SHORT NOTES ON PROEESSIONAL SUBJECTS. 
173 
110. Note on the new Method oe Controlling the Recoil op 
Heavy Guns at Proof, by Major E. Maitland, R.A. 
Up to the present time, heavy guns have been carried down by rail from the Gun 
Eactories on trucks to the butt, and have then been mounted for proof by means of 
a crane (constructed to lift 30 tons), on a strong iron carriage, fitted with expanding- 
sides, to take guns of weights varying from 12 to 38 tons, 
It is now proposed to extend the rails opposite the firing bays, so that a heavy 
gun may be fired from a specially constructed travelling truck; thus dispensing with 
the expanding carriage and crane altogether. The axis of the gun on the truck 
will be parallel to the rails, and the truck and gun will recoil along the line. There 
are three adjacent bays formed to receive the proof projectiles of heavy guns. In 
order to utilize them all, it is only necessary to curve the line of rail sufficiently 
to permit lines drawn from the bays to form tangents to the curve; the distance 
of the firing points from the butt being enough to render the angle of incidence 
unimportant. 
By carrying back the rail in a curve of contrary flexure, a second series of firing- 
points is obtained, at an increased distance from the bays. The railway is then 
carried back in a straight line, so that from the most distant firing point the recoil 
may be direct. On account of the nature of the ground, it is found expedient to 
bring the gun to a standstill within a distance of 120 ft. from the rearmost firing 
position. Assuming the weight of the heaviest gun likely to be used at 80 tons, 
and the weight of the truck at 5 tons, we have JF = 85. Supposing this gun to 
throw a shot of 1600 lbs., with a muzzle velocity of 1400 ft., we have 
initial velocity of recoil = V — ^ = 11*76 f.s. 
Hence the work contained in the gun and truck at starting will be 
—— = 182*6 foot tons. 
*9 
Allowing a margin for exceptional cases, we will put this energy at 250 foot tons. 
The work done in stopping the recoil is given by the formula 
which may be put 
W (sin a + /jl cos a) S, 
^ (y + /*»); 
/x being the co-efficient of friction, which, with strong rough rails and truck wheels, 
will not be less than -g-J-f-g-, or '0067. Hence 
7FF 2 
and this will give the height of the slope (or y) at any given distance x, whether the 
railway be horizontal, or carried up an inclined plane, or so constructed that the 
incline be an upward curve. 
In the present case, since x = 120 ft., 
y — ^ _ -0067 x 120 = 2-14 ft.; 
.*. tan a 
2*14 
120 
, and a — 
1° l'*5. 
26 
