THE ROYAL ARTILLERY INSTITUTION. 
237 
quite possible that the Accuracy of Fire at some particular practice may be 
very inferior, while the Accuracy of Flight is all that can be desired; for 
Accuracy of Flight being, as has just been pointed out, only one of the 
elements of Accuracy of Fire, the failure may arise from any other of those 
elements which I have enumerated. 
In this way much confusion and difference of opinion may exist as to 
the proper application of the term “ accurate” and “ inaccurate” to any 
particular practice with this class of shells; while even with the best inten¬ 
tions, and the clearest and most correct views upon the subject, the 
distinction is not an easy one to make practically with shells which generally 
burst, it must be remembered, before they graze. 
The proper way to determine the Accuracy of Flight of Diaphragm shells 
is to fire a number of them blind ; but neither of the two officers from whose 
reports I have quoted, make any mention of having done this. 6 
I observe, also, on examining the Practice Reports upon which the 
second of the two unfavourable reports is based, and other Practice 
Reports given in the Committeds Memo, on Diaphragm Shrapnel Shells, p. 9 
to 58, that where the shells failed to burst, the accuracy of flight seems to 
h#ve been very good; generally the shells which so failed went through the 
target, in the majority of the other cases they were “in the line,"” and when 
not in the line the deflection right or left is generally inconsiderable. I think 
this is very strong proof that inaccuracy of Flight and inaccuracy of Fire were 
not always carefully distinguished from one another, and that the former 
term was often misapplied. 
I may now pass on to the Theory of the question, and prove that even if 
the testimony to inaccuracy of flight been universal, and the fact been placed 
beyond all possibility of doubt, the defect could not properly be assigned to 
the cause from which the officers who reported upon the subject believed it to 
proceed,—prove, in short, that any observable inaccuracy of flight on the part 
of these projectiles could not be in any way connected with their eccentricity. 
In the case of all spherical projectiles fired from smooth-bored guns there 
is a certain rotation generated in the bore,—arising, when the projectile is 
concentric, principally from the windage ; 7 and where the projectile is eccen¬ 
tric, and the line joining the centres of gravity and figure is not in, or parallel 
to, the axis of the bore, from the powder acting upon a larger surface on one 
side of the centre of gravity than on the other, and so producing a rotation 
about the centre of gravity. 8 Now the direction of the rotation wdiich arises 
6 It is worthy of observation that there is no reoord of any such experiments having been made; 
and this may fairly be accepted as a sort of negative proof that those who practised and 
experimented with the shells were generally well satisfied with regard to their Accuracy of Flight; 
otherwise it is reasonable to suppose, that so grave a defect would have been tested by an experi¬ 
ment specially calculated to expose it. 
7 “There is a considerable degree of friction between the bore and the projectile.where there 
is windage, the direction of the force being opposite to that of the gunpowder, and upon the surface 
of the ball. It will therefore tend to give rotation to the shot .”—Treatise on Artillery , Section 1, 
Part I. p. 158. 
“ Friction.is the only immediate cause of deflection in a projectile whose centres of figure 
and gravity are coincident.”— Ibid, p. 166. 
8 Motion of'projectiles, p. 125, par. 19. 
“Suppose the ball to be perfectly round, but its centre of gravity not to coincide with the centre 
