of Edinburgh, Session 1874-75. 491 
two very light closed cylinders which fit very closely (but without 
touching) into two fixed cylinders open at the top. Applied to a 
long and massive beam with considerable loads in the scale-pans, 
and which vibrated for some minutes when disturbed, this trial 
apparatus brought it to rest after, at most, three half vibrations. It 
is now evident that with a properly-constructed damper on this 
plan, there is practically no limit (so far as rapidity of weighing 
alone is concerned) to the length which may be given to a balance- 
beam ; and, of course, no limit to the consequent sensibility of the 
instrument. 
A very instructive hydrodynamical result was observed with this 
arrangement. The closed cylinder, exactly balanced inside the 
cylinder open at the top, is made to ascend briskly by a current 
of air blown even vertically downwards on the centre of its upper 
end. 
b. Photographs of Electric Sparks taken in Cold and in Heated 
Air. 
( Ordered by the Council to be 'printed in the Transactions . ) 
c. On the Electric Resistance of Iron at High Temperatures. 
This note details various experiments made for me by Messrs 
C. M. Smith and A. Macfarlane in the Physical Laboratory of the 
University, and has been drawn up by these gentlemen. The only 
part I have taken in the work has been the suggestion of the line 
of investigation and the forms of apparatus employed. I mention 
this not alone injustice to them; but also as giving independent 
corroboration of results formerly arrived at by myself. [ This paper 
will be inserted later , when the necessary diagram is ready.] 
Monday , 1st March 1875. 
Sir WILLIAM THOMSON, President, in the Chair. 
The following Communications were read : — 
1. Biographical Notice of William Euing, Esq., F.R.S.E. 
By Professor William P. Dickson. 
William Euing was born on 20th May 1788, at Partick, where 
