140 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



plane type there must be some means provided to secure fore and aft 

 stability and also lateral stability. 



A large number of plans have been proposed for the accomplish- 

 ment of these ends, some based upon the skill of the aviator, others 

 operated automatically, and still others employing a combination 

 of both. At the present time no aeroplane has yet been publicly 

 exhibited which is provided with automatic control. There is little 

 difference of opinion as to the desirability of some form of automatic 

 control. 



The Wright aeroplane does not attempt to accomplish this, but 

 depends entirely upon the skill of the aviator to secure both lateral 

 and longitudinal equilibrium; but it is understood that a device for 

 this purpose is one of the next to be brought forward by them. Much* 

 of the success of the Wright brothers has been due to their logical 

 procedure in the development of the aeroplane, taking the essentials, 

 step by step, rather than attempting everything at once, as is so often 

 the practice with inexperienced inventors. 



The aviator's task is much more difficult than that of the chauffeur. 

 With the chauffeur, while it is true that it requires his constant atten- 

 tion to guide his machine, yet he is traveling on a roadway where he 

 can have due warning through sight of the turns and irregularities 

 of the course. 



The fundamental difference between operating the aeroplane and 

 the automobile is that the former is traveling along an aerial high- 

 way which has manifold humps and ridges, eddies and gusts, and 

 since the air is invisible he can not see these irregularities and inequali- 

 ties of his path, and consequently can not provide for them until he 

 has actually encountered them. He must feel the road since he can 

 not see it. 



Some form of automatic control whereby the machine itself 

 promptly corrects for the inequalities of its path is evidently very 

 desirable. As stated above, a large number of plans for doing this 

 have been proposed, many of them based on gyrostatic action, mov- 

 able side planes, revolving surfaces, warped surfaces, etc. A solu- 

 tion of this problem may be considered as one of the next important 

 steps forward in the development of the aeroplane. 



HI. Hydromechanic Relations. 



SOME GENERAL RELATIONS BETWEEN SHIPS IN AIR AND IN WAITER. 



At the present moment so many minds are engaged upon the gen- 

 eral problem of aerial navigation that any method by which a broad 

 forecast of the subject can be made is particularly desirable. Each 

 branch of the subject has its advocates, each believing implicitly in 

 the superiority of his method. On the one hand the adherents of 



