1820.] Geological Society. 147 



barometer with the determination of Gen. Roy. In this case 

 some discrepancies were observed, which the author referred to 

 the difficulty of ascertaining the stations on account of the inde- 

 terminate form of the hill. 



At this meeting there was likewise read a short paper, entitled, 

 " Further Particulars respecting the Anatomy of the Dugong," 

 by Sir E. Home. This paper was intended as a supplement to 

 Sir Stamford Raffles's account of that animal, and contained a 

 few additional remarks. 



The titles of the following papers were read : 



" On the Compressibility of Water," by Jacob Perkins, Esq. 



" A Sketch of an Analysis and Notation appUcable to the 

 Estimation of the Value of Life Contingencies," by Benj . Gom- 

 pertz, Esq. 



" An Inquiiy into the Anatomy of certain Parts of the Globe 

 of the Eye, upon the Structure of which Anatomists have not 

 agreed in Opinion," by Arthur Jacob, M.D. 



" Various Astronomical Observations, accompanied by some 

 Tables," by Stephen Groombridge, Esq. 



" A Letter from M. Stocklar, For. M.R.S. to Dr. Young, on 

 some General Expressions for the Limits of Functions." 



The Society adjourned till November. 



GEOLOGICAL SOCIETY. 



June 16. — A paper entitled " Additional Remarks on Glen 

 Tilt," by Dr. M'Cullock, M.G.S. was read. 



A remarkable variety of limestone occurs among the micaceous 

 schist and gneiss which form the northern boundary of the Tilt, 

 and near to its junction with the Garry. It is of a laminated 

 structure, each lamina of calcareous matter being separated from 

 the next by one of mica, and rarely exceeding the 20th of an 

 inch in thickness. The laminag are perfectly flat and parallel. 



A more complete examination of the beds of yellow marble 

 described at p. 39 of the third volume of the Geological Trans- 

 actions, has shown that the predominant gneiss is of a white 

 colour intersected by numerous reticulating veins of a pale ochry 

 yellow. 



The white marble, mentioned at p. 50, has since been found in 

 its natural place between Tsalair and the Ward of Glen Fernat ; 

 another bed of the same nature exists in the hills that bound the 

 Tilt to the southward. A bed of white marble similar to that at 

 Gow's Bridge has been discovered in the hills that form the 

 south eastern boundary of the valley at a great distance from the 

 former, and with an immense series of quartz rocks interposed. 



Gneiss has not been observed among the strata lying upon 

 the granite of the southern side of the valley, but in the hills at 

 the northern side it occurs in considerable abundance, together 

 with quartz rock, micaceous schist, and varieties of hornblende 

 schist. 



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