466 
THE DRIFT OF SERVICE PROJECTILES. 
DISCUSSION. 
The Chairman —This time last year General Owen gave us a lecture on this 
subject and he implied that we had made no progress in it since his time, which 
was some 20 years ago or more. All I want to know is what is the cause of this, 
if it be so. Is it because we accept the theories of the text-book that we have 
got and are quite content, or is it from want of energy ? I cannot think that it 
is from want of energy. Am I to think then that we are content with the theories 
that we have got ? Captain Shortt to-night, by different methods, seems to have 
arrived at very nearly the same conclusion as Professor Bashforth (, see para. 143 of 
Bashforth’s Chronograph, edition, ] 890). In all the four quadrants of motion of 
the projectile round the trajectory, as to the point and the position of the axis, 
Captain Shortt entirely agrees with what Professor Bashforth says; and the 
reason for drift, too, as given by him, is also very much the same, as Bashforth 
concludes the paragraph with the- following remarks : “ Hence we may conclude 
that the drift will be in operation for a much longer time to the right than to the 
left.” Therefore, the agreement of Captain Shortt with Professor Bashforth would 
lead me to hope that this theory or something like it may be the accepted one. 
But, at any rate, Captain Shortt’s opening of this discussion will, 1 hope, bring 
us to some definite conclusion to-night so that we may not be told that we have 
made no progress in the last 20 years (applause). 
Major A. J. Abdy (Secretary)— I have here, sir, two letters, one from 
Professor Boys, who writes as follows 
“ 27, The Grove, 
“ Boltons, S.W., 
<£ Dear Abdy— <£ 15th January , 1897. 
“ Most unfortunately I am lecturing at the London Institution on 
Monday afternoon, the 25th, which completely destroys all chance of 
coming to Woolwich, which I should like to have done. 
“I was fortunate to have called on Professor Perry when Captain Shortt 
was explaining his views upon the precession and drift of shot. Wliile 
I felt that the reasoning was just and accurate, my quantitative sense 
was not satisfied. Though, no doubt, mathematical analysis is not com¬ 
petent to give a complete and exact solution, I cannot help thinking 
that some very remarkable approximations to the truth could be obtained 
by dividing the path into a number of small stages in each of which the 
actions should be supposed uniform, from the known resistance on the 
head of the shot to make a reasonable guess at the amount of pressure 
and the position of the centre of pressure for any given small inclination 
and so laboriously, step by step, to find a polygonal approximation to the 
true curves. Even if such an approximation were very rough, it would, 
at any rate, afford some evidence as to the proper time of the beating of 
the shot, which Captain Shortt has observed. 
“I feel that some quantitative estimations, however rough, would 
enormously add to the value of the paper, but perhaps Captain Shortt 
has figures to adduce which he has not printed in his abstract. 
ft Yours truly, 
“C. V. Boys.” 
And I have also a letter from Major-General C, H. Owen which he asked me to 
