reille: anti-aircraft firing 479 



(4) The ballistic coordinates (angle of departure, fuse-set- 

 ting) are read on the diagram of the trajectorial and isopyrical 

 curves; a diagram, on which the point to be aimed at has just been 

 fixed by the knowledge of its angle of sight and of its altitude (or 

 merely of its abscissa and ordinate). 



(5). If one proceeds by measurement of angular velocities 

 instead of by measurements of Hnear velocities the instruments 

 used are the continuous electric cinemometers already men- 

 tioned above, and then the extrapolation is determined as 

 follows : 



(a) Azimuth. — The extrapolated azimuth is obtained by the 

 extrapolation of the horizontal angular velocity and this in 

 starting from the last azimuth in which the flying machine has 

 been observed prior to the firing of the shot. 



(b) Angle of Sight. — In the same way, the extrapolated angle 

 of sight is obtained by the extrapolation of the angular velocity 

 in the plane of sight where the flying machine has been observed 

 prior to the firing of the shot. 



CONCLUSIONS 



In ending this comment, which inevitably is of a very gen- 

 eral character, it seems necessary to insist upon the great im- 

 portance that should be attached to the fact that, as far as 

 possible, the nature of the firing conditions should be such as 

 not to disturb the continuity of the flight of the flying machine 

 between the moment at which the measurements that deter- 

 mine the firing data have been taken arid the moment at which 

 the shot reaches its destination. 



As has been said, a flying machine may cover about 700 

 meters during the flight of the projectile. During this period 

 the race is most unequal. 



On one hand, the projectile, just carrying away the measure- 

 ments and the intentions of the battery commander, is merely an 

 inert instrument of a previous will. It clings helplessly to its 

 trajectory and will inevitably burst once the combustion of its 

 fuse has come to an end. On the other hand, the aerial ship 

 has maintained the full power of her free will, her trajectory is 



