reille: anti-aircraft firing 475 



To sum up, the problem of anti-aircraft firing, after many ex- 

 periments, is at present, if not solved, at least plainly laid out in 

 the following way: 



To be preliminarily measured: (1) altitude of the flying ma- 

 chine; (2) its orientation and its velocity (angular or hnear); 



(3) extrapolation or prediction of the point to be aimed at; 



(4) wherefrom the knowledge of the azimuth of the said point; 



(5) wherefrom, too, in the azimuth the reading on a diagram 

 of the ballistic coordinates of the said point (trajectory and 

 isopyre) as functions of its geometric coordinates (angle of 

 sight and altitude). 



Fig. 5. 



Finally, a word in regard to the methods of measuring: 



(1). The altitude (h) is measured by triangulation from a 

 large observation base. 



The flying machine is the summit of a pyramid occupying 

 the space S. s. A. B. placed on the horizontal plant H (fig. 5). 

 A. B. is the line of measurement called the horizontal base, at 

 the two extremities of which are two posts of observation, the 

 distance between them being known, s isvthe horizontal projec- 

 tion of the flying machine. 



Any triangulation made in order to solve the pyramid will 

 give the knowledge of the altitude h. 



