THE ROYAL ARTILLERY INSTITUTION. 
473 
either cast or planed to fit the bore, leaving a small windage. The 
body of the shot is therefore in immediate contact with the bore of the 
gun_, both while loading and firing. 
In the service or “ Woolwich'' rifling, helical grooves are cut in the 
cylindrical surface of the bore, and the projectile is armed with studs 
or buttons of soft metal, which fit the grooves and project to such a 
distance from the body of the shot as to prevent its surface from coming 
in contact with that of the bore. 
The principle involved is therefore generally described as that of 
cc soft-metal bearings.” This principle is common to many other systems 
of rifling—as, for example. Sir W. Armstrong's shunt, the French, 
Captain Scott's, &c. In such methods, the whole work, both of guiding 
and spinning the shot, is thrown upon the projections on the shot and 
the grooves of the gun, the bore proper serving only to confine the 
elastic gas produced by the gunpowder. 
The principal advantage claimed for the Whitworth system, is the 
simplicity and cheapness of the projectile. Special virtues have also 
been attributed to it, though perhaps not by Sir J. Whitworth himself;* 
1st, as producing great range and accuracy, and 2nd, penetrative effect 
at long ranges. These are, however, due to smallness of bore, and are 
not at all peculiar to polygonal rifling. As regards the first, it will be 
useful to notice what has happened in the case of small-arms. 
It is notorious that to Sir J. Whitworth is due the determination of 
the proper calibre and degree of rifle-twist for a bullet of 530 grains. 
His calibre and twist have been substantially adopted by all good gum 
makers and rifle-shots in this country, but the polygonal rifling has 
been abandoned. In the last International Competition at Wimbledon 
for the Elcho Challenge Shield, in which twenty-four competitors were 
engaged, not a single Whitworth rifle was used; and in the same com¬ 
petition of the preceding year, only one was used, the score made with 
which was the worst of the whole twenty-four. 
But the objections to polygonal rifling for guns are far more decided 
than for small-arms, where a soft lead bullet is used. 
In the case of guns, the projectile has been found liable to jam in the 
bore while loading, as instanced in the trial of the 7-inch 7-ton gun at 
Portsmouth, already referred to; and it is known, from confidential 
official reports to the Foreign Office, that the same defect was observed 
by the Brazilians, Who used several Whitworth guns during their recent 
War with Paraguay. 
This jamming also occurred in the case of two 80-pr. Whitworth 
guns used during the American war, in the attack on Charleston, 
August, 1863. (See Appendix IY. to “ Correspondence, &c.'' 1867.) 
Such a defect is of itself sufficiently serious to condemn the system, 
whatever may be the advantages claimed as regards simplicity and 
cheapness of projectile. 
* Before the Ordnance Committee of 1863, Sir J. Whitworth stated :—“ There are many forms 
of rifling, which, if the gun is kept clean, will shoot well if it be accurately made; and those who have 
a knowledge of accuracy of measurement and of true surface may make rifle guns shoot well with 
various forms of rifling.”—See “ Blue-Book,” p. 106, question 2454. 
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