of Edinburgh, Session 1877-78. 
581 
of Sir William Thomson’s recorder. This siphon deposited the 
trace of the curves on a paper strip rolled on the periphery of the 
large disc used by us for the experiments on friction published in 
the “Transactions of the Royal Society of London” for 1877. 
The authors had not yet had time to analyse these curves and 
compare them with Helmholtz’s theory of vowel sounds. 
The advantage of recording the curves corresponding to the 
several sounds indirectly by means of the tinfoil, instead of directly, 
as in the case of the phonautograph, consists in the fact that with 
this arrangement the amplitude of the oscillations may he greatly 
magnified without introducing any sensible error due to the inertia 
of the moving parts. The paper band and tinfoil record were 
moved at a very slow speed, and their relative advance was 
rendered quite definite by a mechanical connection between the two 
barrels on which they were wound. 
The following Gentlemen were duly elected Fellows of the 
Society : — 
Charles Davidson Bell, Retired Surveyor-General, Cape of Good Hope, 
19 Dean Terrace. 
James Blyth, M.A., 8 Middleby Street. 
R. K. Galloway, M.A., Jesus’ College, Cambridge, 10 West Claremont 
Street. 
Monday, 18 th March 1878. 
Sir WILLIAM THOMSON, President, in the Chair. 
The following communications were read : — 
1. On Thermal Conductivity. By Professor Tait. 
(Abstract.) 
This paper contains the results of a laborious series of experi- 
ments and calculations carried out during the last ten years, the 
object being the repetition and extension to other metals than iron 
of Forbes’ experiments, described to the Society in 1862 and 1865. 
As a check upon his work, the author first experimented upon the 
VOL. ix. 4 H 
