PENETRATION OF IRON PLATES BY STEEL SHOT. 403 



Report on various Experiments carried out by Captain W. H. Noble, 

 R.A., under the direction of the Ordnance Select Committee, rela- 

 tive to the Penetration of Iron Armour Plates by Steel shot, to 

 which is added a Memorandum on the Penetration of Iron-Clad 

 Ships by Steel and other Projectiles. 



[A communication ordered to be printed among the Eeports.] 



In 1862 the Special Committee on Iron proposed a series of experiments for 

 the purpose of ascertaining whether the penetration of projectiles into iron 

 was proportional to their vis viva. 



Tlie guns proposed for use were the 68-pounder smooth-bore, and 7-inch 

 B L ritied gun, and the necessary charges were determined by the Ordnance 

 Select Committee with the aid of Navez's Electroballistic Apparatus. 



A few experiments were subsequently made ; but the results were not to 

 be relied on, as the projectiles used were cast iron and broke up on impact. 

 This subject was revived in 1864 by the Ordnance Select Committee, and a 

 series of expeiiments were authorized for the purpose of determining the fol- 

 lowing points : — - 



First. To determine the relative penetrating effects of two shots on an 

 iron plate, provided they strike with the same "work"*, notwithstanding 

 that the one may be heavy with a low velocity, and the other light with a 

 high velocity. 



Secondly. To determine the relative resistances of a plate to penetration by 

 two shots of similar form of head, and striking with " work " proportional 

 to their respective diameters. 



An example of the first point may be stated as follows :— The 10"-5 

 wrought-iron gun of 12 tons is fired at an iron plate with a charge of 50 lbs., 

 and spherical steel shot of 168| lbs., the velocity at 200 yards being 1570 

 feet, and consequent "work" 2898 foot-tonsf. 



The same gun is fired in its rifled state at a similar plate, with a charge of 

 40 lbs., and hemispherical-headed steel elongated shot of 300 lbs., the velo- 

 city at 200 yards being 1180 feet, and consequent "work" 2898 foot-tons. 



Will the penetration + be the same in both cases? 



The following case will serve to illustrate the second point : — 



The 100-pounder smooth-bore gun of 6| tons is fired at an iron plate 

 with a charge of 15-4 lbs., and siAerical steel shot of 104-1 lbs. weight and 

 8-87 inches diameter, the velocity at 100 yards being 1254 feet, and con- 

 sequent '-work" 1135 foot-tons. 



The 7-inch M L rifled gun of 130 cwt. is fired at a similar plate, with a 

 charge of 13-5 lbs., and elongated hemispherical-headed steel shot of 100-3 lbs, 

 weight and 6-92 inches diameter, the velocity at 100 yards being 1129 feet, 

 and consequent "work " 886 foot-tons. Will the penetrationj be the same iu 

 both cases, the vis viva beiag proportional to the respective diameters, or as 

 8-87 to 6-92 ? 



-g- , where W= weight of shot, 



i;= velocity on impact, 

 ff = the accelerating force of gi-avity. 

 t Vis viva has been given in foot-tons instead of foot-pounds, in consequence of the 

 number of figures required to express the latter. 



J Jiy penetration is meant mttuvA perforation through the plate, or the power of passing 

 through the plate. In the case of penetration into iron plates the term " indent " has been 

 used. 



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