592 
Proceedings of the Royal Society 
Jc being the dynamical value of the real specific heat ; U, tlie 
potential energy of the elasticity of the body at constant tempera- 
ture; and X (r), a function of the absolute temperature, which is 
null or inappreciable in a substance capable, at that temperature, 
of approximating indefinitely to the perfectly gaseous state, and is 
included in the formula, in order to provide for the possibility, 
suggested by Clausius, that there may be substances which have 
not that property at all temperatures]. 
6. On the Rotation of a Rigid Body round a Fixed Point. 
Part II. By Professor Tait. 
The following Gentlemen were elected Fellows of the 
Society : — 
Maurice Lothian, Esq. 
John Maclaren, Esq. 
The following Donations to the Library were announced : — 
Abbe (Cleveland). Dorpat and Poulkova. Washington, 1867. 
8vo. — From the Author. 
Baars (Herman). Berelning om den Internationale Fiskerind- 
stilling i Boulogne - sur - Mer, 1866. 12ino. — From the 
Author. 
Les Peches de la Norwege. Boulogne-sur-Mer, 1866. 
8 vo. — From the Author. 
Bigsby (John J.), M.D., F.G.S. Flora and Fauna of the Silurian 
Period, with Addenda. London, 1868. 4to. — From the 
Author. 
Broch (Dr 0. J.). Traite Elementaire des Fonctions Elliptiques. 
Fasc. II. Christiania, 1867. 8vo. — From the Author. 
Brown (Robert). Das Innere der Vancouver-Insel. 4to. Being 
a German translation of his paper. — Fro m Author. 
Castello de Paiva (Barone de). Monographia Molluscorum Terres- 
trium, Fluvialium, Lacustrium, Insularium Maderensium. Oli- 
sipone, 1867. 4to — From the Author. 
Cohen (Henri). Description des Medailles Grecques, Romaines, 
etc. Paris, 1869. 8vo. — From the Author. 
