410 



a grain might arise from this circumstance alone ; setting aside a 

 number of other particulars that require minute attention, and 

 which do not seem to have been attended to in former experiments 

 of this kind. In fact, as Professor Schumacher remarks, though 

 we have thus five different pounds in excellent preservation, and com- 

 pared with the lost standard, with the greatest care and the best 

 instruments, though the number of these comparisons exceeds 600, 

 yet there still remains an uncertainty as to its real weight; and this 

 solely on account of its specific gravity and expansion not being 

 known. And, he adds, that it is to be hoped that no pound will in 

 future be declared a legal standard unless these elements (the know- 

 ledge of which is indispensable even for a single comparison with a 

 good balance) are previously determined with the greatest possible 

 precision. 



Besides the account of these numerous weighings, which are 

 stated in detail, Professor Schumacher has given various formulae 

 and tables which will be found of great use and application in any 

 future experiments of a like kind that may be undertaken. 



13. " On the Application of a New Principle in the Construction 

 of Voltaic Batteries, by means of which an equally powerful current 

 may be sustained for any period required ; with a description of a 

 sustaining battery recently exhibited at the Royal Institution." By 

 Frederick W. Mullins, Esq., M.P., F.S.S. Communicated by 

 N. A. Vigors, Esq., F.R.S. 



The method resorted to by the Author for obtaining a continu- 

 ous voltaic current of equal intensity, is the same in principle as 

 the one employed by Professor Daniell, and described by him in 

 his paper recently presented to the Royal Society, and published 

 in the Philosophical Transactions ; namely, the interposition of a 

 thin membrane between the two metals in the voltaic circuit, so as 

 to allow of the separation of the different fluids applied respectively 

 to each metal : the fluid in contact with the zinc being a mixture 

 of diluted sulphuric and nitric acids ; and that in contact with the 

 copper being a solution of sulphate of copper. The author re- 

 serves for a future paper the details of the results he has obtained, 

 with regard to the relations between the intensity of effect, and the 

 extent and disposition of the metallic surfaces : but states that he 

 has obtained powerful electric action by bringing the membrane 

 into contact with the zinc; the latter having no acid applied to it, 

 and the only fluid employed being the solution of sulphate of cop- 

 per. 



14. Anonymous Essay, entitled "Scoperta della Causa Fisica del 

 Moto." Presented to the Royal Societv, with a view to obtaining 

 one of the Royal Medals for 1836. 



The Author commences by an historical review of the opinions 

 of almost every philosopher, both ancient and modern, who has 

 treated of the subject of motion, from Pythagoras to Le Sage : and 

 proceeds to state his own ideas relating to the cause of motion.. 



