THE KGYAL ARTILLERY INSTITUTION. 
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machine could easily be constructed which would cut them all in one 
operation. 
But how about chilled projectiles ? They can be turned and grooved, 
though it is more expensive to do so than with ordinary cast-iron. 
It would be better, however, to cast the shot in a cylinder of cast or 
wrought-iron, and groove the outer casing thus formed. A wrought- 
iron casing would be a very great advantage; because on striking an 
iron plate the tendency of the body of the shot is to split in two and 
fly forward like lead-coating, while the head jams in between the two 
pieces, but a wrought-iron casing would prevent this.* 
Another great advantage is that it could be used with breech-loading 
as well as with muzzle-loading guns. It is by no means an easy problem 
to solve how we are to secure that the projectile shall occupy its proper 
seat if we do away with lead-coating; because any arrangements made 
when the gun was new might fail if the bore was worn out by scoring’. 
It would be very easy to stop the scoring on this plan by a wad; for 
the sharp edges of the ribs would readily cut int6 the wad and preserve 
the bore, or at all events the ribs themselves, from being eaten away. 
All that would have to be done would therefore be to insert small zinc 
studs in a few of the grooves, and allow the projectile to go up until 
these studs come to where the ribs terminate beyond the powder- 
chamber. These zinc studs would probably afterwards aid the centring. 
The bore would thus not only not be weakened, as in nearly every other 
system, by narrow deep grooves cut in the most vital part of the gun, 
but would not wear out by scoring; and if combined with the gun 
brought forward by the writer in this Institution nearly four years ago,f 
the endurance of our heaviest guns would probably be extended to 
* Captain C. Orde Browne, late R.A., and Captain Instructor Royal Laboratory, in “ Proceedings} 
Royal Artillery Institution,” Vol. VII. page 25, says:—“ The projectiles cast with sand bodies are 
superior in penetration to those entirely chilled; because, as may be seen, while the pressure round 
the head towards a centre does not test its tenacity, the base is in a very different condition. The 
metal then having lent its force to some extent to the head, shivers away to the front, generally 
indenting the plate round the hole made by the head. Any increase of tenacity in the material at 
the base is therefore clearly an advantage.” 
f See “ Proceedings, Royal Artillery Institution,” Vol. VII. pp. 145 and 436. 
