11*2 
MINUTES OF PROCEEDINGS OF 
passage will always force its way down to its own level. If an outlet, there¬ 
fore, be allowed for the hot air from the bottom of the stove, a continual 
current ought to be established. The outlet, however, w r as led into a flue, 
so as further to increase the draught. 
Trom some cause or other a sufficient current was not established until the 
flue w^as increased by a wooden continuation ; but when this was added it was 
found, when at work, that the draught was sufficient to draw so great a 
quantity of air through the stove as to bring down the temperature. The 
temperature could be raised by diminishing the opening by wdiich the external 
air was admitted to the steam-pipes to become heated. The best plan would 
be to bring the outlet into communication with some arrangement which wmuld 
produce a partial vacuum, such as a steam jet; for a vacuum is a well-known 
method of drying. Thus the temperature might be lowered in the stove with 
advantage to the drying of the powder—a low temperature and sufficient 
current of air being the best plan of drying. 
This paper may be concluded by giving a few r samples of powxler fired in 
the 85-ton gun, by way of experiment, to see what powder is likely to be 
most suitable. The following rounds were fired with 110 lbs. of powder and 
700 lbs. projectile. 
1 # 
Description of powder. 
Density. 
I 
Fired in 35 
gun. 
-ton 
Fired 
in 8-in. gun. 
.a* 1 
J’J 
S £ ; 
Pressures. 
No. of 
round. 
Muzzle 
velocity. 
Pressures. 
A. 
1 
1 c. 
A. 
B. 
C. 
W.A. pebble, 22. 4. 73 ... 
1-79 
1345 
23*2 
16-6 
556 
1468 
17-9 
17-1 
16-7 
// inch cubes, 23. 4. 73 
1-79 
1328 j 
21-8 
19-2 
564 
1431 
18-2 
17-3 
16-4 
a lot 1970 . 
1-78 
1359 
23-4 
20-7 
618 
1486 
19-5 
19-7 
18-5 
' « inch cubes. 
1-82 
926 
25 
broke 
800 
750 
— 
— 
— 
II II II . 
1-77 
. not fired 
94 
1535 
21*7 
20-5 
18-8 
II II II ... .. 
1-75 
1352 
24-1 
19-6 
104 
1485 
17-0 
17-3 
15-7 
n a a . 
1*73 
1368 
24-8 
22-3 
105 
1504 
18-4 
18-8 
18-1 
n l^-inch cubes . 
1-77 
1334 
20-7 
18*5 
95 
1469 
15-7 
15 0 
15-5 
// // II . 
1-75 
1311 
241 
16-0 
96 
1425 
; i3-2 
13-2 
12-6 
II II 11 . 
1-73 
1334 
22-5 
19-4 
98 
1456 
; 14-6 
14-7 
14-2 
u 2-inch cubes . 
1-79 
1095 
7-5 
6-8 
— 
— 
— 
— 
— 
II II II . 
1-77 
1262 
18-0 
15-1 
99 
1429 
13-5 
13-9 
— 
n n n .. • • 
1-75 
1239 
13-4 
11-3 
100 
1367 
1 9-9 
9-9 
10-2 
II II II . 
173 
1241 
13-6 
11-7 
101 
1371 
10-8 
10-6 
10-8 
II. and S. inch cubes, A ... 
1-82 
1355 
19*8 
18-2 
736 
1440 
12-8 
12-9 
13-3 
„ ,/ B ... 
1-82 
1376 
' 24-0 
- 22-4 
738 
1480 
11-03 
11-7 
11-5 
„ „ C ... 
1-75 
1385 i 
23-8 
19-8 
1192 
1483 
17-7 
18-6 
18-2 
_ 
It is manifest from these experiments that the rate of combustion of gun¬ 
powder is completely under control, and is a mere matter of manufacturing 
detail. The various causes which conduce to the attainment of any desired 
result are not, however, so readily determined; for it will be observed that, true 
to themselves in their apparent inconsistencies, these samples in many cases 
seem to arrange themselves in exactly the opposite order to ivhat might have 
been expected. The effect of size of grain is well known, and the theory of 
each grain burning from surface to centre has often been advanced, and therefore 
calls for no special remark. It should, however, also be understood that 
with this theory must be combined a consideration not only of the density 
