394 Foreign Literature and Science. 



detail of the proceedings which furnished them, because if, 

 on the other hand, we consider them as sufiicient to excite 

 the interest of chemists in a plant so eminently useful as 

 the hop ; on the other, the various labors which we have 

 cited, still leave much to be desired. 



34. Electro-Magnetism. — M. Assiot, Professor of Natural 

 Philosophy at Toulouse, states an instance in which, during 

 a heavy thunder-storm in that city, on the 22d of June last, 

 a metallic tube that extended from the top of the house to 

 a well or cistern, served as the channel of a heavy discharge 

 of the electric current. The tube was much rent, and orh- 

 er damage sustained by the house, which was a small one, 

 and contained fourteen or fifteen persons, none of whom 

 were injured. The magnetic effects of the stroke were the 

 most remarkable. A spike which the fluid met in its way, 

 was sufliciently magnetised to lift a table knife, and was 

 used in magnetising other things. A tailor's boy, at the mo- 

 ment of the explosion, was smoking his pipe, with the back of 

 his chairleaningagainst a post near the conducting tube ; he 

 experienced no disturbance, but was greatly surprised on 

 the next Monday, in taking his needle-case out of his pock- 

 et, to find that the needles were so magnetised that seven 

 or eight of them would hang together in a chain. Another 

 case, placed on the chimney, twenty feet from the tube, 

 and containing five needles, was also strongly magnetised. 

 M. Assiot says that he shewed those good tailors who brought 

 him their needles, that two or three discharges from a sin- 

 gle jar through a wire wrapt spirally round a tube, would 

 produce the same efTects upon the needles it contained, and 

 that evidently without their forming part of the current. 



35. Velocity of Sound. — A very careful experiment was 

 made on the 21st and 22d of June last, at Paris, by order 

 of the Board of Longitude, in order to solve this problem 

 with greater precision than heretofore. The experiment- 

 ers were Humbold,Gay Lussac, Bouvard, Prony,Mathieu and 

 Arago. The former three stationed themselves at Montlhery, 

 and the latter three at Ville-Juif, two situations distant from 

 each other, by the most careful geographic measurements, 

 9549.6 toises. The experiments were performed in the 

 night, by means of two six pounders, one at each station. 



