490 RANGING BY CLINOMETER. 
As to the graduation of the curve :— 
It is obviously absurd to graduate an instrument which measures 
quadrant elevation in yards, while division into degrees and minutes is 
inconvenient. It seems as if the best thing would be to take some con- 
veniently sized unit which would mean something to a gunner, for 
instance a unit can be found, the addition or substraction of which from 
the quadrant elevation will raise or lower the trajectory as many fect as 
there are hundreds of yards in the range. 
11°46 minutes is such a unit, and 11:46 minutes measured at the 
circumference of an arc struck at 380 inches radius (as is the arc in the 
design) measures one tenth of an inch. 
This is a convenient unit for laying, and it can be further sub- 
uivided by a vernier so as to read 1:146 minutes, as is done in the 
design which reads from 20 units depression to 90 units elevation, or 
from about 4 degrees depression to 18 degrees elevation. 
There is no doubt that such an instrument would be most usefal as 
soon as the ranging was complete and ordinary fire established, and it 
is probable that the use of such a clinometer would also lead to quicker 
ranging. 
For, instead of the tedious repetition of resetting the sight, replacing 
in the sight hole or bracket, and then relaying the gun, which at 
present follows every alteration in elevation, the work could be sub- 
divided as follows :— 
One number at the gun would stand close to the clinometer and 
follow up every alteration given by the battery commander; this he 
would do by a simple turn of the thumb wheel, aud there would be no 
necessity to remove the clinometer from the bracket. Another number 
at the gun would follow up each alteration of level by bringing the 
bubble into the centre of its run as seen in the prism. 
Such a method would, I am sure, save 10 seconds at least at ae 
alteration of elevation and shorten the process of ranging by between 
1 and 2 minutes. 
I would suggest the following drill :— 
(1). Deliberate advance. 
The commanding officer would advance as usual, determine the 
elevation due to range and angle of sight and have all the clinometers 
set at one given elevation before advancing. 
On coming into action, No. 4 would place the set clinometer on the 
bracket, level it by the cross level and stand close to the sight to make 
any alterations ordered by the commanding officer; No. 1 would go to 
the clevating wheel and bring the bubble of the level to the middle of 
its run as seen in the prism after every alteration in elevation. 
(2). Direct advance. 
The gun in the command farthest from the flank which opens fire 
would take the quadrant elevation after laying by tangent sight, and 
communicate it as soon as possible to the commanding officer, when the 
same method as before would be adopted. 
