For many years after the publication of Sir George Cayley's articles
and lectures on aviation very little was done in the way of aerial
experiments. True, about midway through the nineteenth century two
clever engineers, Henson and Stringfellow, built a model aeroplane after
the design outlined by Sir George; but though their model was not of
much practical value, a little more valuable experience was accumulated
which would be of service when the time should come; in other words,
when the motor engine should arrive. This model can be seen at the
Victoria and Albert Museum, at South Kensington.
A few years later Stringfellow designed a tiny steam-engine, which he
fitted to an equally tiny monoplane, and it is said that by its aid
he was able to obtain a very short flight through the air. As some
recognition of his enterprise the Aeronautical Society, which was
founded in 1866, awarded him a prize of L100 for his engine.
The idea of producing a practical form of flying machine was never
abandoned entirely. Here and there experiments continued to be carried
out, and certain valuable conclusions were arrived at. Many advanced
thinkers and writers of half a century ago set forth their opinions on
the possibilities of human flight. Some of them, like Emerson, not only
believed that flight would come, but also stated why it had not arrived.
Thus Emerson, when writing on the subject of air navigation about fifty
years ago, remarked: "We think the population is not yet quite fit for
them, and therefore there will be none. Our friend suggests so many
inconveniences from piracy out of the high air to orchards and lone
houses, and also to high fliers, and the total inadequacy of the present
system of defence, that we have not the heart to break the sleep of the
great public by the repetition of these details. When children come into
the library we put the inkstand and the watch on the high shelf until
they be a little older."
About the year 1870 a young German engineer, named Otto Lilienthal,
began some experiments with a motorless glider, which in course of time
were to make him world-famed. For nearly twenty years Lilienthal carried
on his aerial research work in secrecy, and it was not until about the
year 1890 that his experimental work was sufficiently advanced for him
to give demonstrations in public.
The young German was a firm believer in what was known as the
"soaring-plane" theory of flight. From the picture here given we can get
some idea of his curious machine. It consisted of large wings, formed of
thin osiers, over which was stretched light fabric. At the back were
two horizontal rudders shaped somewhat like the long forked tail of
a swallow, and over these was a large steering rudder. The wings were
arranged around the glider's body. The whole apparatus weighed about 40
pounds.
Lilienthal's flights, or glides, were made from the top of a
specially-constructed large mound, and in some cases from the summit of
a low tower. The "birdman" would stand on the top of the mound, full
to the wind, and run quickly forward with outstretched wings. When he
thought he had gained sufficient momentum he jumped into the air, and
the wings of the glider bore him through the air to the base of the
mound.
To preserve the balance of his machine--always a most difficult feat--he
swung his legs and hips to one side or the other, as occasion required,
and, after hundreds of glides had been made, he became so skilful in
maintaining the equilibrium of his machine that he was able to cover a
distance, downhill, of 300 yards.
Later on, Lilienthal abandoned the glider, or elementary form of
monoplane, and adopted a system of superposed planes, corresponding
to the modern biplane. The promising career of this clever German was
brought to an untimely end in 1896, when, in attempting to glide from
a height of about 80 yards, his apparatus made a sudden downward swoop,
and he broke his neck.
Now that Lillenthal's experiments had proved conclusively the efficiency
of wings, or planes, as carrying surfaces, other engineers followed in
his footsteps, and tried to improve on his good work.
The first "birdman" to use a glider in this country was Mr. Percy
Pilcher who carried out his experiments at Cardross in Scotland. His
glides were at first made with a form of apparatus very similar to that
employed by Lilienthal, and in time he came to use much larger
machines. So cumbersome, however, was his apparatus--it weighed nearly
4 stones--that with such a great weight upon his shoulders he could not
run forward quickly enough to gain sufficient momentum to "carry off"
from the hillside. To assist him in launching the apparatus the machine
was towed by horses, and when sufficient impetus had been gained the
tow-rope was cast off.
Three years after Lilienthal's death Pilcher met with a similar
accident. While making a flight his glider was overturned, and the
unfortunate "birdman" was dashed to death.
In America there were at this time two or three "human birds", one of
the most famous being M. Octave Chanute. During the years 1895-7 Chanute
made many flights in various types of gliding machines, some of which
had as many as half a dozen planes arranged one above another. His best
results, however, were obtained by the two-plane machine, resembling to
a remarkable extent the modern biplane.