2o8                                FLYING   MACHINES.
the society (fig. 74). The strongest winds in which I practised
had a velocity which I estimated at between 15 and 16 miles
per hour. By running I obtained an additional velocity of 7
miles an hour, making the total relative velocity 23 miles an
hour, which was required for soaring. Under these circum-
stances the first part of myflight was almost horizontal, and
the alighting was always a gentle one. . . . Each apparatus
had a vertical and horizontal tail, without which it is imprac-
ticable to practice in the wind. In conclusion, I will remark
that sailing flight near the earth's surface must be much more
difficult than at greater heights, where the wind blows more
regularly, while every irregularity of the ground at lower levels
starts whirls in the air.
In the opinion of the writer of these lines Herr Lilienthal
has attacked the most difficult, and perhaps the most im-
portant, of the many problems which must be solved before
success can be hoped for in navigating the air with flying
machines. He has engaged in the effort to work out the
maintenance of equilibrium in flight, and to learn the
science of the bird. He has made a good beginning, and
seems to be in a fair way to accomplish some success in
riding on the wind.
We have already seen that this has been tried before, and
that (to say nothing of ancient myths) J. B. Dante, Paul
Guidotti, Francisco Orujo, and Captain Le Bris, all met
with partial success in soaring. Singularly enough all four
met also with the same accident—i.e., a broken leg, in con-
sequence of the loss of equipoise. Herr Lilienthal has
greater chances of success, not only because he seems to
have set about his experiments only after thorough investi-
gation and consideration, but also because mechanical
knowledge as well as constructive methods and workman-
ship have greatly improved since even Le Bris's time. Be-
sides this, we have the gliding exploit of M. Mouillard,
whose experiment has already been related, and that of
M. Ader, which is yet to be mentioned.
Most of the capable inventors who have undertaken to
solve the problem of flight have first concerned themselves
with the question of motive power, and we shall see here-
after that very great progress has been achieved in this
direction since 1890; but no amount of motive power will
avail unless the apparatus to which it is applied is stable in
the air—unless it,can rise, sail, and come down again with-
out danger of losing its equipoise. As has already been
said, safety is the first requisite, and until this is assured,
all the other elements of success will be unavailable.
Herr Lilienthal has eliminated for the present the ques-
tion of motive power, by undertaking to utilize ascending
trends of wind, like a sailing bird , and if he succeeds in