On certain Questions relating to the Moon's Orbit. 429 



cannot allow to pass unnoticed. Mr. Thomson no longer ascribes 

 the discoveiy of the law, that the quantity of heat generated by 

 the Ley den jar is proportional to the square of the quantity of 

 electricity, to INlr. Joule, but claims it for Cuthbertson, from 

 whose experiments, he asserts, M. Becquerel had " quite ex- 

 plicitly enunciated" the law in 1835. I regret that the re- 

 mark of M. Becquerel has not been given completely, for if 

 this had been done I should have been spared the present 

 communication. The place in the original reads as follows : — 

 "Cuthbertson et autres physiciens qui ont mesure avec des 

 electrometres Paction calorifique produite par la decharge d'une 

 batterie, ont trouve qu'elle croissait a peu pres comme la carre 

 des charges des batteries pour certaines longueurs des lils. Cette 

 loi varie en outre suivant I'epaisseur des jarres qui composent la 

 batterie. Celles qui sont epaisses ont une puissance de fusion 

 moins grande." It is not necessary to be acquainted with the 

 experiments of Cuthbertson to see, from the tenour of the above, 

 that M. Becquerel speaks of fusion, and of fusion only. That, 

 however, by the well-known fusion experiments of Cuthbertson 

 and others, which I myself have discussed in a memoir upon the 

 same subject (PoggendorfF's Annalen, vol. Ixv. p. 497, translated 

 in the Scientific I\I:moirs), the law in question has been proved, 

 will scarcely be asserted by any man, even though he should not 

 be acquainted with the fact that in the case of fusion, besides 

 the heating, another electric action comes into play. 

 I have the honour to be. 



Your obedient Servant, 

 Berlin, May 11, 1854. P. RiESS. 



LXX. On certain questions relating to the Moon's Orbit. 

 By Professor Challis. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



I BEG of you the favour to make public the follomug state- 

 ment on a matter which nearly concerns my scientific credit. 

 In the communication which I made to the April Number of 

 the Philosophical Magazine on two new Theorems relating to 

 the ]\Ioon's Orbit, I stated that a paper containing the proofs of 

 these theorems had been read before the Cambridge Philosophical 

 Society. Ilavnig become aware that hesitation was felt on the 

 pai-t of the Council of the Society to order the printing of the 

 paper, on account of an adverse opinion formed of it by one or 

 both of the gentlemen to whom it was referred, I at once with- 

 drew it, with the view of relieving the Couiioil from the Jiecessity 

 of coming to a decision, and because I considered that my com- 

 munication to the Philosophical Magazine sufficiently secured 



