526 The British Association . [October, 
to the diameter of rings, and also the angles between the 
optic axes. 
A telegram and letter from Prof. W. C. Ayrton, of Japan, 
to Sir Wm. Thomson, “ On a New Determination of the 
Number of EleCtro-static Units in the EleCtro-magnetic 
Unit,” were read. The letter gave an account of very inte- 
resting and delicate experiments, which resulted in an answer 
of 298,000,000 metres per second, corresponding with the 
velocity of light as given by Foucault. 
Mr. R. J. Moss gave a description of an instrument of 
research for the investigation of Crookes’s stress and experi- 
ments on spheroidal drops. 
Prof. Barrett described a new form of trap-door electro- 
meter. 
Mr. J. E. Gordon described some experiments on specific 
inductive capacity. His observations were illustrated by 
formulae and coloured diagrams, without which they cannot 
be well understood. 
At the request of the Chairman, Prof. W. E. Ayrton, who 
had just arrived from Japan, said — The value of Mr. Gordon’s 
experiments arises from his belief that the specific inductive 
capacity of a dialectric rapidly increases with time. As 
Mr. Gordon has remarked, Prof. Perry and myself were 
theoretically led to this idea several years ago, as we described 
in our paper on the “ Viscosity of Dielectrics” some time 
back, and which appears in a recent number of the “ Pro- 
ceedings of the Royal Society of London.” The idea that 
all dialectrics behave more or less like strained viscous sub- 
stances has been the leading principle that has guided 
Prof. Perry and myself in our electrical observations — an 
idea to which our attention has been especially directed in 
the following way : — When Mr. Perry was examining certain 
curves obtained for the time increase of strain in a substance 
subjected to a constant stress simultaneously with some that 
we had obtained for the soaking out of the charge in an 
excellently well-insulated Leyden jar, the coatings of which 
had been maintained for days at a constant difference of 
potentials, then suddenly discharged, and finally insulated 
the one from the other, he observed a remarkable analogy 
between the two classes of curves, and careful examination of 
all our results up to the present time bears so close an analogy 
with the stress and strain phenomena in various substances, 
that we feel that this analogy means a physical connection. 
Reasoning by analogy, we may conclude that as the rate of 
production of eleCtric strain grows less and less as the in- 
