25 miles
an hour, and nothing less than 500 horse-power could drive it at this
speed. But a boat which could make 40 miles an hour with engines of
1,000 horse-power would still move 4 miles an hour even if the engines
were reduced to 1 horse-power. The problems of land and water travel
were solved in the nineteenth century, because it was possible to begin
with small achievements, and gradually work up to our present success.
The flying problem was left over to the twentieth century, because in
this case the art must be highly developed before any flight of any
considerable duration at all can be obtained.

'However, there is another way of flying which requires no artificial
motor, and many workers believe that success will come first by this
road. I refer to the soaring flight, by which the machine is permanently
sustained in the air by the same means that are employed by soaring
birds. They spread their wings to the wind, and sail by the hour,
with no perceptible exertion beyond that required to balance and steer
themselves. What sustains them is not definitely known, though it is
almost certain that it is a rising current of air. But whether it be a
rising current or something else, it is as well able to support a
flying machine as a bird, if man once learns the art of utilising it.
In gliding experiments it has long been known that the rate of vertical
descent is very much retarded, and the duration of the flight greatly
prolonged, if a strong wind blows UP the face of the hill parallel
to its surface. Our machine, when gliding in still air, has a rate of
vertical descent of nearly 6 feet per second, while in a wind blowing
26 miles per hour up a steep hill we made glides in which the rate of
descent was less than 2 feet per second. And during the larger part of
this time, while the machine remained exactly in the rising current,
THERE WAS NO DESCENT AT ALL, BUT EVEN A SLIGHT RISE. If the operator
had had sufficient skill to keep himself from passing beyond the rising
current he would have been sustained indefinitely at a higher point than
that from which he started. The illustration shows one of these very
slow glides at a time when the machine was practically at a standstill.
The failure to advance more rapidly caused the photographer some trouble
in aiming, as you will perceive. In looking at this picture you will
readily understand that the excitement of gliding experiments does
not entirely cease with the bre