264 
POPULAR SCIENCE REVIEW, 
Resistance of Armour Plates. — From a paper read by Mr. Fairbairn at 
the Institute of Naval Architects, in March, but only recently printed, we 
extract the following table to show the close accordance of a formula for 
the penetration of plates, by steel flat-ended shot, deduced more than two 
years ago, from experiments with a rifle, and the more recent experiments 
of Mr. Whitworth ; the table is also interesting as an exact and reliable 
record of the best artillery practice against plates by the English 
Government : — ■ 
Description of 
Gun. 
Weight 
of Shot in 
pounds. 
Charge of 
powder in 
pounds. 
Velocity 
of shot in 
feet per 
sec. 
Semi-dia- 
meter of 
shot in 
inches. 
Maximum 
thickness of 
penetration 
by formula 
in inches. 
Thickness 
actually 
penetrated 
in inches. 
Wall pie 
ce Rifle . 
0-34 
1141 
0-435 
0-81 
0-81 
Whitworth 12 Pr. 
12-06 
1-875 
1202 
1-5 
2-72 
2-50 
99 
12 Pr. 
12-16 
1-750 
1157 
1-5 
2-63 
2-005 
99 
70 Pr. 
68-50 
12-00 
1276 
2-75 
5-09 
4-00c 
99 
120 Pr. 
129-00 
23-00 
1278 
3-5 
6-20 
4-50 d 
99 
120 Pr. 
130-00 
25-00 
1268 
3-5 
6T7 
4‘50e 
99 
120 Pr. 
130-00 
25-00 
3-5 
6-17 
5-50 
b. The shell penetrated 12 inches of wood backing and buried itself 
in a sandbank. 
c. Penetrated 13 inches of Wood backing and cracked a 2-inch plate 
in the rear. 
d. Penetrated 20 inches of wood backing and fractured iron skin. 
e. Shell burst whilst penetrating wood backing. 
The same formula with a variation of a single constant applies equally 
well to the penetration of plates by cast-iron shot. 
Corrosion of Armour Plates. — The Royal Gale having been docked at 
Key ham, has revealed a new and insidious danger besetting our iron- 
cased fleet. The lowest tier of her armour plates is all more or less 
honeycombed, and partially destroyed by galvanic action arising from 
contact with the copper sheathing below. The holes vary in depth from 
4 to f inch. She has not been more than five months in the water. 
Plates of vitreous sheathing are to be applied to prevent further injury. 
Centrifugal Pumps. — Careful experiments on one of Appold’s centrifugal 
pumps have been made by Mr. Anderson, at Wexford. These were on a 
scale and under circumstances which render the results more reliable than 
in most previous experiments. With from 44 to 60 indicated horse- 
power, 1,600 to 2,200 cubic feet of water were lifted from 6 to 10 feet 
high per minute. Averaging the results and deducting one-sixth of the 
power expended as engine friction, the efficiency of the pumps appears to 
be 67 per cent. 
The Armstrong Cun. — A new gun of Sir William Armstrong’s, "weighing 
22 tons, and 13*3 inches calibre, has been successfully tested at Shoebury- 
ness. The thickness of the walls at the breech is 20 inches, the outside 
diameter being 55 inches. The total length is 15 feet. The rifling is on 
