592 Proceedings of the Boyal Society 
La Kepubblica di Venezia e la Persia, per G-uelielmo Bercbet. 
Torino, 1865. 8vo . — From the Italian Government. 
Relazione della direzione tecnica alia direzione generale delle 
strade ferrate dello state. Torino, 1863. 4to . — From the 
Italian Government, 
Monday, 6th March 1866. 
In the absence, from illness, of Sir David Brewster, the chair 
was taken, ^ro tern., by Professor Tait, on the motion of 
Professor Balfour. 
In delivering the Keith Medal to Principal Forbes, Professor 
Tait said — “ The suddenness of this summons, and my consequent 
total want of preparation, may well excuse me if I fall short of what 
is due to the Society or to Principal Forbes on this occasion. 
Nothing, however, could be more agreeable to myself than to per- 
form such a duty to him who was my earliest instructor in the 
science I now profess. Principal Forbes has already obtained this 
prize, and has, during a long and active career of investigation, 
over and over again merited it. As one of his unrew'arded works 
which may be taken as a type of their value, I may merely men- 
tion his Theory of Grlacier motion, which, in spite of ignorant and 
invidious criticism, still remains the true statement of the observed 
phenomena — all it pretended to be. 
“ Happily, with reference to the paper which has won the honour 
I have to confer, I am provided with the opinion of perhaps the 
greatest living authority on the subject of Heat, Professor W. 
Thomson of Glasgow. As one of your secretaries, I had obtained 
it from him, with the view of its being incorporated in the address 
which ill health has prevented our President fro^m delivering on 
the present occasion. The reading of this is all that is necessary 
to prove to you how justly the medal has been merited. 
Principal Forbes’ experimental investigation of the thermal 
conductivity of iron has enlarged our knowledge of the properties of 
matter with information, which is not only of extreme interest and 
