artillery in coast defence. 
477 
The process is shortly as follows : The operator at the instrument, 
who has been informed by the Fire Commander of the ship, and the 
portion of it, if any, which he wishes to attack, follows up the object 
until he receives a signal from the group that they are ready to lay. 
The instrument is provided with a pencil which, as the telescope is 
moved, traces on a slate the course followed by the object on which 
the telescope is directed. As soon then as he receives the signal he 
traces the course of the vessel for, say, a half-minute and then “ pre¬ 
dicts/’ by reference to this course, where the object will be at the end 
of another half-minute; certain corrections have to be made, as for 
drift (the guns being laid by training arc and not by tangent scale for 
direction) ; for travel during time of flight (no time of firing enters 
into this case, as the guns are fired electrically from the position-finding 
station, at the moment when the object comes over the predicted posi¬ 
tion) ; for powder, length of ship, and tide; but these corrections are 
made, simply, by the application of scales. The point at which the 
gun must be laid, in order to hit the ship in the selected part as she 
comes over the predicted position, having thus been found and marked 
on the slate, the pencil of the instrument is brought over this spot; a 
signal is then sent to the group that the training and range, then 
showing on the dials, are those at which the gun is to be laid. The 
pencil is then brought over the predicted position, and as the ship 
crosses the cross-wires of the telescope the operator fires the guns. 
The observation of result, and correction of error of the shot is 
effected very easily by means of a flexible finger attached to the instru¬ 
ment ; the cross-wires of the telescope being brought on to the splash, 
the flexible finger is brought over the point aimed at, thus auto¬ 
matically showing for the next shot the correction required; for if the 
pencil is brought over the next predicted position of the object the 
finger will show the point that must be aimed at. 
This system gives the most perfect division of labour; the Fire 
Commander can devote his entire attention to the effect produced by 
his fire on the enemy; the operator makes all corrections to ensure 
the trajectory passing through the desired spot; and the Group Officer 
can devote his entire attention to the superintendence of the fire dis¬ 
cipline of his group. 
The Group Officer has control of the fire to the extent that his 
group cannot be fired without his orders, so ensuring that the guns 
are properly laid; also the prediction can not be made until his order 
to lay is given; a switch, which controls the firing current for the 
whole group, and worked by a dial number under the Group Officer’s 
orders being placed in the group. 
A firing plug, which makes another controllable break in the firing 
current, is placed in the circuit for each gun, under charge of the 
Gun-Captain, who does not insert it until he is satisfied that his gun is 
correctly laid at the predicted range and training, and no number is 
in danger from the recoil. Thus if any one gun of the group is not 
ready, and the Group Officer, in order not to lose the prediction, gives 
the order to commence firing, that particular gun will not be fired. 
As regards the advantages and disadvantages of the three systems. 
