MECHANICS AND USEFUL ARTS. Ill 



extending from the muzzle nearly to the trunnions ; 3cl, the breech 

 coil, consisting of 3 coils in alternate directions, welded to- 

 gether, with a trunnion welded on, the whole piece shrunk on 

 over the breech of the barrel, and lapping over the front coil ; 

 4th, the cascable. It is considered by the present authorities that 

 the diminution in number of parts leaves the gun less liable to 

 injury by accident, and less dependent upon perfection in manu- 

 facture, and that practically an equal amount of strength is 

 obtained ; while it is held that a fil)rous iron is to be preferred, as 

 moi'e workable for coils, and as giving out its greatest strain over 

 a greater distance than the best Yorkshire iron, which, while 

 strong statically, is considered not to yield so far before fracture. 

 It is stated that this change has diminished the cost of production 

 by 35 or 40 per cent. 



"The heaviest projectile thrown by any gun in the service, 

 prior to 1854, was the 200-lb. shell of the 13-inch mortar. 



'* The larofest Armstronof ofun hitherto constructed is an ex- 

 perimental one, which has a calibre of 13.1 inch, weighs 23 tons, 

 and throws a shell of 600 lbs. 



" It is intended that future 12-inch guns shall have a weight of 

 25 tons. 



" The 11-inch gun lately constructed weighs 23 tons, and the 

 weight of the several parts are as follows : The steel barrel, 5 tons 

 5 cwt. in the rough, 2 tons 16 cwt. finished ; the muzzle-coil, 2 tons 

 15 cwt. in the rough, 1 ton 16 cwt. finished ; the trunnion and 

 breech coil, 22 tons 6 cwt. in the rough, 17 tons 17 cwt. finished ; 

 the cascable 14 cwt. in the rough, 11 cwt. finished. 



'* Two guns of Mr. Whitworth's, of 9-inch calibre, and weighing 

 15 tons, are about to be delivered for trial. 



"Prior to the mechanical improvements which have led up to 

 the present rifled guns, the greatest distance to which a projectile 

 was ever thrown from a smooth-bore gun was not much over 

 6,000 yards, and the limit of bombarding range at high elevations, 

 with the 13-inch mortar was 4,500 yards. With the modern 

 ordnance, projectiles have been thrown with greater precision to 

 a range exceeding 10,000 yards; the guns of the service make 

 good practice at 6,500 yards, — in fact, much better practice than 

 was formerly attainable at 3,000 yards. 



" At 1,000 yards the mean error of range of round shot from 

 smooth bores may be taken as 43 yards, and that of rifled shot 

 19 yards ; the mean error of direction (referred to the mean 

 direction of all the shot) with round shot ma}'' be taken as 4.1 

 yards, and with rifled shot as 0.8 yard. At 2,000 yards the mean 

 error of range of round shot may be taken as 60 yards, and that 

 of rifled shot 21 yards ; the mean error of direction with round 

 shot 10 yards, and with rifled shot 21 yards. In other words, — 

 the accuracy being inversely as the products of the errors, — the 

 rifled gun is in one case more than 11 times, and in the other 

 more than 13 times, as accurate as the smooth boix3." 





