THE ROYAL ARTILLERY INSTITUTION. 
65 
vertical spread the point of impact will be so much the higher, and if a 
correction is made for this the cover will be again struck; there is 
therefore no alternative but to reduce the charge. If, on the contrary, 
rather too small a charge has been chosen (and therefore a larger angle 
of descent), the trajectory will again pass through the point D, and, 
in consequence of its greater curvature, will strike below the point 
T (Fig. 8). . 
Fig 8, 
In this case a correction might be effected by increasing the elevation. 
The result is the same if the charge and elevation are obtained by 
formula (2). Fig. 9 shows the consequences of too large a charge. 
Fig. 9. 
The trajectory would strike the intended point of impact, but that, 
owing to its flatness, the projectiles are intercepted by the screen D ; 
so that, when using this formula also, too heavy a charge is dis¬ 
advantageous. 
If, on the other hand, the next smaller charge (and therefore the 
next larger angle of descent) is taken (Fig. 10), it will be possible 
to make small corrections by increasing, or even diminishing, the 
elevation. 
Fig. 10. 
Whether the charge and elevation be obtained by formula (1) or (2), 
it is always better to have the charge rather too small than too 
large. By the more curved path thus involved some striking power is 
lost, it is true, but the mark will not be overshot, and if the projectiles 
strike too low they can be made to hit the object of aim by increasing 
the elevation. 
Ex. 3.—A battery armed with short 15 c.m. B.L. guns is constructed 
on the prolongation of the capital of a work at a distance of 850 metres 
