THE ROYAL ARTILLERY INSTITUTION. 
43 
THE 
ACTION OF DISCHARGE UPON A FIELD 
GUN-CARRIAGE, 
AS ILLUSTRATED BY 
THE 16-PR. M.L.R. GUN OF 12 CWT. 
BY 
CAPTAIN W. KEMMIS, R.A. 
If a 16-pr. gun-carriage of tlie latest construction be unlimbered 
upon level ground, and the length of the body of the axle (49"*5) be 
taken as the distance between the wheels, or supporting points, the 
statical breaking weight of the box-girder axletree-bed, applied in a 
vertical direction midway between the supports, will be found, by cal¬ 
culation in the usual way, to be 23’22 tons. 
Assuming 30° (which there is no doubt is under the mark) to be 
the elevation at which the gun is fired when the limit of 23*22 tons 
vertical pressure upon the axletree and bed is reached, a few deductions 
as to the statical strains upon the carriage may be made. In doing so, 
for sake of simplicity, the forces called into action upon discharge will 
be taken as acting in one plane—namely, the vertical plane through 
the longitudinal axis of the gun; in fact, any strain due to the twist of 
the rifling, being comparatively small,* will be neglected. 
* In severe trials, this strain makes itself evident by the right capsquare giving way, and also 
the right socket supporting the elevating-screw box. 
