156 Proceedings of the Royal Society, 1863-64. 
assumption, as if it were an axiom, of the proposition “ That the 
angles of a triangle are together less than two right angles.” The 
results as regards the theory of parallels are such as to imply that 
such lines would have most of the properties of equal circles ex- 
terior to one another. 
Professor Tait reminded the Society that, at the close of last 
session, he and Balfour Stewart, P.E.S., of the Kew Observatory, had 
deposited with the Secretary a sealed packet containing the coin- 
cident results of certain investigations which they had separately 
carried on from totally distinct points of view, and which appeared 
to lead to a new principle in Natural Philosophy. 
Experimental attempts at verifications of this principle have 
since been made by them in various ways, and others are in pro- 
gress. Meanwhile, the authors desire to put on record that it 
appears probable, from their experiments, that the viscosity, &c., of 
air are not the only causes of the increased radiation from a moving 
body. (Compare Joule and Thomson, Phil. Trans. 1860.) A 
vacuum apparatus now in course of construction, will, it is hoped, 
lead to decisive results. 
The following Gentlemen were elected Fellows of the 
Society : — 
Andeew Wood, M.D., F.R.C.S.E. 
Eobert William Thomson, Esq., C.E. 
The following Donations to the Library were announced » 
Monthly Keturn of the Births, Deaths, and Marriages Eegistered 
in the Four Principal Counties of Scotland. October 1863. 
8 VO. — From the Registrar -General. 
Journal of the Eoyal Geographical Society. No. 32. 8vo. — From 
the Society. 
Transactions of the Linnean Society. Vol. XXII., Part II. 4to. — 
From the same. 
Journal of the Chemical Society. No. 12. 8vo. — From the same. 
Transactions of the Eoyal Society of Literature. Yol. VII., Part 
III. 8 VO. — From the same. 
American Journal of Science and Arts. No. 108. 8vo. — From 
the Editors. 
