312 
ARTILLERY IN COAST DEFENCE. 
with regard to the ammunition to be used and the rate of firing, and 
the orders to commence and cease firing. If orders have to be sent 
by orderlies they should be sent on the authorised message form, 
properly addressed, and with the hour of departure entered, officers 
receiving them should initial them and mark time of receipt. 
For indicating objectives various instrumental systems have been 
proposed, but none have been so far adopted, an objection to such 
systems is the introduction of additional instruments, requiring highly- 
trained men to work them, and the loss of time in taking the obser¬ 
vations. The system of indicating by squares seems so far to have given 
the best results. In this system all the charts of the sea area are divided 
up into squares of 400 yards side and numbered. On the Section 
Commander’s chart the squares on which the groups of a given fort 
can bear are marked with a band of colour, each fort having a colour 
allotted to it, and the band is made darker or lighter according to the 
number of groups that can bear. The chart being fixed under the 
position-finding instrument at the Section Commander’s station the 
pointer attached to the instrument shows in which square the object is 
when the telescope is directed on it. The Fort Commander’s chart is 
similarly divided and numbered, and the squares show the groups 
which can bear on them ; and if he has a position-finder at his station 
the chart is mounted under it, then, by bringing the pencil over a 
given square and looking through the telescope, any object in that 
square will be seen. A similar chart is mounted under each position¬ 
finding instrument. 
When guns are fought by depression range-finder the Group Officers 
and depression range-finder observers are supplied with cards showing 
the range and training to the centre of each square on which they 
can bear. Electric-Light Officers are supplied with similar cards. 
The system of using these charts and cards is as follows:—The 
Section Commander’s observer picks up the object with the instrument 
and notes on which square it is ; the number of the square is tele¬ 
graphed by the Section Commander to the Fort Commander the fire 
of whose fort he wishes to direct on that object; this number is 
passed on by the Fort Commander to Group Officers and to depression 
range-finder observers, who, by aid of their cards, direct the guns 
and instruments on the square, and are so made acquainted with the 
object on which fire is to be directed. 
As regards the means of finding and communicating ranges, the 
instruments in use for coast batteries are the position-finder and the 
depression range-finder, and it is only with these that ranges to mov¬ 
ing objects can be sufficiently quickly and accurately taken; though, 
of course, any range-finder available could be used for a standing 
object, or from a high battery the angle of depression could be 
measured by laying a gun on the object, point blank, and measuring 
the angle of depression with a clinometer, using the formula 
Height of gun in feet x 1146 -n • 
——2 - p. --— -=Kange m yards. 
Minutes m z of depression 
The position-finders are worked by specially trained men of the 
