ON RIFLED GUNS FOR ATTACKING ARMOUR-PLATE DEFENCES. 105 
Three conditions may be laid down as necessary to enable artillery to 
attack successfully armour-plate defences: 1st, the projectile must be of the 
proper form; 2nd, of the proper material; and 3rd, be propelled from a gun 
able to give it the necessary velocity. The artillery of the Ordnance Select 
Committee failed because they utterly neglected the first two conditions, and 
had recourse to the brute force of the smooth-bore for the third. The ex- 
pression accepted as representing the penetrating power of shot was “ velo- 
city squared, multiplied by weight;” but the form of the shot and the mate- 
rial were conditions altogether omitted from the expression ; and the import- 
ance of the omission will be obvious at once if we take an analogous case, say 
that of a punching-machine employed to perforate wrought-iron plates. What 
would be the result if the punch itself, which is made of suitable shape and 
material, were removed, and a round-headed poker, of brittle cast iron or soft 
wrought iron, were substituted in its place? The great importance of suf- 
ficient velocity is conceded—it is a sine-qud-non condition ; but has there not 
been great misconception in supposing that the old smooth-bore gives a 
greater initial velocity than the rifled gun? The results obtained will show 
how thisis. The average initial velocity of the 68-pounder is, in round num- 
bers, 1600 feet per second with a charge of powder one-fourth the weight of 
the shot, the length of the shot being of course one calibre. Sir William 
Armstrong stated that with a charge of powder one-fourth the weight of the 
shot, he obtained with his rifled gun an initial velocity of 1740 feet per second: 
he did not state the length of his projectile. Mr. Whitworth, with a projec- 
tile one and a half calibre long, obtains an initial velocity of 1900 feet per 
second ; and with a projectile one calibre long, like that of the smooth-bore, an 
initial velocity of 2200 feet per second, being greater than that of the smooth- 
bore in the proportion of 22 to 16. The reason why, under nearly similar con- 
ditions as to charge and length of projectile, the rifled gun had an initial velocity 
so greatly superior to that of the smooth must be ascribed to the action of the 
first condition I ventured to lay down as necessary. The rifled projectile, as 
compared with the spherical, has a form which is better adapted for flight, 
and fits more accurately the bore of the gun, so that the gases of explosion 
exert a greater pressure upon it while propelling it through the barrel. In 
practice the initial velocity of the rifled projectile is lower than that of the 
smooth-bore, because with the rifled gun the charge of powder used is much 
less, while the projectile is much longer and heavier, and has a greater vis 
imertie to be overcome at starting than that of the smooth-bore. If very 
large charges be used with the rifled guns, and long projectiles, with the view 
of obtaining increased velocity, the strain becomes too great for the guns 
to bear; but if rifled guns are fired with charges so low that they are not 
made to perform half the work they ought to do, then, though the defects of 
weak construction may not be made patent by the gun being destroyed, they 
are very plainly manifested by the weak results of their projectiles fired 
against armour-plates. It is proved by well-known results that the con- 
structors of the 110-pounder rifled gun, now adopted in the service, do not 
dare to make the gun perform its full work ; but, on the contrary, they find 
_ themselves forced gradually to reduce their charges, until they are well beaten 
_ by the old smooth-bore they undertook to supersede. The only conclusion 
that can be drawn from this fact is, that the gun is weak in construction, 
and the projectile used with it is defective in principle. 
_ The power of the smooth-bore, with its large windage, to fire large charges, 
and thereby obtain great velocities, has procured it mary advocates ; but Mr. 
Whitworth’s experiments have shown that if length of projectile be given up, 
