546 ADJUSTING CLINOMETER PLANES OF ORDNANCE, 
across the straight-edge (see Fig. 4), a small error will be introduced. 
Fra. 4. 
SET Mince ny DMITA 
Sketch in plan showing the spirit-level laying across the straight-edge, 
For levelling the guns across the trunnions, an instrument as shown in 
Fig. 1 is used. For the larger natures of ordnance, this is a very 
Fie. 1. 
SPIRIT LEVELS —-oo Pes. 
oy Fa a 
inconvenient instrument for carrying about. 
‘The writer, having found it necessary to examine and adjust the 
clinometer planes of guns in localities and under conditions where it 
was inconvenient to carry about instruments which would not stand 
rough usage, constructed a spirit-level with an angle iron base of 
portable size which enables the gun to be levelled across the trunnions 
easily ; and at the same time, when used for levelling the bore of the 
gun, eliminates the possibility of error, previously mentioned, caused 
by the spirit-level getting across the straight-edge, as shown in Fig. 
4. The angle iron spirit-level is shown in position on the trunnion of 
the gun in Fig. 5. 
Fie. 5. 
| 
Sketch showing angle iron spirit-level on trunnion of gun. 
The instrument can be constructed by any Armament Artificer. 
It is considered that a spirit-level so constructed would be a very 
useful instrument for general purposes. 
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