al transport the higher speeds
are more economical of power than the lower ones."

This Mr. Maxim is evidently ready to endorse, stating, in his own words,
that birds obtain the greater part of their support by moving forward
with sufficient velocity so as to be constantly resting on new air, the
inertia of which has not been disturbed. Mr. Maxim's trials were on a
scale comparable with all his mechanical achievements. He employed for
his experiments a rotating arm, sweeping out a circle, the circumference
of which was 200 feet. To the end of this arm he attached a cigar-shaped
apparatus, driven by a screw, and arranged in such a manner that
aero-planes could be attached to it at any angle. These planes were on
a large scale, carrying weights of from 20 lbs. to 100 lbs. With this
contrivance he found that, whatever push the screw communicated to the
aero-plane, "the plane would lift in a vertical direction from ten to
fifteen times as much as the horizontal push that it received from the
screw, and which depended upon the angle at which the plane was set, and
the speed at which the apparatus was travelling through the air." Next,
having determined by experiment the power required to perform artificial
flight, Mr. Maxim applied himself to designing the requisite motor.
"I constructed," he states, "two sets of compound engines of tempered
steel, all the parts being made very light and strong, and a steam
generator of peculiar construction, the greater part of the heating
surface consisting of small and thin copper tubes. For fuel I employed
naphtha."

This Mr. Maxim wrote in 1892, adding that he was then experimenting with
a large machine, having a spread of over 100 feet. Labour, skill, and
money were lavishly devoted henceforward to the great task undertaken,
and it was not long before the giant flying machine, the outcome of so
much patient experimenting, was completed and put to a practical trial.
Its weight was 7,500 lbs. The screw propellers were nearly 18 feet in
diameter, each with two blades, while the engines were capable of being
run up to 360 horse power. The entire machine was mounted on an inner
railway track of 9 feet and an outer of 35 feet gauge, while above there
was a reversed rail along which the machine would begin to run so soon
as with increase of speed it commenced to lift itself off the inner
track.

In one of the latest experiments it was found that when a speed of 42
miles an hour was attaine