60 ANNUAL OF SCIENTIFIC DISCOVERY. 



lower one 6i inches. One-half of the target was backed with teak- 

 wood planking 10 inches in thickness, and the wood was backed with 

 inside plates of iron 2^ inches in thickness. The other half of the 

 target had. the outside plates bolted to strong vertical iron ribs, but 

 had no teak backing or inner skin plates. Six feet square of the 

 target, therefore, were formed of 10, 0, and 8 inches in thickness of 

 iron and 10 inches of teak. The quality of the plates was superior 

 to any ever tested in a target. The firing was at a distance of 

 200 yards ; and the guns tried consisted of the old smooth 68-pounder, 

 Armstrong's 110-pounder service gun (with special steel shot cut 

 down at the base to reduce them to 65 Ibs. weight), Armstrong's 

 300-pounder muzzle-loading rifled shunt gun, Whitworth's muzzle- 

 loading 150-pounder or 7-4nch gun, and Thomas's 9-inch or 300- 

 pounder rifled muzzle-loading gun. Both these latter were made by 

 Colonel Anderson, at Woolwich, on the built-up coil principle adopted 

 by Armstrong; both were admirable specimens of workmanship, 

 though, before the experiments commenced, Whitworth's gun was 

 found to have a crack or flaw in the centre steel tube round which the 

 coils of wrought-iron are wound and welded in the course of manu- 

 facture. This defect prevented its being used in the course of the 

 experiments except for one discharge with a line-shell. Thomas's gun 

 was an enormous piece of ordnance, nearly 18 feet long, weighing 1G 

 tons, and with a thickness of 1 7 inches of metal around the powder 

 chamber at the breech. Though nominally a 300-pounder, this gun is 

 claimed to be capable of throwing projectiles of various forms and 

 weight, from 250 Ibs. up to 410 Ibs. Armstrong's 300-pounder weighs 

 less than 1 2 tons. 



The first shots, three in number, were fired from the old smooth-bore 

 68-pounder, with the usual service charge of 16 Ibs. of powder; these 

 were directed against the 5^, 6-J- and 7^-inch plates, and were immedi- 

 ately followed by three shots from Armstrong's 110-pouncler, loaded 

 with special steel projectiles weighing 65 Ibs., and fired with the same 

 service charge as the smooth-bore 68-pounder. Where the 68-pounder 

 had struck, the indentation varied from 2 inches to 3 inches in depth ; 

 where the steel shot of Armstrong's had hit, the mark Avas in one case 

 deeper, and the plate showed a perceptible' crack about 8 inches long, 

 though apparently of very trifling depth. But the most careful exam- 

 ination failed to discover any mark on the back of the target to show 

 that it had been hit at all. 



The next shot was fired from Armstrong's 300-pounder, loaded with 

 a conical steel shot of 296 Ibs. weight, and fired with 45 Ibs. of powder. 

 This tremendous missile struck, with a velocity of 1,298 feet per sec- 

 ond, full upon the centre of the 7^-inch plate, where it was backed, 

 driving in a circular piece of iron 10 inches in diameter quite through 

 the plate, bending in the whole plate itself to the depth of an inch and 

 a half, and buckling its ends outwards more than an inch. The mas- 

 si v<> wrought iron girder which crossed the whole back of the target 

 horizontally was bent out and broken in several places, as were also 

 the inner ribs ; the 2^-inch skin was bulged and cracked, the rivet 

 beads loosened, and many knocked off altogether. The examination 

 showed that the target had received a most serious shake, though, from 

 the wonderfully good quality of the iron, there was little of actual frac- 



