344s 
MINUTES OF PROCEEDINGS OF 
Table I. 
Diameter of the bore . 
Diameter across the grooves . 
Total length of bore. 
Length of grooves of the bore . 
Length of the partie r4tr6cie, answering to our 
locking groove. 
Length of chamber unrifled . 
Total length of gun, breech and swell of muzzle 
included. 
Line of metal elevation . 
Distance from the tangent sight to the trunnion 
sight . 
Distance from the axis of trunnions to that of 
piece . 
Diameter of vent. 
Number of grooves . 
Depth of grooves... 
Width of grooves at the bottom. 
Width of groove on the cylinder of the bore ...... 
Width of each bearing surface of groove. 
Width of the opposite surface. 
Angle made by the bearing surface (fianc direc- 
teur) with radius drawn to its salient angle...... 
Angle of the two sides of grooves (flancs) . 
One turn of rifling in about 26 ealibres, or. 
Windage of projectile (high gauge). 
Windage of the projections on the shot ( ailettes ) 
Service charge.. 
Weight of piece . 
Preponderance of breech.. 
86-5 mm. 
8*400 m. 
92*1 
» 
3*626 ,i 
1400* 
« 
65*120 « 
1270 
II 
50*000 a 
50 
II 
1*97 w 
130* 
II 
6*118 „ 
1600- 
IS 
62*990 a 
55' 
690* 
II 
27*165 M 
0- 
6*6 
II 
0*22 a 
6- 
6 
2*80 
II 
0*110 „ 
17* 
II 
0.669 „ 
25* 
II 
0*984 n 
7* 
II 
0*276 „ 
6- 
II 
0*197 if 
70° 
90° 
225*0 
fl 
8*858 ft. 
2*0 
H 
0*079 in. 
0*9 
II 
0*035 „ 
0*55 kil. 
11b. 3*4 oz. 
330* 
II 
6 cwt. 2 qr. 
44* 
u 
97*05 lbs. 
There is no doubt that some of the guns first made in 1857 exhibited 
considerable signs of wear after 200 rounds,—the fact is admitted: it is 
asserted that by subsequent improvement, more especially in the centering of 
the projectiles, they have attained as many as 2500 rounds without perceptible 
injury. 
The annexed diagram shows the actual form of the grooves, and the 
manner in which they are traced. 
Fig. 1. 
AB = radius of the bore drawn to the angle of a groove =z 1*703 
inches, 
BII == driving side of the groove drawn so that IIBC = 70°, 
III = bottom of groove described with radius 1*703 + 0*110 = T813* 
and 0*669 wide, 
IK = loading side of groove drawn through I so that KLM = 90°, 
i 
