188 
MINUTES OF PROCEEDINGS OF 
Both guns having the angle-finders placed on them, and the cross wires 
of the main telescopes are laid on the same object, which should not he 
less than 1000 yds. distant. Then the short telescope of the right angle- 
finder is laid carefully on the white face of the other angle-finder, and 
the number (oc) given by the index noted. The short telescope of the 
right gun is now laid on the muzzle of the left gun, and the index num¬ 
ber (y) is noted. Subtract this last number from the first, and we have 
(x — y) = z. or (x + 100 — y) = 2 if y be greater than x. 
Set the tape arrow on line E, to the distance between the guns—that is 
the actual measured distance, say 41J yds., and opposite the number 
(x — y) or 2 on Gr. Make a scratch on the top surface of the roller. 
Now place the guns about 55 yds. apart, and repeat the operation as 
before, getting x' y for index numbers; it will now be found that when 
the tape mark is set to the true distance between the guns, say 55 \ yds,, 
that the scratch previously made ought to come exactly opposite x' — y' 
on line Gr, if this is the case, the operation has been correctly performed. 
Make a mark in the shape of a gun at the scratch, and, to prevent future 
confusion, write over this scratch the nature of the gun, as—9-pr. R.M.L. 
Precautions to be observed. 
The distance between the guns is to be measured in this operation from 
the axis of one main telescope to the axis of the other main telescope. 
Let the distance between the guns be always at least twenty times the 
distance between the centre of the white face of the angle-finder and the 
muzzle of the gun. When, however, the theory of the mechanical calcu¬ 
lator, as described later on, is thoroughly understood, this last rule need 
not be followed. 
One roller having been marked for a particular description of gun the 
other rollers are taken; the tape-mark is set at 50, and each roller is then 
marked with the gun-mark on the inner top ring, opposite to the same 
number on Gr, that the gun-mark on the specimen roller, first operated 
upon, points to; the rollers being thus complete, if the common tape, such 
as is usually sold in round cases, is employed, the distance between the 
guns should be measured from like part to like (say from handspike to 
handspike), when the range is being found; if one of my peculiar tapes, 
terminated by a hook, is employed, from inner trail-handle to inner trail- 
handle is the best; this will require the tape to be shortened about 15 
inches, to allow for the projections of the handles. 
It is now supposed that a battery is furnished with two sets of range¬ 
finders, placed on guns 1, 3, 4 and 6, and that it is required to instruct 
the men in the use of the range-finders. 
Before doing so, it would be of the greatest use to peg out a measured 
range. To effect this, let an officer select ground over which a battery, or 
at least two guns, can manoeuvre for about 500 yards. Let him then very 
carefully, with the instruments, and with large and varying bases, get the 
distance of an object, distant say 1500 yds., then let him peg out a range 
1500, 1550, 1600, 1650, &c., for 500 yds. 
At drill he will move his battery up and down this range, showing to 
his men that they have got the range 5, 10, or 50 yds. wrong. 
