1818.] Scientific Intelligence. 153 



which they pass. To this cause may probably be ascribed the 

 different qualitities of the copper obtained from the Ecton mine, 

 and the mines of Cornwall. I am, Sir, 



Your obedient servant, 



13, Tavistock-street, Bedford-square, Dec. 10. ROBERT BAKEWELL. 



III. Third Volume of the Memoirs of the Society of Arcueil. 

 In consequence of the copy of this work, from which the 

 editors took their list of its contents, being accidentally imperfect, 

 they omitted the last article, which is a notice by M. Berthollet 

 on the decomposition of the oxymuriatic acid. It consists of a 

 short paper, in which this celebrated chemist renounces his 

 former hypothesis respecting the composition of this acid, as 

 consisting of muriatic acid and oxygen, and adopts that of its 

 being a simple substance, which forms muriatic acid by being 

 united to hydrogen. 



IV. Civil Engineers. 

 A Society has recently been instituted in London by some 

 young men following the profession of civil engineers, for the 

 purpose of mutual communication on the many important topics 

 immediately, or more remotely, connected with their professional 

 pursuits. The principle of their association is the diffusion of 

 useful knowledge among all the members ; on which account the 

 Society is restricted to practical engineers, and to such students 

 of general science as have especially directed their attention to 

 those subjects which particularly concern the civil engineer. 



The meetings are held once a week during the winter season j 

 business commences with the reading of an original essay, to 

 which succeeds the discussion of a topic previously agreed 

 upon at a former meeting : information relative to projects, 

 inventions, public works in progress, &c. closes the sitting. A 

 Society so constituted, and sustained with spirit, cannot but 

 prove of great advantage, both to the individual members, and 

 to the public at large. 



V. Astronomy . 



M. Biot has been appointed, by the Institute of France, to 

 visit this country, in order to unite with the gentlemen who 

 conduct the Trigonometrical Survey of Great Britain, in making 

 astronomical and other observations, at or near the northern 

 extremity of the British Isles. Dr. Olinthus Gregory, of the 

 Royal Military Academy, was associated with them for the same 

 purpose. 



In the months of May and June, M. Biot, assisted by Captain 

 R. Mudge, a son of Colonel Mudge, made experiments at 

 Leith Fort, on the length of the seconds' pendulum. The appa- 

 ratus employed is of the kind recommended by Borda for that 

 purpose, with slight modifications. When the experiments and 

 connected astronomical observations at Leith were terminated) 



