436 BELL 



Chanute, and I should like very much to see him given due credit for 

 the very important work which he has done. 



DISCUSSION BY PROF. A. F. ZAHM, OF THE CATHOLIC UNIVERSITY 



OF AMERICA. 



I fully concur with Dr. Bell in the opinion that aerial locomotion is 

 practicable, and is likely soon to be of great moment in the affairs of 

 the world. For the progress of this science, during the past decade or 

 two, has been as positive, as continuous, as substantial as that of any 

 branch of engineering or of architecture. Constantly and quietly, in 

 various parts of the world, men have grappled with the difficulties of 

 this apparently hopeless enterprise, and now, I believe, we are about 

 to enjoy the fruitful and splendid issue of their labors. 



The subject of aerial locomotion may be divided into four main 

 branches : first, the science of captive and free balloons ; second, the 

 science of motor balloons ; third, the science of gliding and soaring 

 machines; fourth, the science of dynamic flying-machines. Each of 

 these has had its ardent advocates, and each is, I believe, practically 

 feasible. 



The first branch, or that of captive and free balloons, is already a 

 practical science, inasmuch as such balloons perform substantially the 

 functions for which they are designed. The captive balloon can be 

 sent aloft safely in all kinds of weather for taking observations, and 

 making maps of the neighboring region, even in winds of upwards of 

 forty miles an hour. The free balloon, likewise, is comparatively safe 

 when made by an experienced manufacturer and managed by a properly 

 trained pilot. Such balloons may be kept aloft for days, or even 

 weeks, traversing, in that time, hundreds of miles, or possibly the 

 width of a continent, if the wind be favorable. But, though we grant 

 the practicability of balloons of this type, it must be said also that their 

 functions are limited ; their chief usefulness thus far being for the study 

 of the atmosphere, for observations of the land beneath, for military ope- 

 rations, for public exhibitions, and now recently, for racing and sport. 



The ideal of the motor balloon is more important and more difficult, 

 though it also seems about to be realized. The function of such craft 

 is to go forth in all kinds of ordinary weather, to run in all directions, 

 with or against the wind, scores of miles at a stretch, and to remain 

 under perfect control. Salverda has shown, by reference to the yearly 

 wind records at Paris, that aerial navigation may be practically real- 

 ized, for that locality, when a vessel can be driven twenty-eight miles 

 an hour. Is such achievement possible? More than a decade ago 



