ATMOSPHERIC FRTCTION. 
273 
it long side foremost. The latter device has been tested ex¬ 
perimentally by Mr. Langley. His results are presented in 
table VII, together with corrections for skin-friction made 
by the present writer. 
Table VII. 
Data for Soaring of 30 X 4-8 Inch Plane; Weight , 500 Grammes. 
Soaring 
angle. 
Soaring 
speed. 
Horizontal 
resistance. 
Corrected 
for friction. 
Horse¬ 
load. 
Corrected 
for friction. 
Deg. 
Ft. sec. 
Gms. 
Gms. 
Lbs. 
Lbs. 
10 
40.7 
88 
95.04 
77 
71.3 
5 
49.8 
45 
55.34 
122 
99.2 
2 
65.6 
20 
37.69 
209 
110.9 
The last column shows, after correction for friction, that 
the plane in question may carry about 111 pounds per tow- 
line horse-power at an angle of two degrees if the edge re¬ 
sistance be neglected. This ratio of weight to power is still 
not very large, but it may be augmented by arching the plane 
and by lessening the load. This latter device is being pushed 
to an extraordinary degree by Dr. A. G. Bell, and it will be 
very interesting to learn the horse-load of his most efficient 
kites. 
So much for soaring planes. But these are of less sub¬ 
stantial interest than arched surfaces, which, besides other 
advantages, carry a larger burden per horse-power. This 
fact is duly regarded by modern aeronauticians, both investi¬ 
gators and designers. The Wright brothers, who, after 
Lilienthal and Chanute, have been especially active and suc¬ 
cessful in practical flight, claim for their gliding machine a 
tow-line horse-load as high as 166 pounds at a speed of eigh¬ 
teen miles an hour, and that, too, including the resistance of 
the entire framing. Mr. Herring has reported similar good 
results with a flying model. To secure such efficiency with 
a plane, either square or shaped, as in table VII, the surface 
load would have to be much less than one pound per square 
