162 Prof. Faraday on Regelation, 



which, however, may be due to his registering days as rainy on 

 which there was a fall of local mist or mizzle — legeres bruines. 

 {Annuaire, 1825, p. 167.) 



I may mention in conclusion, that there appears to be much 

 in the chapters relating to the subject in this second volume to 

 countenance the belief that the moon's surface radiates heat un- 

 equally ; so that it is perhaps to the different extent of the ab- 

 sorbing surfaces, and the length of time during which, at the 

 several phases, they are exposed to the solar rays, that one may 

 ascribe the difference in the effects which have been noticed. 

 It is evident that the influence must vary with the moon's posi- 

 tion; and it may be further subject to other changes, for which 

 the discoveries of M. Niepce de St. Victor and — I venture to 

 add (from the frequency of storms at certain periods of the 

 moon's age, and the suclden nature of other phsenomena) — the 

 experiments of electricians will possibly afford an explanation. 



XXIV. On Regelation, and on the Conservation of Force. 

 By Professor Faraday. 



[The volume of reprinted ' Experimental Researches in Che- 

 mistry and Physics,^ by Prof. Faraday, which has just been 

 published, contains the following new matter in relation to the 

 above subjects. We think it expedient to transfer it to our pages.] 



On Regelation. 



THE subject of regelation has of late years acquired very 

 great interest through the experimental investigations of 

 Tyndall, J. Thomson, Forbes and others, and in its present state 

 will perhaps justify a few additional remarks on my part as to the 

 cause. On the first observation of the effect eight years ago, 

 I attributed it to the greater tendency which a particle of fluid 

 water had to assume the solid state, when in contact with ice 

 on two or more sides, above that it had when in contact on one 

 side only. Since then Mr. Thomson has shown that pressure 

 lowers the freezing-point of water*, and has pointed out how 

 such an effect occurring at the places where two masses of ice 

 press against each other, may lead first to fusion and then 

 union of the ice at those places, and so he explains the fact of 

 regelation. Prof. J. D. Forbesf does not think that pressure 

 causes regelation in this manner, though it favours it by moulding 

 ■the touching surfaces to each other. He admits Person's view 



* Belfast Society Proceedings, December 2, 1857. 



t Royal Society Edinburgh Proceedings, April 19, 1858. 



