545 
ADJUSTING CLINOMETER PLANES 
OF ORDNANCE. 
A PROPOSAL TO LEVEL GUNS ACROSS TRUNNIONS BY 
A SPECIAL. SPIRIT-LEVEL. 
BY 
CAPTAIN W. E. DONOHUE, R.A., L.0.M. 
Taz clinometer plane on a gun should be parallel with the axis of the 
gun and trunnions. 
The ordinary method of levelling the gun is to place a long straight- 
edge in the bore (see Fig. 2) and adjust with an ordinary spirit-level. 
Fie. 2. 
If great care is taken, a good horizontal position can be obtained by 
this means ; but with a narrow straight-edge there is a danger in the 
straight-edge being slightly inclined (see Fig. 3), one edge will there- 
Fig. 3. 
Sketch showing straight-edge in bore out of the vertical. 
fore be slightly higher than the other, and should the level get slightly 
1. vol, xxin, 
