of Edinburgh, Session 1881-82. 743 
The President announced that the Council had awarded the 
Keith Prize, for the Biennial Period 1879-81, to Professor Chrystal, 
for his paper “ On the Differential Telephone,” published in the 
Society’s Transactions for the Session 1879-80; and the Keill 
Prize, for the Triennial Period 1877-80, to Mr. John Murray, for 
his paper “ On the Structure and Origin of Coral Eeefs and 
Islands,” communicated to the Society on 5th April 1880, and 
printed (in Abstract) in the Proceedings for that date. 
The President read a letter from M. Dumas, perpetual Secretary of 
the Academy of Sciences, Paris, inviting the Bellows of the Society 
to subscribe to a Fund to be formed, in order to present to 
M. Pasteur a Medal, commemorative of his work and services. 
Professor Tait announced that the Council had replied to M. Dumas’ 
letter, informing him that the Society has no funds which can be 
devoted to such a purpose, but that an opportunity would be given 
to individual Fellows of subscribing to the Medal to be offered to 
M. Pasteur. 
The following Communications were read : — 
1. On Mirage. Part II. By Professor Tait. 
2. Beport of the Boulder Committee, with Bemarks by the 
Convener, Mr. Milne Home. (Plate V.) 
The Convener being now no longer able to climb hills, or walk 
to any considerable distance, his own contribution of information 
to the Committee is, this year, exceedingly small. 
I. Cantire. — Loch Tarbert. 
The only place visited by him during last autumn was East Loch 
Tarbert, Loch Fyne, at the suggestion of Mr. Alexander of Loch- 
gilphead, whose services to the Convener during the two previous 
years were peculiarly valuable. 
Having procured a horse, the Convener, under Mr. Alexander’s 
guidance, rode up two-thirds of a hill, about two miles to the 
K.W. of East Loch Tarbert, on the property of Mr. Campbell of 
