30 



sulphate of soda, coloured with syrup of violets, and inverted in a 

 cup containing the same liquid. A similar wire in another tube, also 

 filled with the coloured solution, was placed in communication with 

 the earth, and the fluids in each made to communicate by a bent 

 glass tube passing from one cup to the other. The result of the 

 experiment was, that hydrogen gas and alkali were developed in the 

 first tube, and oxygen gas and acid in the latter. 



The reading of a Paper, entitled, " An Account of Operations 

 carried on for ascertaining the Difference of Level between the River 

 Thames^ at London Bridge and the Sea: and also for determining the 

 Height above the Level of the Sea, &c.of intermediate points passed 

 over between Sheerness and London Bridge." By John Augustus 

 Lloyd, Esq. F.R.S. ; — was commenced. 



March 3. 



HIS ROYAL HIGHNESS THE DUKE OF SUSSEX, 

 President, in the Chair. 



The Rev. Robert Walker, M.A. was elected a Fellow of the So- 

 ciety. 



The following Presents were received, and thanks ordered for 

 them : — 



Illustrations of Indian Zoology. Part V. Folio. — Presented by John 

 E. Gray, Esq. 



Illustrations of Mr. Cooper's Surgical Dictionary. Parts IV., V., 



and VI. 8vo.— W. P. Cocks, Esq. 

 Notice of the Proceedings of the Geological Society. No. 18. 8vo. 



— The Society. 



The Philosophical Magazine and Annals of Philosophy. No. 51. 

 8vo. — The Editors. 



The Christian's Magazine, or Weekly Miscellany of Religious Es- 

 says, Anecdotes, Literature, Biography, Intelligence, and Poetry. 

 No. 1. 8 vo.—The Editor. 



National Portrait Gallery. No. 23. 8vo. — The Proprietors. 



A Vade Mecum of Morbid Anatomy, Medical and Chirurgical j with 

 Pathological Observations and Symptoms. Illustrated by up- 

 wards of Two Hundred and Fifty Drawings. By W. Money. 

 Second Edition. 8vo. — The Author. 



The reading of Mr. Lloyd's Paper was resumed and concluded. 



The author of this paper received directions from the Lords Com- 

 missioners of the Admiralty, in February 1830, at the suggestion 

 of the Royal Society, to survey the river Thames, with a view of 

 ascertaining the difference of level between certain parts of it and 

 the mean level of the sea near Sheerness. Having had experience, 

 while employed in a survey of the Isthmus of Darien, of the great 



