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 “ Mémoires de Y Académie Royale des Sciences de YInstitut 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 phe- 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 phenomena which may occur at the instant of incipient molecular attraction, and which become masked by the more general effect of the transfer of the elements when powerful electric currents are employed, it was necessary to sub- stitute for these currents of very low tension[1]. 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 crystals 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 majority had only been recomposed in an amorphous state. In 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 xxxiy. p. 152. Mémoire In a J’Académie Royale des Sciences, &c., 21 Aout, 1826.
