SHOUT NOTES ON PUOEESSIONAL SUBJECTS. 
33 
31. Pellet powder. “ Pellet powder ” has been provisionally approved for 
charges of guns over 12 tons weight. 
The powder, in place of being made into press cake and then granulated, which 
involves the formation of a quantity of smaller grains and particles, is pressed into 
cylindrical pellets about *5" long •75" diameter, perforated at one end to about the 
centre. 
The object is to obtain a comparatively slow burning powder having a large and 
uniform grain or pellet. 
32. Resistance oe iron armour plates. An experiment was carried out 
at Shoeburyness, on 29th July, 1867, for the purpose of ascertaining the resistance 
of wrought-iron plates backed by iron, or built up armour plates, in comparison 
with solid plates. 
The targets were supplied by Messrs Cammell of Sheffield, for this experiment, 
and consisted as follows :— 
No. 1. Two 3J-in. plates riveted together, making a total thickness of 7 in. 
The plate being 5 ft. X 4 ft. 
No. 2. Three 2^-in. plates riveted together, making a total thickness of 7 in. 
The plate being 5 ft. X 4 ft. 
The iron of which these plates were composed was identical with that used in 
No. 7 solid plate. 
Both targets were firmly secured to wooden supports, but unbacked. 
They were fired at with Palliser shot from the 7-in. rifled M.L. gun of 7 tons. 
Range 70 yards. 
The following conclusions may be drawn from these results, taken in conjunction 
with those of previous experiments:— 
(1) With the above gun and projectile at this distance, it would require about 
15’5lbs. of powder to perforate a solid 7-in. plate. The “energy” in the shot 
being about 61 foot tons per inch of its circumference. 
(2) It requires about 14 lbs. of powder to perforate a 7-in. compound plate 
made up of two separate thicknesses of 3-|-in. riveted together, the “ energy ” in 
the shot being about 57 foot tons per inch of its circumference. 
(3) It requires about 13 lbs. of powder to perforate a 7-in. compound plate 
made up of three separate thicknesses of 2-J-in., the “ energy” in the shot being 
about 5 2 foot tons per inch of its circumference. 
These results shew that plates thus built up in thick layers bolted together, 
afford a very large amount of resistance, although they are not quite equal to a 
solid plate. 
It is probable that the resistance of three 5-in. plates riveted together, would 
more than equal that of a solid 13-in. plate, while they would be decidedly cheaper. 
By calculation, it would require 16’94 foot tons per inch of shot’s circumference 
to perforate a 3^ inch plate; and 7*53 foot tons to perforate a 2^ inch plate, 
provided the plates were taken individually. 
33. Proportional military models.* —These are blocks of boxwood 
chiefly rectangular, representing companies of infantry, squadrons of cavalry, guns, 
* Designed by Capt. W. A. Eoss, E.A., and can be obtained at E.A. Institution, Woolwich. 
