ARTILLERY IN COAST DEFENCE. 
479 
action, should its particular instrument become from any cause unser¬ 
viceable. Each group could, however, be directed at a different object 
or part of a vessel if required. Wifch depression range-finding system 
there should always be a second instrument in reserve. 
In the lecture on “Fire Tactics 93 it was pointed out that it is very 
desirable that we should have the power of obtaining simultaneous 
hits, as close together as possible ; this is always of importance as 
regards the salvo from each group, and is also desirable as regards the 
fire of a work as a whole. 
With any system of fire control in which the guns are laid for direc¬ 
tion by sights, the possibility of concentrating the fire on a particular 
spot is obtained. This is not the case with the position-finding 
system, as the guns are then laid by the arcs, which are oriented alike, 
the lines of fire are, therefore, parallel. Suppose a ship, breadth 60 
feet, is engaging end-on a group of four guns, fought by position- 
finder, the distance from muzzle to muzzle being 24 feet, the lines of 
fire of the outermost guns will be 72 feet apart, and their projectiles 
will, therefore, miss the vessel. This is a serious disadvantage at 
present to the position-finding system; it can, of course, be mitigated 
by sub-division of the groups, but this necessitates a large increase of 
specialists and instruments, multiplication of lines of communication, 
a larger number of Group Officers, and, most important of all, we then 
lose the power of firing large salvos simultaneously. 
As regards simultaneous hits, the position-finding system ensures 
the guns of a group being fired absolutely at the same instant; with 
depression range-finding system we do not get this absolutely as the 
guns are fired by word of command; there is no reason, however, why 
the guns should not be fired electrically by the Group Officer, if the 
proper fittings were provided, so that this defect cannot be looked 
upon as inherent in the depression range-finding system. As regards 
the possibility of obtaining simultaneous hits from a number of 
groups, this is practicable with depression range-finder, the Fire Com¬ 
mander ordering the Group Officers to all lay for a given range; with 
position-finder it is not practicable, the Fire Commander having no 
possible means of pointing out' a special spot for prediction to all the 
operators. 
An examination of practice reports seems to show that there is not 
much difference in the effectiveness. of fire conducted by the two 
systems; if any exists it is in favour of the depression range-finder. 
At practice, however, usually only one or two guns of a group are 
manned, if the whole were fired, probably the percentage of hits would 
be much more in favour of the depression range-finder than it is at 
present. 
It may be noted that if absence of smoke permits laying for direc¬ 
tion by sights, the position-finder can be used in the same way as the 
depression range-finder, and being an improved and larger instrument, 
correcting automatically for displacement, and requiring no calculations 
on the part of the Fire Commander, should give the highest possible 
results. The system of control in this case would be the same as with 
64 
