ON RIFLED GUNS FOR ATTACKING ARMOUR-PLATE DEFENCES. 107 
Gun. Charge, Velocity. 
ABeputiler: 2. 13s. ess et ee 16 lbs. | Initial, 1600 feet per second. 
Whitworth 70-pounder............sse08 12 lbs. | Initial, 1350 feet per second. 
Whitworth 120-pounder ..,............ 25 Ibs. | Terminal at 600 yards, 1260 feet per 
second. 
Armstrong 110-pounder ............s00+ 14 lbs. | Initial, 1210 feet per second. 
With regard to initial velocity, therefore, the order of the guns may be taken 
to be, with the charges used—1st, 68-pounder ; 2nd, Whitworth; 3rd, Arm- 
strong. It is worthy of notice, however, that the velocity of the Whitworth 
120-pounder after traversing 600 yards (a good fighting-range) was found 
actually to be 1260 feet, whereas the initial velocity of the Armstrong is only 
1210 feet. 
The total results in respect of penetration proving themselves to be so 
decidedly in favour of Whitworth, who combines with condition three, viz. 
sufficient velocity, conditions one and two, proper form and material of pro- 
jectile, it follows that his must be the best compromise. The slight inferiority 
in initial velocity of his rifled gun, as compared with the smooth-bore, is 
more than compensated for by employing a projectile of proper form and 
material, as is shown by the penetration being through-and-through both 
5-inch plate and backing in the case of the Whitworth, while it is barely 
half-through the armour-plate in the case of the smooth-bore, and not half- 
through in the case of the Armstrong gun. 
- The form of projectile employed by Mr. Whitworth for penetrating armour- 
plates is like the one now before the Section. It has a flattened front, the centre 
being slightly rounded ; the middle part of the projectile is rifled hexagonally, 
like the bore of the gun; the front and rear of the projectile are made of the 
requisite taper to allow the air displaced in front to close in readily behind— 
a form which gives a great increase of velocity as compared with the form 
parallel throughout, as I endeavoured to explain to this Section in a paper I 
had the honour of reading at its meeting last year. 
The material of which the projectile is composed is what is termed homo- 
geneous metal, combining the toughness of copper with the hardness of steel : 
it is made hard enough to penetrate the wrought-iron plate, but not so hard 
as to be brittle and break up when the projectile strikes against its sur- 
face. The advantage of the flat front as compared with a pointed front is 
apparent, when it is considered that when the flat front strikes a plate, 
the whole resistance it meets with is that offered by the area of the plate 
covered by the flat front in a direction in line with the axis of the impinging 
projectile : it consequently punches out a clean hole, with a sudden impact. 
In the case of a pointed shot, as soon as the point begins to penetrate, the 
inclined sides begin to push aside the particles of the plate in a lateral direc- 
tion, and an accumulating lateral resistance is offered by every part of the 
plate whose particles are disturbed; the passage of the shot is thereby gra- 
dually retarded, if not altogether arrested. It has been thought that the 
flat-fronted projectile will glance from the surface of an inclined plate like a 
round projectile: this is not found to be the case, as is proved by the plate 
now shown to the Section, which was completely penetrated by a flat-fronted 
_ projectile when inclined at an angle of 37° to the perpendicular. 
' The Whitworth penetration-shell, whose destructive power was shown by 
its penetrating and shattering the ‘ Warrior’ target at Shoeburyness, has the 
same form outwardly, and is made of the same material (homogeneous metal) 
as the flat-fronted solid projectile which has already been described. A 
