449 
PRINCIPLES OE GUNNERY. 
RIFLED ORDNANCE. 
BY 
MAJOR J. SLADEN, R.A. 
PROFESSOR OP ARTILLERY, R.M. ACADEMY, WOOLWICH. 
{Continued from p. 432.) 
CHAPTER IX. 
The Penetration op Projectiles. 
Energy absorbed in Penetration.—Energy absorbed in Perforation.—Method of estimating tbe 
Resistance to tbe Projectile.—Formulae for calculating Perforation of unbacked wrought- 
iron Plates.—Materials used for Armour-Plates: Cast-iron, Wrought-iron, Steel.—Compound 
Plates.—The form of Head of Projectile.—Energy required to Perforate a Plate obliquely.— 
Material of Projectile.—Armour Plates with intervals between them.—The Effect of Common 
Shell on Armour-Plates.—The Effect of Palliser Shell with wrought-iron points.—Wood.— 
Earth.—Masonry.—Concrete. 
No accurate experiments have as yet been carried out in order to 
determine the coefficients of resistance for the different materials of 
projectiles and plates, so that it is difficult to study the subject advan¬ 
tageously in a rigid mathematical way ; but practically the amount of 
penetration, whether for iron or steel plates, or masonry, or earth, 
has been determined by actual experiment. Various empirical laws 
have, from time to time, been brought forward, which have sufficed to 
give approximate results for experimental purposes, but they have not 
stood the test of any general application. There are, indeed, so many 
varying conditions which take place in actual experiment that it is 
almost impossible to apply practically strictly analytical investigations 
—for instance, the varying qualities of resistance both in projectiles 
and targets, the variation in shape of the projectile on impact, the 
possibility of the projectile breaking up, and the amount of heat 
developed on impact. Such investigations may be studied in Didioffis 
“Traite de Balistique,” p. 285 et seq.; but in the following pages the 
subject will be considered in a more experimental way, and the pene¬ 
trative effect of projectiles against iron, steel, wood, earth, and masonry 
will be considered in detail. Generally speaking, the penetrative 
effect depends on the shape and material of the projectile, on its 
energy, and diameter, and the direction with which it strikes the 
target. 
It is evident that if a projectile has not sufficient energy to perforate Energy 
a resisting medium, it will penetrate a certain distance until its energy penetratfo? 
has been absorbed by the resistance. 
58 
