PRINCIPLES OF GUNNERY. 
55 
Table showing JVorh Tone per pound of "Powder in a Gun. 
Number of 
volumes of 
expansion in 
the bore. 
5-0 
5*1 
5’2 
5*3 
5-4 
5-5 
5-6 
57 
5- 8 
6"9 
6 - 0 
6-1 
6-2 
6"3 
6*4 
6o 
6 - 6 
67 
6-8 
6- 9 
7- 0 
7-1 
7-2 
7-3 
7-4 
7o 
Total work the powder 
is capable of realising 
per pound burnt, in 
ft. tons. 
83- 53 
84- 25 
84-95 
85*64 
86-31 
86- 96 
87- 60 
88 - 22 
88- 83 
89- 43 
90- 02 
90- 59 
91- 14 
91- 69 
92- 23 
92- 76 
93- 28 
93- 78 
94- 28 
94- 77 
95- 25 
95- 72 
96- 18 
96- 63 
97- 08 
97-52 
diff. 
72 
70 
69 
67 
65 
64 
62 
61 
60 
59 
57 
55 
65 
54 
53 
52 
50 
50 
49 
48 
47 
46 
45 
45 
44 
44 
Number of 
volumes of 
expansion in 
the bore. 
7-6 
7-7 
7-8 
7- 9 
8 - 0 
8-1 
8-2 
8-3 
8-4 
8-5 
8-6 
8-7 
8-8 
8- 9 
9- 0 
9-1 
9-2 
9-3 
9-4 
9"5 
9-6 
97 
9-8 
9-9 
10-0 
Total work the powder 
is capable of realising 
per pound burnt, in 
ft. tons. 
97- 96 
98- 39 
98- 81 
99- 23 
99-64 
100-04 
100-44 
100- 84 
101- 23 
101-62 
102 - 00 
102-38 
102- 75 
103- 12 
103-48 
103- 84 
104- 19 
104-54 
104- 89 
105- 23 
105-67 
105- 90 
106- 23 
106-55 
106-87 
diff. 
43 
42 
42 
41 
40 
40 
40 
39 
39 
38 
38 
37 
37 
36 
36 
35 
35 
35 
34 
34 
33 
33 
32 
32 
By means of the above table, the maximum work that can possibly 
be obtained in any gun by a given charge of powder may be calculated. 
Example. —What is the maximum work that can possibly be done 
by 50lbs. of P. powder in the 9-in. M.L. gun? (The length of the 
bore is 125 ins.) 
Volume of bore — — x 81 x 125 cub. ins., 
4 
volume of charge (50 lbs.) = 50 x 27*7 cub. ins.; 
so that the number of the volumes of expansion of the powder charge 
contained in the bore of the gun are 
7T x 81 x 125 ___ 
200 x 27-7 ~ ~ ° * 
From the table, then (by proportional parts), it will be seen that 
the maximum work capable of being performed by the charge of 
50 lbs. of P. powder in the 9-in. M.L. gun 
= 50 x 88*46 = 4423 ft. tons. 
But the actual muzzle velocity of the 9-in. gun, with a 250-lb. pro¬ 
jectile and 50 lbs. of P. powder, is about 1420 f.s.; so that the muzzle 
energy communicated to the projectile is 
250 x (1420) 3 
4480 x 82-2 
= 3494 ft. tons. 
