1824]. Scientific Intelligence. 469 



trie, published under the direction of Baron Ferassac, have announced 

 that, according to a discovery made by Col. Wright, the mercury of 

 the barometer, near the equator, rises and falls twice in 24 hours, 

 with so much regularity, that this instrument may almost be employed 

 as a measure of time. 



We beg those readers of the Annales de Chimie, &c. who think 

 that we communicate this discovery rather late, to remark that Goden, 

 Bouguer, and Laundamire, made the same discovery nearly a cen- 

 tury since ; that since these academicians all travellers to the equi- 

 noxial regions have been engaged on the subject; that M. Humboldt, 

 in 1807, published a very excellent work for the express purpose of 

 making known the true hours of the maxima and minima, and the ex- 

 tent of the oscillation (vide Geograph. des Plantes) ; that Lamanon in 

 the expedition under de Lapeyrouse, Horner in that of Krusenstern, 

 &c. &c. undertook similar researches ; that by means of the averages, 

 Duc-Lachapelle, at Montauban, M. Ramond, at Clermont-Ferrand, 

 the astronomers of the observatory at Paris, M. Marque Victor, at 

 Toulouse, &c. &c. have proved that this diurnal variation exists also 

 in our climates : lastly, that we never omit, in our accounts of meteo- 

 rological observations for the year, to give the amount of the daily 

 railing of the barometer, from nine o'clock in the morning till three 

 in the afternoon, and also of rising, which is evident between the last- 

 mentioned time, and nine at night. — (Annales de Chimie et de Phy- 

 sique, t. xxv. p. 334.) 



IV. On the Cause of the Rotatory Motion of Camphor in Water. 



(To the Editor of the Annals of Philosophy.) 

 SIR, Cambridge, May 7, 1824. 



The curious phenomenon of rotatory motion, which a particle of 

 camphor presents when placed on the surface of water, 1 have fre- 

 quently seen mentioned, but no where that I am aware of is there a cause 

 assigned. In making a few experiments upon the subject, I was led 

 to discover what I conceive to be the cause. It is a known law in 

 hydrostatics that if a body floats on a fluid, the centre of gravity of 

 the body and of the fluid displaced, must, when the body is at rest, be 

 in the same vertical line; otherwise a rotatory motion is given to the 

 body. In confirmation of this, if a perfectly smooth and square par- 

 ticle of camphor be placed on the surface of water, the camphor re- 

 mains at rest. But if an uneven particle be made use of, then the 

 centre of gravity of the body and of the water displaced are not in 

 the same vertical line, and a rotatory motion is produced. 



1 remain your's, &c. E. A. 



V. On the Transmission of Electricity through other Fluids. 



DEAR SIR, Charing Cross, May 12, 1824. 



Your number for April contains a letter from Mr. Woodward on 

 the transmission of electricity through other fluids; allow me through 

 the same channel to inform Mr. W. that the experiment of firing loose 

 gunpowder by passing the charge of a Leyden phial through tubes 

 filled with water, and also on the conducting power of alcohol, ether, 

 and acids, were made by a Mr. Lewthwaite, in May 1821, and are 

 published in the eleventh volume of the Institution Journal : it was 



