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THE DRIFT OF SERVICE PROJECTILES. 
were as follows :—Range, about 2000 yards; time of flight, something over 60 
seconds; and the drift was about 1300 feet to the left, suddenly and quite 
unexpectedly. We were firing, I think, with over 67° of elevation, and, on 
slightly increasing the elevation to get the range, suddenly we found the shot 
going 100 yards or so to the left of the splinter-proof, in which were several 
officers and men. In the shell there was 32 lbs of high explosive, which, on 
bursting, made a crater in shingle of 50 cubic yards in extent, so that it was 
rather an important matter. 
Captain J. W. Ormiston —I should like to know whether in the howitzer 
practices that have been referred to by Colonel Rainsford-Hannay and Captain 
Osborn they were speaking of groups of shots or of isolated shots that fell to 
the left ? 
Captain Osborn —x\ number of shots; they are down in the Ordnance 
Committee’s report. 
Captain Cooper and Professor Greeniiill showed some experiments with 
the ( jyrostat , etc . 
REPLY. 
Captain Shortt — Professor Bashforth gives his reason for drift, that 
“ because the first motion is to the right and afterwards because the point is 
more to the right than to the left, the drift is to the right.” I agree with the 
last reason, but I have never seen any explanation why it is so before, and that 
is what I have tried to supply to-day. As General Owen says, in the second 
quarter, although the point is coming in yet, it is still on the right and the air 
must be still acting on the left side. That I agree with, of course. He says 
also that it cannot complete one or more revolutions, that, of course, I differ 
with and I have shown why; and I think I am borne out by practical results. 
I think that the noise one hears in flights cannot be due to anything else but 
that; I never heard any other theory of it. 
As regards the position of the centre of gravity, of course if the centie of 
gravity wer6 right forward or right back, it would make an enormous difference, 
as Major MacMahon says. For that reason I limited my lecture to service shot. 
If you put the centre of gravity right forward as it is in a rocket then the 
projectile will keep point forward almost without rotation at all; but I was 
limiting myself to the position of the centre of gravity more or less in the middle. 
The only thing I took my stand on was that the air would drive the point away 
from the trajectory, and for that the resultant, if you call it so, of the direction of 
the resistance of the air must act in front of the centre of gravity. 
I see, of course, the force of Major MacMahon’s argument about symmetry; 
that certainly did not occur to me, but as the resistance decreases without 
reference to any particular position of the point, I don’t see how it can give the 
point a bias in any particular direction. It does not affect my argument about 
the point in a curved trajectory being more to the right, I think. 
As regards there being less drift in a high velocity gun, there is also, I think, 
in a high velocity gun less drift, compared with the time of flight, than in a 
howitzer. I think I am right in saying that in a howitzer for every second there 
is considerably more drift than in a high velocity gun. 
As to a billiard ball’s drift, I do not know, I must say. I had not heard of 
the theory, and I know nothing about it. That a golf ball drifts only with 
low velocity, 1 have seen, and the same with a tennis ball. I may say that I 
entirely agree with Captain Maunsell in what he said at the last lecture about the 
