ORDNANCE. 



633 



IL EXTREME ENDURANCE OF PARROTT GUNS IN PROOF AND SERVICE. 





gated projectiles, to act as a punching force, 

 Mr. Holley arrives at the following conclusions : 

 " In the present state of the art of gun-making 

 a 10 or 12 -inch gun rifled so as to carry spheres 

 without injury, to fire steel and cast-iron balls 

 at short range, and light sub-calibre punching 

 bolts and shells at high velocities, and long, 

 heavy shells with large bursting charges, and 

 small propelling charges, at long range, would 

 appear to be the greatest concentration of offen- 

 sive power. But if two kinds of naval guns are 

 to be used and this would appear to be the 

 better system a smaller gun would stand 

 higher relative charges, and thus give higher 

 velocities to punching shot, and a larger gun 

 perhaps a greater calibre than 20 inches would 

 most promptly and effectually smash in a ship's 

 side, throw off her armor, and impair her sea- 

 going as well as her defensive qualities, espe- 

 cially when her armor was riddled, or shattered 

 and weakened at different points by smaller 

 and swifter projectiles." 



Experience has confirmed the justice of these 

 conclusions. In the conflict between the fleet 

 of Rear Admiral Farragut and the rebel forts 

 and armored ships in Mobile Bay in August, 

 1864, the heavy projectile from the 15-inch 

 gun of one of the monitors struck the armored 

 ram Tennessee on the side, crushing in or 

 smashing her armor, and produced some havoc 

 by means of the splinters which were thrown off 

 from the wood backing inside, while the wooden 

 gunboats, though unable to do any thing more 

 than cause her to list over by their attempts to 

 rarn her, yet pouring in their shot into her open 



Eortholes at close range from their cannon of 

 ghter calibre, disabled a large portion of her 

 crew and crippled her in some vital points. 



On the subject of the best metal for ordnance, 

 there has been hitherto great diversity of opin- 

 ion. Cast-iron is liable to the objections of 

 wanting in tenacity, elasticity, and ductility, 

 but it is harder than bronze or wrought- iron, 



* Burst in service. 



+ With Hotchkis* and Schenck's shell of 200 Ibs. 



and being homogeneous is more trustworthy and 

 uniform than wrought-iron. The advantages 

 of hollow casting and cooling from within, in 

 preventing unequal cooling and consequent ina- 

 bility to bear the unequal tension induced by 

 firing, have been already discussed in the article 

 ORDNANCE in the ANNUAL CYCLOPEDIA for 1863. 

 "Wrought-iron, though highly ductile, consid- 

 erably elastic and possessing more ultimate 

 tenacity than cast-iron, is too soft and yields too 

 much under pressure and friction, and possesses 

 the additional disadvantage of being welded up 

 from smaller pieces, and thus having no uniform 

 tenacity. Bronze, or as it is called in Europe 

 gun-metal, is too soft, not so homogeneous as 

 cast-iron, and is injuriously affected in its inti- 

 mate structure by the heat of high charges. 

 Aluminium bronze, and phosphorus alloys with 

 copper, though possessing many desirable quali- 

 ties, are too expensive for general use. An 

 alloy called sterro-metal, varying slightly in its 

 proportions when made by different manufac- 

 turers, but composed generally of 60 per cent, 

 of copper, from 42 to 46 per cent, of zi^c, 1.94 

 of iron, and from .156 to .905 of one per cent, 

 of tin, has many advantages for a gun metal, 

 being dense, hard, tenacious, elastic, and con- 

 siderably lower in price than bronze. It seems 

 very well adapted for a lining-tube for cast-iron 

 guns. For the purpose of lining-tubes, or for 

 cannon entire, there appears to be, however, no 

 other metal equal to the low steel, called also 

 homogeneous iron, and homogeneous steel, now 

 produced by casting in large masses, by Krupp's, 

 Bessemers. and other processes. Tenacious, 

 elastic, hard, and at the same time sufficiently 

 ductile and as nearly homogeneous as any largo 

 mass of metal can be, while by the present pro- 

 cesses it is produced at a moderate cost, it is pre- 

 eminently the material for all guns except the 

 very largest, and should be employed for lining 

 tubes for these. E>upp's steel guns made from 

 this low steel have been tested in every way 

 during the war, and have been found satisfactc'-v. 

 There are two or three guns made from wrought- 

 iron, which deserve special notice. TLc first 



