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Proceedings of the Royal Society 
higher vantage ground opened to the mathematician by means of 
Peaucellier’s discovery. The extent of our own obligation to him 
is great. 
Not less are we indebted to Professor Kelland, whom we have 
known both as a teacher and a friend. The valuable hints and 
suggestions he has given us on this subject we are glad to take 
this opportunity of acknowledging. 
3. Laboratory Notes. Ity Professor Tait. 
(«.) On the Passage of the Electric Current from Amalgamated 
Zinc to Zinc Sulphate Solution. By J. G-. MacGregor, 
M.A. 
(5.) On the Thermo-Electric Properties of Cobalt, &c. By Messrs 
Knott, MacGregor, and C. M. Smith. 
(c.) Measurements of the Potentials required for Long Sparks of a 
Holtz Machine. By Messrs Macfarlane and Paton. 
4. Note on Orthogonal Isothermal Surfaces. By 
Professor Tait. 
5. Notice of some recent Atmospheric Phenomena. 
By Professor Tait. 
6. Keport by the Society’s Boulder Committee. (Plates 
II. and III.) 
Mr David Milne Home gave in the Third Report of the Society’s 
Boulder Committee, from which the following are extracts : — In 
November 1875, on the invitation of Sir John Douglas of Glen- 
finnart, the Convener went to visit him at that place, to have an 
opportunity of examining several remarkable boulders reported to 
the Committee as situated in that part of Argyllshire. 
1. On the east side of Lochlong, opposite to Ardentinny, there 
is the farm of Peaton. On this farm, a burn descends from a 
steepish hill which faces the north. A gneiss boulder lies in a 
gorge cut by the burn through rocks of clay slate. The boulder 
