56 
ON THE RANGE INDICATOR DIAL. 
being also intermediate marks to show the fifties. The figures on the 
front would be covered by the same figures on the back, so that, those 
on the front being arranged as on a clock face, the figures on the back 
would, of course, go round the reverse way. (Vide fig.) Against the 
back face would also be placed another smaller or inner dial, similarly 
divided to the outer one. This inner dial would revolve on an axle 
which would be fixed to the centre of the outer dial. It would be 
necessary to place a thin metal washer between the two dials to enable 
the inner one to be turned easily. The axle should be hollow, and a 
pin would pass through it, to each end of which a hand would be 
rigidly fixed, that which moved on the rear face covering the one on 
the front so that they would both move together and always point in 
the same direction. 
The changes in the number of thousands of yards would only occur 
at long intervals, and they might be shown by figures on tin plates 
placed in a clip at the top of the frame. 
Suppose that the C.O. finds, as the result of his corrections, that 
75 yards must be deducted from the range found by the Range-Finder 
before it is signalled to the guns. He orders the man in charge of the 
Range Indicator Dial to “ deduct 75 yards.” At this word the inner 
dial would be turned till the arrow head marking the zero point on it 
(and which in the first instance corresponded with the zero on the 
outer dial), was moved 75 yards to the right on the outer dial, as 
shown in the figure. Every point on the inner dial would then, of 
course, be 75 yards behind the corresponding point on the outer one. 
When the range is now called from the Range-Finder the hand is made 
to point to that range on the inner dial. Say that 2400 is called from 
the Range-Finder, the figure 2 having been placed in the clip at the 
top to show the thousands, the hand at the back is made to point to 
400 on the inner dial, this corresponds with 325 on the outer dial, and 
the hand on the front face will therefore also point to 325. 
The ranges found by the Range-Finder can then continue to be 
