THE ROYAL ARTILLERY INSTITUTION. 
239 
under these circumstances subject in respect to its rotation and deflection 
to the same laws and influences, and to no others. Now, the Diaphragm 
shell is from its construction, and from the fact of its having a wood bottom 
attached, a projectile of this nature,—that is to say, although eccentric, it is 
always necessarily placed in the bore with the line joining its centre of gravity 
and figure parallel to the axis of the piece and thus no rotation is generated 
in it which would not be generated in a concentric projectile, 4 and therefore 
no deflection or inaccuracy of flight, results from its eccentricity. 
But more than this, it may be shown, as already stated, that “ these shells 
should, theoretically, be even more regular in their flight than an ordinary 
shot of the same weight.” 5 This is not difficult to prove; for, it will be 
apparent to any one who has followed the above remarks carefully, that " if 
eccentric projectiles be always placed in the gun in similar positions as 
regards the lines joining their centres of gravity and figure, whatever that 
position may he, their path will be more regular than that of ordinary round 
shot placed accidentally in the bore,” 6 because in the one case the direction 
of rotation is known and determined, in the other,—the case of ordinary round 
shot,—it is uncertain and variable, owing to the fact of nearly all ordinary round 
shot being more or less eccentric, 7 and the position of their centres of gravity 
and figure undetermined; it follows, therefore, that the practice with ordinary 
round shot will be less accurate than the practice with Diaphragm shell, the 
line joining the centres of gravity and figure of which always occupies, as has 
been explained, a known and uniform position in the bore. And how 
much more must the advantage incline to the side of that projectile of 
which the eccentricity is, so to speak, neutralized, by its always occupying a 
position in the bore which prevents any deflection due to eccentricity being 
produced. In other words, the comparison lies between projectiles more or 
less eccentric, and which occupy accidental positions in the bore, on the one 
hand,—and projectiles which are virtually concentric, on the other; there 
can hardly be much difficulty in determining which of the two should 
theoretically be most accurate in flight. 
2. The second objection which has been urged against the Diaphragm 
shell is, That the bullets are acted upon by the bursting charge, in a way, 
and to an extent highly injurious to the efficiency of the shell? 
4 “ Although the Diaphragm Shrapnel shell, when prepared for service, is from the relative 
positions of the bullets and powder, what is termed eccentric, still no rotation will be generated in 
the bore from this arrangement, as the wood bottom which is firmly riveted to the shell, always 
ensures the straight line which joins its centre of gravity and centre of figure, being in a position 
parallel, or very nearly to that of the axis of the bore, or the line representing the direction of the 
propelling force.”— Remarks on Diaphragm Shrapnel Shells,])]). 22, 23. 
5 Col. Boxer’s Remarks on Committee’s Memo, on Diaphragm Shrapnel Shell, p. 4. 
6 Remarks on Diaphragm Shrapnel Shells, p. 22, Col. Boxer adds: “The results of the experi¬ 
ments which were made in 1850 and in 1851, at Shoeburyness, notwithstanding the imperfect mode 
adopted to secure the proper position of the eccentric shot, confirms this view.”— Ibid, p. 22. 
- ^ From the difficulty, almost amounting to an impossibility, of casting a perfectly concentric 
sphere of iron, or any other metal. 
a See Ordnance Select Committee Report on Shrapnel Shell, p. 192—297. 
