356 
MINUTES OE PEOCEEDINGS OE 
our Armstrong B.L. 20-prs.; tlie weight of the projectile is 25 lbs., as was 
that of the Armstrong gun when it was first introduced. The gun weighs 
53 times the weight of the loaded shell, and the charge is a little over one- 
twelfth. The Armstrong B.L. 20-pr. for land service weighs 94 times the 
present projectile, and it weighed 75 times the original projectile at the time 
when the recoil, with a charge of one-eighth, was found so violent and so 
destructive to the carriage, as to lead to a reduction in the rating of the gun. 
The recoil of the Trench gun must therefore be very violent also. This is 
further evident from the following comparison s— 
Armstrong B.L. 20-pr. 
French canon de 12 raye. land service. 
Weight of gun.......,..1345*0 lbs. 1830*0 lbs. 
Carriage and wheels .1277*0 „ 1684*0 „ 
r~* ---—^ 
Charge . 2*2 „ (1) 3*125 (2) 2*5 
Projectile . 25*4 ss 25*0 21*5 
Initial velocity of shell .1066*0 ft. 1142*0 ft. 869*0 ft. 
Calculated shock of recoil per second ... 10*8 „ 8*1 „ 6*9 „ 
The velocities in the last line are found by the formula, 
Velocity of recoil = initial velocity of shot mass 
mass of gun and carriage. 
The actual recoil of the piece is as follows : 
Elevation. 
0° 
6° 
10° 
15° 
ft. 
ft. 
ft. 
ft. 
On heavy wet soil... 
6-5 
6*9 
6*5 
6-2 
On good turf, not dry ...... 
12-5 
n 
n 
a 
On medium earth. 
13*6 
10*0 
ii 
a 
On hard dry turf . 
19*5 
14*8 
23. The following table contains the principal constructive details of the 
canon de 12 raye. 
Table XI. 
Weight of piece ... 
12 cwt. 1-5 lbs. 
Breech preponderance... 
1 a 42-4 „ 
Service charge . 
O n 2*2 n 
Diameter of bore. 
4-776 in. 
Diameter across the grooves . 
6-051 „ 
Length of grooves . 
67-1 /, 
Length of bore unrifled . 
4-3 „ 
Total length of bore.. 
71-5 /, 
Total length of gun over all .. 
* 81-3 „ 
Diameter at the base ring ,,,,,,......, 
.. 316*0 „ 
12-25 » 
