SHORT NOTES ON PROFESSIONAL SUBJECTS. 
12 ? 
The velocities and pressures given by these powders are shewn in the following 
table:— 
Table shewing the velocity and maximum pressure per square inch given by 
four different descriptions of powder, fired with shot of 180 lbs. in the 8-inch gun, 
Exp], No. 288. 
Nature of powder. 
Charge. 
Muzzle 
velocity. 
Maximum 
pressure. 
lbs. 
ft. 
tons. 
R.L.Gr.... 
30 
1324 
29-8 
Russian prismatic ... 
32 
1366 
20-5 
Service pellet . 
30 
1338 
17-4 
Pebble, No. 5 . 
35 
1374 
15-4 
The first example given above represents R.L.Gr. powder of 1*67 density; the 
committee have found, however, that there is a very great want of uniformity in 
the service R.L.Gr. and L.G\ powders at present in store, as evidenced by differences 
in the densities which range between 1*60 and 1*78. 
A powder having a density of 1*745 has also been tried; it gave, with a 30lbs. 
charge, a velocity of 1350 ft., and indicated a maximum pressure of 23 tons per 
square inch. 
A careful consideration of the results hitherto obtained with the form of powder 
termed “pebble,” and the circumstance that the production of such a powder 
involves little departure from the existing system of manufacture, have led the 
committee to decide that they are justified in recommending the provisional 
adoption (and the manufacture to such an extent as may be at present required 
for the supply of all heavy guns of 7-inch calibre and upwards) of a “pebble” 
powder made according to the following specification:— 
“The powder to have a density of 1*80 (the limits of manufacture being 1*78 
and 1*82), and to be produced by breaking up “press-cake” of the specified density 
into lumps, which are retained between sieves of J and •§• in. mesh respectively. 
The lumps to be afterwards submitted to the ordinary processes.” 
The committee consider that, in the event of the provisional introduction of 
“ pebble ” powder, steps should be at once taken to ascertain the charges of this 
powder required to obtain velocities equal to the standard velocities of the several 
heavy guns. 
The committee have already reported that the employment of the description of 
powder now recommended will not entail any alterations in the dimensions of the 
present pattern metal cases. 
In confining themselves to a recommendation that the charges of the new 
powder for heavy guns should be proportioned to give velocities equal to those 
obtained with R.L.Gr., the committee think it right to point out that, in addition 
to the reduction in maximum pressure Obtained by the use of “ pebble ” powder, 
or such powder of similar properties as may be finally adopted, there is a proba* 
bility that another important advantage will be secured—namely, the attainment 
with safety of a considerable increment in velocity with heavy guns, whereby a 
material increase will be effected in the power of our armament. 
It is anticipated that definite and conclusive information on these important 
points will be furnished by the experiments with the 10-inch gun which are now 
in progress. 
