434 
AUTO-SIGHTS. 
They are as follows : - - 
& 
Let G, an automatically sighted gun at a height GS, or h' feet, above 
SL, the sea level, be correctly laid on T, a target which is at a range GT, 
or R yards. Then the trajectory will pass through T ; that is the gun 
wiil have the tangent elevation due to R. If the target now moves to 
another position, C ; such that the line of sight in following it has to 
be raised (Fig. i.) or depressed (Fig. 2.) through any angle 0 , the 
trajectory will pass through C and the gun will have the tangent 
elevation due to the range GC. In other words if, when the gun has 
<? 
