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Proceedings of the Royal Society 
impossibility, that there could have been glaciers in these two glens 
at the time that there were lakes in Glen Roy and G-len Spean. 
Even if there had been glaciers in these glens, these glaciers, 
to reach the position of the G-len Roy barriers, would, after emerging 
from their parent glens, have had to travel seven or eight miles 
across uneven ground, push themselves round the corners of several 
hills, and rise up to a level several hundred feet above these glens. 
If it was possible to suppose that the tongues of these glaciers could 
reach the required spots, the notion of their forming solid and 
permanent barriers at these spots seems quite untenable. 
Monday , 5th February 1877. 
Sir WILLIAM THOMSON, President, in the Chair. 
The following Communications were read : — 
1. On some Effects of Heat on Electrostatic Attraction. 
By Professor Tait. 
2. On the Curves produced by Reflection from a Polished 
Revolving Wire. By Edward Sang, Esq. 
When a polished thin straight wire turns on a fixed point in 
space, the point at which light coming from a fixed source is re- 
flected, moves in a curved surface. In this paper the motion of 
the wire was supposed to be restricted to the plane passing through 
the eye and the source of light. The curve was shown to be of the 
third order, having a straight line as a symptote both ways, and to 
depend for its form upon a characterising angle. The interest of 
the subject lay chiefly in the remarkable transformations of the 
curve. 
3. On an Ammonia-Cupric Zinc Chloride. By 
E. W. Prevost, Ph.D. 
The following is but a short and incomplete account of a com- 
pound formed on the carbon and binding screws of a makeshift 
Leclanehe battery. The cells employed were ordinary Bunsen ele- 
ments, of which the carbon was embedded in manganese dioxide ; 
