280 



proceed from the region of the ** zona " ; and probably have their 

 origin in the cells by which the latter is surrounded. If so, the au- 

 thor thinks we cannot suppose them to arise in any other way than 

 that which, according to his observations, appears to be the universal 

 mode of reproduction ; namely, by division of the nuclei of the pa- 

 rent cells. Nor can we suppose that minuteness is any hinderance 

 to their subsequent increase by the same means. 



December 17, 1840. 

 The MARQUIS OF NORTHAMPTON, President, in the Chair. 

 The following communications were made to the Society, viz. 



1 . " Present state of the Diamond Mines of Golconda." By T. J. 

 Newbold, Esq., of the Madras Army, A.D.C. to Major- General 

 Wilson, K.B. Communicated by S. H. Christie, Esq., M.A., 

 Sec. R.S. 



The author gives an account of the tract of country in which the 

 diamond mines of Golconda are situated, and of the processes by 

 which the diamonds are obtained. The latter consist merely in 

 digging out the rolled pebbles and gravel, and carrying them to small 

 square reservoirs, raised on mounds, having their bottom paved with 

 stones, and then carefully washing them. Dry weather is selected 

 to carry on these operations, in order to avoid the inconvenience and 

 expense of draining. A description is then given of the mines of 

 BanaganpuUy, Munimudgoo, Condapilly, Sumbhulpoor, and Poonah 

 in Bundlekund. 



2. " Magnetic-term Observations made at Milan." By Professor 

 Carlini, Director of the Observatory at that place : also " Magnetic - 

 term Observations made at Prague." By Professor Kreil, Director 

 of the Observatory at that place. 



3. "On the Production of Heat by Voltaic Electricity." By J. P. 

 Joule, Esq. Communicated by P. M. Roget, M.D., Sec. R.S. 



The inquiries of the author are directed to the investigation of the 

 cause of the different degrees of facility with which various kinds of 

 metal, of different sizes, are heated by the passage of voltaic elec- 

 tricity. The apparatus he employed for this purpose consisted of a 

 coil of the wire, which was to be subjected to trial, placed in a jar 

 of water, of which the change of temperature was measured by a very 

 sensible thermometer immersed in it ; and a galvanometer, to indicate 

 the quantity of electricity sent through the wire, which was estimated 

 by the quantity of water decomposed by that electricity. The con- 

 clusion he draws from the results of his experiments is, that the ca- 

 lorific effects of equal quantities of transmitted electricity are pro- 



