476 Proceedings of Learned Societies. 



ture. Perhaps the new series of the Gentleman's Magazine ■will fill 

 this void. 



One of the bronze swords, of which so much has been said of 

 late, has been recently found near Rothbury, in the centre of Nor- 

 thumberland. It was buried in debris at the foot of a steep moor- 

 land hill, abounding in remains of roads, camps, etc., of apparently 

 early date. T, W. 



PROCEEDINGS OF LEARNED SOCIETIES, 



BY W. B. TEGETMEIER. 



GEOLOGICAL SOCIETY.— Nov. 22. 



Selenite Impressions in the London Clay. — Mr. P. Martin 

 Duncan read an interesting paper on the Impressions of Selenite in 

 the Woolwich Beds and London Clay. 



The spaces formerly occupied by Crystals of Selenite occur in 

 the Woolwich Beds, near Mottingham, Kent, and in the unfossili- 

 ferous London Clay of Tendring Hundred. Mr. Duncan described 

 the various facts bearing on the question, including the conditions 

 under which the beds were deposited, their chemical composition, and 

 the mineral condition of the fossils, and discussed the explanations that 

 could be suggested to account for the formation and subsequent 

 disappearance of the crystals. He came to the conclusion that the 

 mineral had resulted from the action of sulphuric acid, contained in 

 percolating water, on pre-existing carbonate of lime, the sulphuric 

 acid having been formed by the oxidation of sulphuretted hydrogen, 

 by the oxygen evolved from the decomposing vegetable remains 

 occurring in the Plant-beds intercalated in the strata containing 

 these Selenite-spaces. The hydro-carbons resulting from the same 

 decomposition would in solution be sufficient to produce the decom- 

 position of the Selenite. Mr. Duncan mentioned that the occurrence 

 of Selenite in a deposit must be held to prove the former existence 

 of organisms in it, and the removal of the Selenite to be equivalent 

 to the loss of the evidence of such existence ; consequently, there can 

 be no reason why the purest Clay-slate may not have been once as 

 fossiliferous as the Woolwich Beds. 



GEOGRAPHICAL SOCIETY.— Dec, 11. 



Discoveries, Madagascar. — Captain W. Rooke communicated an 

 account of a boat journey along the Coast Lakes of East Madagascar, 

 having heard, whilst at Mauritius in 1864, that the chain of lakes 

 south of Tamatave, in Madagascar, might be traversed for several 

 hundred miles in a boat sufficiently light to be carried over the 

 short portages, he determined to attempt their exploration. He 

 had a boat constructed especially for the journey, and, with three 



