SOME AERONAUTICAL EXPERIMENTS. 139 



We th(Mi turned our {ittention to nisiking a series of actual nietisure- 

 ments of the lift and drift of tlie machine under various loiuls. So far 

 as we were aware this had never previously i)een done with any full- 

 size machine. The results obtained were most astonishino-, for it 

 appeared that the total horizontal pull of the machine, while sustain- 

 ing a weight of 52 pounds, was oidy S.5 pounds, which was less than 

 had previously been estimated for head resistance of the framing alone. 

 Making allowance for the weight carried, it appeared that the head 

 resistance of the framing was but little more than 50 p(>r cent of the 

 amount which Mr. Chanute had estimated as tho head resistance of 

 the framing of his machine. On the other hand, it appeared sadly 

 deficient in lifting power as compared with the calculated lift of curved 

 surfaces of its size. This deficiency we supposed might be due to one 

 or more of the following causes: (1) That the depth of the curvature 

 of oui" surfaces was insufficient. l)eing only about 1 in 22 instead of 1 

 in 12. (2) That the cloth used in our wings was not sufficiently air 

 tight. (?)) That the Lilienthal tables might themselves be somewhat 

 in error. AVe decided to arrang(> our machine for the following year 

 so that the depth of curvature of its surfaces could l)e \aried at will 

 and its covering air-proofed. 



Our attention was next tui'ued to gliding. })ut no Iiill suitable for 

 the purpose could be found near our camp at Kitty Hawk. This com- 

 pelled us to take the machine to a point 4 miles south, where the Kill 

 Devil sand hill rises from the flat sand to a height of more than 100 

 feet. Its main slope is toward the northeast and has an inclination of 

 about 10'. On the day of oui' arrival the wind l)lew about 25 miles 

 an hour, and as we had had no experience at all in gliding we deemed 

 it unsafe to attempt to leave the ground. But on the day following, 

 the wind having subsided to li miles per hour, we made about a dozen 

 glides. It had been the original intention that the operatoi- should 

 run with the machine to ol)tain initial velocitv and assuuK^ the hori- 

 zontal position only after the machine was in free flight. ^\ hen it 

 came time to land he was to resmne the upright position and light on 

 his feet, after the style of previous gliding experimenters. But on 

 actual trial we found it much better to employ the help of two assist- 

 ants in starting, which the peculiar form of our machine enabled us 

 readily to do. and in landing we found that it was entirt^ly practicable 

 to land while still reclining in a horizontal position upon the machine. 

 Although the landings were made while moving at speeds of more than 

 20 miles an hour, neither machine nor operator sufl'ered any injury. 

 The slope of the hill was 9.5-. or a drop of I foot in C). We found 

 that after attaining a speed of al)out 25 or 80 miles with reference to 

 the wind, or lo to 15 miles over the ground, the machine not only 

 glided parallel to the slope of the hill, but greatly increased its speed, 

 thus indicating its ability to glide on a somewhat less angle than i^.5^, 

 when we should feel it safe to rise higher from the surface. The con- 

 trol of the machine proved even blotter than we had dared to expect, 



