THE EXHIBITION OF 1862. 
165 
thus produced passes into an annular space formed within the revolving 
cover, which rests on the upper surface of the fuze composition ; and from 
this annular space it is directed outwards through an opening, so as to 
impinge on and to ignite the fuze composition at any required part of the 
circle. The fuze thus ignited burns in both directions, but only takes effect 
at one extremity, where it communicates with a small magazine of powder in 
the centre. The fuze is surrounded by a scale-paper, graduated to accord 
with the elevation of the gun, so that when the range of a distant object is 
found by trial, it is only necessary to turn the igniting aperture of the cover 
to the point on the fuze scale corresponding with the degrees and minutes of 
elevation on the tangent scale. 
The concussion fuze (fig. 4 ) is on nearly the same principle. A striker with 
a point presented upwards is secured in a tube by a wire fastening, which is 
broken on the firing of the gun ; the striker being thus liberated, recedes 
through a small space, and rests at the bottom of the tube ; but, as soon as 
the shell meets with any check in its motion, the striker runs forward and 
pierces the detonator in front ; by which means the bursting charge is 
ignited. 
Tlie Whitworth gun may be either a breech-loader or a 
muzzle-loader, — that is to say, some are made to load at the 
breech ; but their construction is such, that if anything in the 
breech-loading apparatus should go wrong-, the gun is not dis- 
abled, as with the Armstrong, but can be loaded at the muzzle. 
The form of the bore can perhaps best be understood by 
examining the shot of which drawings are given (figs. 5 and 6), 
and imagining the bore which will fit them. It is in fact in 
section a hexagon with the angles rounded off. If we imagine 
this section to move along the bore with a rotation which would 
make one complete turn while moving along a length of twenty 
diameters (which is the pitch given in the Illustrated Catalogue 
of the Exhibition, from which the drawings are taken, for all 
calibres), it gives the bore. Mr. Whitworth constructs all his 
guns of homogeneous iron, the smaller calibres being simply 
bored out of a solid bar, and the larger ones strengthened by 
wrought-iron hoops forced on by hydraulic pressure. To secure 
ease in loading, without windage (except to a very small ex- 
tent), those portions of the sides and angles of the hexagon of 
the bore on which the shot bears while being rammed down 
from the muzzle, are eased off slightly. The shot bearing close 
on the other portions when being driven out by the powder, 
prevents nearly all waste by windage. The ordinary shot, which 
is cast, is put into a lathe to be faced to fit the bore, though, on 
occasion, it may be finished in casting-. Mr. Whitworth has 
found that, by diminishing off the tail of the projectile, as shown, 
a greatly increased range is obtained. The shot with which the 
extraordinary penetrations, lately reported in the newspapers, 
was obtained against iron plates, is of the form shown in fig. 6, 
