undulations of its surface, or he
could cause it to sail out almost on a level with the starting point,
and, passing high above the foot of the hill, gradually settle down to
the ground. The wind on this day was blowing eleven to fourteen miles
per hour. The next day, the conditions being favourable, the machine
was again taken out for trial. This time the velocity of the wind was
eighteen to twenty-two miles per hour. At first we felt some doubt as to
the safety of attempting free flight in so strong a wind, with a machine
of over 300 square feet and a practice of less than five minutes spent
in actual flight. But after several preliminary experiments we decided
to try a glide. The control of the machine seemed so good that we then
felt no apprehension in sailing boldly forth. And thereafter we made
glide after glide, sometimes following the ground closely and sometimes
sailing high in the air. Mr Chanute had his camera with him and took
pictures of some of these glides, several of which are among those
shown.

'We made glides on subsequent days, whenever the conditions were
favourable. The highest wind thus experimented in was a little over
twelve metres per second--nearly twenty-seven miles per hour.

It had been our intention when building the machine to do the larger
part of the experimenting in the following manner:--When the wind blew
seventeen miles an hour, or more, we would attach a rope to the machine
and let it rise as a kite with the operator upon it. When it should
reach a proper height the operator would cast off the rope and glide
down to the ground just as from the top of a hill. In this way we would
be saved the trouble of carrying the machine uphill after each glide,
and could make at least ten glides in the time required for one in the
other way. But when we came to try it, we found that a wind of seventeen
miles, as measured by Richards' anemometer, instead of sustaining the
machine with its operator, a total weight of 240 lbs., at an angle of
incidence of three degrees, in reality would not sustain the machine
alone--100 lbs.--at this angle. Its lifting capacity seemed scarcely one
third of the calculated amount. In order to make sure that this was not
due to the porosity of the cloth, we constructed two small experimental
surfaces of equal size, one of which was air-proofed and the other left
in its natural state; but we could detect no difference in their lifting
powers. For a time we were led t