*30 Eoyal Society: Prof. Faraday*s Experimental 



Researches in Electricity," Thirteenth Series, by Michael Faraday, 

 Esq., D.C.L., F.R.S., &c., was commenced. 



March 22. — A paper was read, entitled, " Description of a 

 new Tide- Gauge, constructed by T. G. Bunt, and erected on the 

 Eastern bank of the River Avon, in front of the Hotwell House, 

 Bristol, in 1837." Communicated by the Rev. William Whewell, 

 M.A., F.R.S. 



The principal parts of the machine here described, are an eight- 

 day clock, which turns a vertical cylinder, revolving once in twent}'- 

 four hours ; a wheel, to which an alternate motion is communicated 

 by a float rising and falling with the tide, and connected by a wire 

 with the wheel which is kept constantly strained by a counterpoise ; 

 and a small drum on the same axis with the wheel, which by a sus- 

 pending wire communicates one 18th of the vertical motion of the 

 float to a bar carrjdng a pencil which marks a curve on the cylinder, 

 or on a sheet of paper wrapped round it, exhibiting the rise and fall 

 of the tide at each moment of time. The details of the mechanism, 

 illustrated by drawings, occupy the whole of this paper. 



A paper was also read, entitled, " On the R6gar or Black Cotton 

 Soil of India," by Capt. Newbold, Aide-de-Camp to Brigadier-Ge- 

 neral Wilson. Communicated by S. H. Christie, Esq., M.A., 

 Sec. R.S. 



The author states that the Regar of India is found, by chemical 

 analysis, to consist of silica, in a minute state of division, together 

 with lime, alumina, oxide of iron, and minute portions of vegetable 

 and animal debris. Hence it is usually considered as having been 

 formed by the disintegration of trap rocks : the author, however, 

 after examining its numerous trap dykes traversing the formation of 

 the ceded districts, which he found invariably to decompose into a 

 ferruginous red soil, perfectly distinct from the stratum of black 

 regar through which the trap protrudes, was led to regard this opi- 

 nion of its origin as erroneous : and from the circumstance of its 

 forming an extensive stratum of soil covering a large portion of the 

 peninsula of India, he believes it to be a sedimentary deposit from 

 waters in a state of repose. 



Specimens of basaltic trap and of the Regar soil were transmitted 

 to the Society by the author, for the purpose of analysis. 



The reading of a paper, entitled, "Experimental Researches in 

 Electricity," Thirteenth Series, by Michael Faraday, Esq,, D.C.L., 

 F.R.S. , &c., was resumed but not concluded. 



March 29, 1838. — The reading of a paper, entitled, "Experi- 

 mental Researches in Electricity," Thirteenth Series, by Michael 

 Faraday, Esq., D.C.L., F.R.S., was resumed but not concluded. 



April 5, 1838. — The reading of a paper, entitled, "Experimental 

 Researches in Electricity," Thirteenth Series, by Michael Faraday, 

 Esq., D.C.L., F.R.S., was resumed and concluded. 



The author, in this paper, pursues the inquiry into the general 

 differences observable in the luminous phenomena of the electric 

 discharge, according as they proceed from bodies in the positive or 

 the negative states, with a view to discover the cause of those dif- 



