269 
A.TJTOM1A.TIC SIGHTING. 
BY 
COLONEL H. S. S. W AT KIN, C.B., R.A. 
Chief Inspector of Position Finding. 
TIIE question of Automatic Sighting is now so much to the fore, 
and so many statements have been made as to their capabilities, that 
I think it might be of interest to look into the question both from a 
theoretical and practical point of view. 
An automatic sight is one which finds the range and at the same 
time sets the gun to the elevation due to that range, by the mere act 
of laying the sights on the water line of the object. It is a sine qua 
non 
(1) . That the gun must be at a certain known height above the 
water level; the greater the height the greater the 
accuracy. 
(2) . That the platform or emplacement must be truly level all 
round, and must continue so during firing, and this to a 
far greater accuracy than we have hitherto been accus¬ 
tomed to in our coast guns. 
The theory of the apparatus will be seen from the following:—■ 
Let F B represent a gun, placed at a height B D above the sea-level 
' 1 ■ , , ■ JS 
Fig. 1. 
D C, and at such an angle of elevation that a shot fired from it will hit 
the water at the point C. Draw E B parallel to D C. It is clear that 
under these conditions, if the tangent scale A F is raised to a^height 
A F, representing the elevation due to the range B C , the object C 
will be in line with the fore and hind sight. 
6. VOL. XXV. 
