432 REPORT — 1806. 



As before stated, it is proved that a " work " of about 58 foot-tons per inch, 

 of shot's circumference will just penetrate a 5-5-inc]i plate and 25 inches of 

 wood ; and we may assume that it will require a force of 4-i foot- tons per inch 

 to penetrate the same ship if the plates be 4'5 inches. 



In order to demonstrate how this knowledge may prove of advantage, let 

 us suppose the following case. 



H.M.S. ' Favourite ' is a wooden ship of about 22 inches thickness, pro- 

 tected by 4-5-inch plates, and armed with 7-inch M L rifled guns throwing 

 solid elongated steel shot of 115 lbs. weight and 6-D2 inches diameter, with 

 a charge of 22 lbs. 



Suppose this ship meets an enemy's vessel of the same thickness, but pro- 

 tected by 5-5-inch plates, and armed with 11-inch smooth-bore guns throw- 

 ing solid spherical steel shot of 189 lbs. weight and 10-85 inches diameter, 

 with a charge of 20 lbs. 



To all appearance the enemy's vessel is much the stronger of the two. 

 We find, however, that at 500 yards the'll-inch projectiles would strike with 

 a " work " of only 31 foot-tons per inch of shot's circumference, and conse- 

 quently would fail to penetrate the ' Favourite,' wliich requires a force of 

 about 41 foot-tons ; while, on the other hand, the projectiles from the rifled 

 guns of the latter ship would at 500 yards strike with a " work " of about 

 65 foot-tons per inch of sliot's circumference, which would be amply suflicient 

 to penetrate, even with steel or chilled shells, the side of a ship of 22 inches 

 thickness, protected by 5-5-tiich plates. 



It may, however, be urged that, although the 11-inch shot could not pene- 

 trate, they would have great battering effect. But it is submitted that the 

 projectile which can perforate the side of an enemy's ship and disable her 

 crew, machinery, or magazine, is decidedly to be preferred. Battering is all 

 very well ia theory, but we know ■nliat a battering the ' Tennessee ' stood 

 without being much injured ; and if the ' Favourite ' should ever liappen to 

 fall in with an enemy's wooden frigate protected by S-S-inch plates and 

 armed with big smooth-bore guns, she will most likely be able to dispose of 

 lier in a satisfactory maimer. 



If we examine the experiments carried out against the ' Lord Warden ' 

 target, it appears that the target was completely penetrated by a force repre- 

 sented by 92 foot-tons per inch of shot's circumference, while 88 tons per 

 inch failed to penetrate, although it evidently very nearly did so. We may 

 assume from this that a force of about 90 tons per inch is just capable of 

 piercing the ' Lord Warden.' 



Now this ship consists of — 



1st. A 4*5-inch armour plate. 

 2nd. 8| inches of wood backing. 

 3rd. A 1-5-inch iron plate. 

 4th. 20| inches of wood. 



And if we assume the force required to i)enetrate the iron part of it to vaiy 

 as the squares of the thicknesses of the plates, we shall have 28 tons for the 

 4-5-inch plate, and 3-1 to2is per inch for the 1-5-incli plate, thus lea^^ng 58 

 tons^for the backing and wood. This seems a large amount, but we must re- 

 member that the target is very thick. We have, unfortunately, no data upon 

 which we can depend relative to the penetration of backing and the eft'ect of 

 dividing it by vertical iron plates of less thickness than the principal armour 

 plate. It is probable, however, that the strength of the ' Loi-d Warden ' 

 would have been increased had the Ig-inch inner plate been differently dis- 



