CONTENTS. 



Account of the late Earthquake at Demerara. By W. H. Camp- 

 bell, Esq. Communicated by M. Ponton, Esq., . • Page 1 

 On the Existence of an Electrical Apparatus in the Flapper Skate 



and other Rays. By Dr Stark, . . • ^ 



Observations on the Comet, visible now or lately in the Constella- 

 tion of the Whale. By C. Rumker, Esq. Communicated by Sir 

 T. M. Brisbane, Bart., . . • " -n-' 



On a Possible Explanation of the Adaptation of the Eye to Dis- 

 tinct Vision at Different Distances. By Professor Forbes, . b 

 Notice of an Ancient Beach near Stirling. By Charles Maclaren, 

 Esq., . • • • • • • ' 



Farther Remarks on the Electrical Organs of the Rays. By Dr 

 Stark, ...•••• ^ 



Observations on the same subject. By Professor Goodsir, • « 



Note on the Form of the CrystaUine Lens. By Professor Forbes. 

 Included in the former Abstract, . • ' a- 



On the Cause which has produced.-the Present Form and Condi- 

 tion of the Earth's Surface. By Sir George S. Mackenzie, Bart. , 9 

 Some Account of the Magnetic Observatory at Makerstoun, and of 

 the Observations made there. By J. A. Broun, Esq. Com- 

 _ municated by Sir T. M. Brisbane, Bart., . . .10 



fc Description of a Sliding Scale for FacUitating the Use of the Moist- 

 r bulb Hygrometer. By James Dalmahoy, Esq., • l^ 



Account of Experiments to Measure the Direct Force of the 

 Waves of the Atlantic and German Oceans. By Thomas 



t Stevenson, Esq. Communicated by David Stevenson, Esq., . 13 

 A Verbal Communication in regard to Chevalier's Experiments on 

 the Decomposition of certain Salts of Lead by Charcoal. By 

 Dr Traill, ..••••• 1^ 

 On a Peculiar Modification of the Doubly Refracting Structure of 

 Topaz. By Sir D. Brewster, K.H., . . .16 



Extracts from Letters to the General Secretary, on the Analogy 

 of the Structure of some Volcanic Rocks with that of Glaciers. 

 By C. Darwin, Esq., F.R.S. Specimens were exhibited. With 

 Observations on the same subject, made by Professor Forbes, 17 



Letter from Professor Gordon, of Glasgow, on the subject of the 



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