ARTILLERY IN COAST DEFENCE. 
467 
on account of the bursting charge beiug large enough to give a visible 
burst and the advantage of using the same projectile throughout; 
or segment from R.B.L. With heavy guns when time shrapnel is not 
to be used from the salvo guns, both they and the ranging guns 
would use the same projectiles. 
When ranging with percussion shell, the object should be to get the 
shell to burst to windward of the target, so that the drifting smoke 
may give a clear indication of the result of the shot; sufficient deflec¬ 
tion must, therefore, be given to carry the shot to windward, unless the 
target has a broad front, when it would be sufficient to lay on the 
windward flank, without more deflection than is necessary to counteract 
the wind and bring the shot on to the point aimed at. The salvo 
guns will, of course, only have this latter deflection if the object is 
advancing or retiring direct. If the object is making a diagonal 
course, with regard to the line of fire, deflection will also be necessary 
to compensate for the transverse movement during the time of flight; 
which may be taken as five seconds with R.M.L. guns at medium 
ranges. A rough rule, to find the number of minutes deflection neces¬ 
sary, when no instrument is available by which the angle moved through 
by the target in a given time can be measured, is to multiply the 
(supposed) rate of the object, in miles per hour, by five. In the case 
of a diagonal course, the distance between successive predicted ranges 
may be decreased, as also the difference between the elevations of the 
ranging and salvo guns. An object in motion cannot remain at a 
constant range unless it moves on the arc of a circle, in such an 
unlikely case the range could be found as for a standing target. 
The system of fire control without a range-finder when the object is 
stationary is briefly as follows :—In this case all the guns of a group are 
used to find the range. The first shot, from the leeward gun, is fired at 
the estimated range of the object, the second with so much added to or 
subtracted from it as will ensure its falling on the opposite side of the ob¬ 
ject; if successful in this, the object is now included between two known 
ranges; this is called obtaining the “ long bracket;” the next shot is 
fired at the mean of this bracket, and the next at the mean of the last 
elevation that gave a + and the last that gave a — ; this process is 
repeated until the object has been included between two elevations 
(ranges) which only differ by 50 yards; called the <f short bracket 
a “ verifying series,” of usually four shots, is then fired at the mean 
elevation of the short bracket; if the result is that half of the verifying 
shots go over and half under, the mean trajectory passes approxi¬ 
mately through the water-line of the object; if that object is a low one, 
such as a boat, we should accept this as the correct range; if the object is 
a high one, such as the side of a ship, we must raise the mean trajectory 
by adding on 25 yards elevation ; anything over five feet should be 
looked upon as a high target. If three-fourths of the verifying series 
are overs, the mean trajectory passes above the water-line, and we 
should keep to that range with a high target, but reduce by 25 yards 
for a low one; if three-fourths are unders, the mean trajectory is short 
of the object, and the range must be increased. If the first three 
shots at a low target, or the first two at a high one, are under, the 
