460 
MINUTES OF PROCEEDINGS OF 
In theory it is | for spheres, 1 for a disc, and § for a cylinder (moving 
sideways). In practice it is perhaps for spheres. 
On this supposition of incremental velocities it is easy to obtain the 
equations to the trajectory considering the wind. It would be necessary to 
use these equations to calculate on this hypothesis, the effect of wind on the 
shot, when it strikes it in a direction not perpendicular to the trajectory, 
which will in any case however be a curve of double curvature. 
This will finish the first section of this paper. The second section I shall 
briefly dispose of. It is entitled Defects of Construction, and comprises :— 
(y) Defects of construction proper; 
( S) Defects of system. 
Defects of construction proper are the following :—■ 
Eccentricity of the shot arising from want of homogeneity, 
Faulty position of the line of sight, otherwise bad sighting, 
Irregularity of calibre, 
Flexure of axis, from accident, or in manufacture. 
r guns, 
Defects consequent on bad materials < projectiles, 
(.explosive materiel. 
I have left out of consideration the first of these causes of deviation, as it 
may be considered as a mere species of accidental rifling; for from the greater 
surface exposed to the action of the powder while in the bore, the shot will 
always have a fixed rotation round the front, from the side opposite to that 
on which the centre of gravity was situated in the bore at loading. 
Bad Sighting . 
There is a curious defect however in sighting, manifest in some six- 
barrel revolvers, and also in some double-barrelled guns and rifles, owing 
to the sights being placed between the barrels, and the axes of the latter not 
being parallel. For, as the breech is generally thicker than the chase, the 
barrels will not fit together at the same time that their axes remain parallel, 
unless either the breeches be filed (a very objectionable practice), or some 
hard substance be interposed between the barrels. An error in this way 
will sometimes produce six inches in 40 yards, whereas the real error ought 
not to be more than the radius of the bore. This circumstance has been 
very much attended to of late years, especially by the best makers. 
Irregularity of Calibre. 
Mr Whitworth, in the experiments conducted in his own ground at Man¬ 
chester, and by the use of his difference gauges, which will measure sizes 
mechanically up to the millionth part of an inch, has proved that no reliance 
may be placed on the most carefully finished barrels. He found that even 
the best specimens had bores entirely devoid of all truthfulness, and com¬ 
posed of inequalities, which must have greatly detracted from the accuracy of 
fire. Thus the barrels were conical in one direction in one part, and the 
