22 



between the brass mark fixed by Capt. Lloyd on the north-east 

 landing stairs of the New London Bridge, and Mr. Bevan's mark on 

 the basement of the pilasters of the north-east landing stairs of 

 Waterloo Bridge, should be accurately determined, requested Sir 

 John Rennie to undertake this determination. Sir John Rennie has 

 reported to the Council that, after repeated trials, the greatest varia- 

 • tion of which did not exceed two-tenths of an inch, he found that 

 the mark on Waterloo Bridge is 3 feet and 1-65 inches above that 

 on New London Bridge. 



The Council have awarded the Copley Medal of this year to M. 

 Becquerel for his various Memoirs on the subject of Electricity, 

 published in the " Memoires del' Academic Royale des Sciences de 

 ITnstitut de France", and particularly for those on the production of 

 Crystals of Metallic Sulphurets and of Sulphur, by the long-con- 

 tinued action of electricity of very low tension, and published in 

 the tenth volume of those Memoirs. 



Among those who have been engaged in investigating the phae- 

 nomena of electricity, M. Becquerel holds an eminent rank, and 

 the Memoirs of the Royal Academy of Sciences of Paris bear 

 ample testimony to the success which has attended his researches 

 in this department of science. He appears early to have been sen- 

 sible that, for the detection of pheenomena which may occur at the 

 instant of incipient molecular attraction, and w^hich become masked 

 by the more general effect of the transfer of the elements M hen 

 powerful electric currents are employed, it was necessary to sub- 

 stitute for these currents of very low tension*. Following out this 

 view, carefully adjusting the strength of the current to the power of 

 the affinities brought into action, he succeeded, by electric decom- 

 position, and by subsequent recomposition of the elements, in ob- 

 taining crj^stals of some of the metallic sulphurets, of sulphur, of 

 the iodurets of lead and copper, of the insoluble sulphates of lime 

 and barytes, of the carbonate of lead, and other substances, a few 

 of which had previously, by other means, been obtained crystallized, 

 but of which the great ma,jority had only been recomposed in an 

 amorphous state. Li the Memoirs to which the Council have par- 

 ticularly adverted in the award of the Copley Medal to M. Bec- 

 querel, he had especially in view to explain, by the agency of elec- 

 tricity of very low tension, continued for an indefinite time, the oc- 

 currence of crystallized substances in mineral veins. The suc- 

 cess with which his experiments were crowned in obtaining by 

 such means crystals of the metallic sulphurets and of other sub- 

 stances, perfectly resembling those found abundantly in mineral 

 veins, is favourable to the correctness of the views he had enter- 

 tained ; and these views derive additional support from the results 

 obtained by others, in perfect accordance with his own, by means 

 differing from those he employed, but involving precisely the same 

 principles. Mr. Fox, in his experiments, which appear to have been 



* Annales de Chimie, tome xxxiv. p. 152. Memoke lu a rAcadeinie Royale 

 des Sciences, &c., 21 Aout, 1826. 



