288 
Communications made to the Society: 
(1) On the Equation which determines the form of the 
Strata in Legendre’s and Laplace's Theory of the 
Figure of the Earth, By I. Topnunter, M.A,, 
BE.RS., 
The object of this Memoir is to examine various investiga- 
tions which have been given respecting the equation which 
oceurs in the theory of the figure of the Earth considered as a 
heterogencous fluid, and from which it is inferred that the 
figure must be that of an ellipsoid of revolution. Especially 
the assumptions on which these investigations rest are discussed. 
The most general treatment which the equation has hitherto 
received is shewn to be unsound, Finally a new method is 
proposed, by which the required result is demonstrated with 
fewer limitations than have hitherto been employed. 
(2) Ona Cirque in the Syenite Hills in the Isle of Skye. 
By T. G. Bonnry, B.D. 
The Syenite hills occupy a portion of the eastern coast of 
Skye between the Liassic plain of the Strath (through which they 
have been extruded) and the great Trap district on the north. 
Though the date of this extrusion is uncertain, it is generally 
believed to have happened—as did that of the Trap—in Meio- 
cene times. The author stated that he had already described a 
number of cirques in districts of sedimentary rock (Quarterly 
Jounal of the Geological Society, Vol. xxvu. p. 812); he was 
now able to bring forward an instance from the crystalline 
rocks, in which good examples of such configurations, so far 
as his experience went, were rare. He considered that the 
cirques described near the heads of Alpine valleys could not 
be accounted for by upheaval, or marine erosion, and, by reason 
of the steepness of their cliffs and the limited space above 
