staining surface to a pound of weight, whereas he calculated
that a bird could soar with a surface of less than half a foot to the
pound. He next proceeded to steam-driven models in which for a time he
found an insuperable difficulty in keeping down the weight, which, in
practice, always exceeded his calculation; and it was not till the end
of 1893 that he felt himself prepared for a fair trial. At this time he
had prepared a model weighing between nine and ten pounds, and he needed
only a suitable launching apparatus to be used over water. The model
would, like a bird, require an initial velocity imparted to it, and the
discovery of a suitable apparatus gave him great trouble. For the rest
the facilities for launching were supplied by a houseboat moored on the
Potomac. Foiled again and again by many difficulties, it was not till
after repeated failures and the lapse of many months, when, as the
Professor himself puts it, hope was low, that success finally came. It
was in the early part of 1896 that a successful flight was accomplished
in the presence of Dr. Bell, of telephone fame, and the following is
a brief epitome of the account that this accomplished scientist
contributed to the columns of Nature:--

"The flying machine, built, apparently, almost entirely of metal, was
driven by an engine said to weigh, with fuel and water, about 25 lbs.,
the supporting surface from tip to tip being 12 or 14 feet. Starting
from a platform about 20 feet high, the machine rose at first directly
in the face of the wind, moving with great steadiness, and subsequently
wheeling in large curves until steam was exhausted, when, from a height
of 80 or 100 feet, it shortly settled down. The experiment was then
repeated with similar results. Its motion was so steady that a glass of
water might have remained unspilled. The actual length of flight each
time, which lasted for a minute and a half, exceeded half a mile, while
the velocity was between twenty and twenty-five miles an hour in a
course that was constantly taking it 'up hill.' A yet more successful
flight was subsequently made."

But flight of another nature was being courageously attempted at this
time. Otto Lilienthal, of Berlin, in imitation of the motion of birds,
constructed a flying apparatus which he operated himself, and with which
he could float down from considerable elevations. "The feat," he
warns tyros, "requires practice. In the beginning the height should be
moderate,