SOME AKROlsrATTTlCAL EXPERIMENTS. 187 



were successfully encountered nuich g-reater in violence tliiin an}' 

 which previous experimenters had dared to attempt. 



My own active interest in aeronautical problems dates hack to the 

 death of Lilienthal in 1S1X3. The l)rief notice of his death which 

 appeared in the telegraphic news at that time aroused a passive inter- 

 est which had existed from my childhood and led me to take down 

 from the shelves of our home library a l)ook on Animal Mechanism, by 

 Professor Marey, which I had already read several times. From this 

 I was led to read more modern works, and as ni}^ brother soon became 

 ecpially interesti^d with myself we soon passed fi'om the reading to the 

 thinking, and linally to the working stage. It seemed to us that the 

 main reason why the problem had remained so long unsolved was that 

 no one had l)iM'n aV)le to obtain any adequate practict'. We figured 

 that Lilienthal in live 5'ears of time had spent only al)out live hours 

 in actual gliding through the air. The wonder was not that he had 

 done so little, but that he had accomplished so much. It would not be 

 considered at all safe for a bicycle rider to attempt to ride through a 

 crowded cit>^ street after only live hours' practice, spread out in bits of 

 ten seconds each over a period of live years; yet Lilienthal with this 

 brief practice was remarkably successful in meeting the fluctuations 

 and eddies of wi)id gusts. We thought that if some method could be 

 found b}' which it would )>e possil)]e to practice by the hour instead of 

 by the second there would be hope of advancing the solution of a very 

 difficult problem. It seemed feasil)le to do this by building a machine 

 which would be sustained at a speed of 18 mil(\s per hour, and then 

 finding a locality where winds of this velocity were connnon. \\'ith 

 these conditions, a rope attached to tlie machine to keep it from floating 

 backward would answer very nearly the same purpose as a propeller 

 driven hy a motor, and it would be possible to practice by the hour, 

 and without any serious danger, as it would not be necessary to rise 

 far from the ground, and the machine would not ha^■e any forward 

 motion at all. We found, according to the accepted tables of air 

 pressures on curved surfaces that a machine spreading 200 square feet 

 of wing surface would ])e sufficient for our purpose, and that places 

 could easily be found along the .Vtlantic coast where winds of 10 to 25 

 miles were not at all unconnnon. When the winds were low it was 

 our plan to glide from the tops of sand hills, and when they were suf- 

 ficiently strong to use a rope for our motoi- and Hy over one sj ot. 

 Our next work was to draw up the, plans for a suitable machine. 

 Aft(M- much study we finally concluded that tails were a source of 

 trouble i-ather than of assistance; and thei-(>foi'(> we decided to dispense 

 with them altogether. It seemed I'easonable that if the Itody of the 

 operator could be ])laced in a horizontal position instead of tlu^ uprighl, 

 as in the machines of Lilienthal. Pilcher. and Chanute, the wind resist- 

 ance could be^ very matei'ially i-edu((Hl. since only f scjuare foot 



