CAPILLARY RIPPLES. 593) 
error of tone, either sharp or flat, would at once send these rings one 
way or the other; if they went out he would be sharp; if they went 
in they would be flat ; and, therefore, there is no occasion for judgment. 
This is more precise than any judgment. 
And now, in conclusion, I have only to say that I have been working 
under considerable difficulties to-day, and I hope that the somewhat 
lame way in which only I have been able to succeed has not been such 
as to prevent your having been interested in the matter that I have put 
before you (loud applause). 
DISCUSSION. 
Masor P. A. MacManon, R.A., F.R.S.—Notwithstanding what was said 
by Colonel Lockhart in introducing the lecturer to us I think that considerable 
difference of opinion existed before the lecture as to the exact nature of the 
matter that was to be brought before us, but I think now that the lecture is con- 
cluded we find ourselves in perfect agreement in regard to the charm of that to 
which we have listened and to the great experimental ability that has been 
exhibited before us. I believe that the experiments have been completely success- 
ful and this in spite of the difficulties, in no way due to the lecturer, that suddenly 
presented themselves this afternoon; difficulties that must have proved insur- 
mountable to one less expert and resourceful than Professor Boys. 
He has brought before us wave motion, a subject most interesting to us in our 
profession. Wave motion is the common ground of the physical sciences— 
chemistry, heat, light and electricity and enters notably into the physics of the 
science of artillery. He is happily no stranger in the theatre of this Institution 
and many of us present here this evening must remember his photographs of 
flying bullets that enabled us to follow the projectile in its flight and to observe 
the attendant trains of waves with a clearness of vision that had not previously 
beeu possible. This, in my view, was great work in gunnery. It is again an 
auspicious circumstance that Professor Boys has recently become interested in the 
mode of action of various explosive substances. In the powder chambers of guns 
we frequently find abnormal pressures arising from wave action in the gases pro- 
duced by the combustion of the explosive. These pressures constitute one great 
difficulty in our subject. Very little is known about them. The associated 
experimental work is of the most refined and delicate character. If those who 
have the power will keep the attention of Professor Boys riveted upon this matter 
and take action such as will stimulate his interest and curiosity I feel certain that 
advantages will accrue to our science that, probably, we could obtain in no other 
way. He may soon render us further signal service in this direction. Certainly 
we may assure him that we are hopeful and expectant. 
No one could have listened to the lecture without realising the extraordinarily 
minute character of the materials dealt with and of the phenomena exhibited. 
We may be sure that the necessary experimental skills varies according to a high 
negative power of the size of the subject matter. It is most gratifying to know 
that the lecturer is fully equal to the demands and in the respects mentioned is 
notoriously unapproachable in this country. Before sitting down I would say 
that I think we may heartily congratulate ourselves that various artillery problems 
are gradually coming under the strong hand of Professor Boys. 
Prorgssor GREENHILL, F'.R.S.—-I am pleased to have the opportunity, Sir, 
of expressing the very great pleasure that I have felt in listening to Mr. Boys’ 
lecture. 
8 
