodations than he had at home were provided, owing
to unfulfilled engagement as to room. Mr Stringfellow was preparing
for departure when a party of gentlemen unconnected with the Gardens
begged to see an experiment, and finding them able to appreciate his
endeavours, he got up steam and started the model down the wire. When
it arrived at the spot where it should leave the wire it appeared to
meet with some obstruction, and threatened to come to the ground, but
it soon recovered itself and darted off in as fair a flight as it was
possible to make at a distance of about 40 yards, where it was stopped
by the canvas.
‘Having now demonstrated the practicability of making a steam-engine
fly, and finding nothing but a pecuniary loss and little honour,
this experimenter rested for a long time, satisfied with what he had
effected. The subject, however, had to him special charms, and he still
contemplated the renewal of his experiments.’
It appears that Stringfellow’s interest did not revive sufficiently
for the continuance of the experiments until the founding of the
Aeronautical Society of Great Britain in 1866. Wenham’s paper on Aerial
Locomotion read at the first meeting of the Society, which was held
at the Society of Arts under the Presidency of the Duke of Argyll,
was the means of bringing Stringfellow back into the field. It was
Wenham’s suggestion, in the first place, that monoplane design should
be abandoned for the superposition of planes; acting on this suggestion
Stringfellow constructed a model triplane, and also designed a steam
engine of slightly over one horse-power, and a one horse-power copper
boiler and fire box which, although capable of sustaining a pressure of
500 lbs. to the square inch, weighed only about 40 lbs.
Both the engine and the triplane model were exhibited at the first
Aeronautical Exhibition held at the Crystal Palace in 1868. The
triplane had a supporting surface of 28 sq. ft.; inclusive of engine,
boiler, fuel, and water its total weight was under 12 lbs. The engine
worked two 21 in. propellers at 600 revolutions per minute, and
developed 100 lbs. steam pressure in five minutes, yielding one-third
horse-power. Since no free flight was allowed in the Exhibition, owing
to danger from fire, the triplane was suspended from a wire in the
nave of the building, and it was noted that, when running along the
wire, the model made a perceptible lift.
A prize of £100 was awarded to the steam engine as the lightest steam
engine in proportion to its power. The engine and model together may
be reckoned as Stringfellow’s best achievement. He used his £100 in
preparation for further experiments, but he was now an old man, and
his work was practically done. Both the triplane and the engine were
eventually bought for the Washington Museum; Stringfellow’s earlier
models, together with those constructed by him in conjunction with
Henson, remain in this country in the Victoria and Albert Museum.
John Stringfellow died on December 13th, 1883. His place in the history
of aeronautics is at least equal to that of Cayley, and it may be
said that he laid the foundation of such work as was subsequently
accomplished by Maxim, Langley, and their fellows. It was the coming
of the internal combustion engine that rendered flight practicable,
and had this prime mover been available in John Stringfellow’s day
the Wright brothers’ achievement might have been antedated by half a
century.
V
WENHAM, LE BRIS, AND SOME OTHERS