[ 106 ] 



XXI. Note to Mr. Hennessy's Paper on the Connexion be- 

 tween the Rotation of the Earth and the Geological Changes 

 of its Swface*. 



HPHE values of I x and K must be altered, as some incorrect 

 *■ assumptions were made in obtaining them. This alte- 

 ration will produce no changes in the general conclusions 

 which have been arrived at. 



The method for obtaining the moment of inertia of a solid 

 of revolution contained in equation (3.), appears to have been 

 inapplicable to the case of the internal spheroid of the earth 

 from the nature of the expression for p. The expression for 

 the earth's moment of inertia, which is used for obtaining the 

 theoretical coefficients of precession and nutation, is, however, 

 adapted to our purpose. In this case we havefj 



'.=IK?) 4 {(M!)>v^-K*h 



When this value of K is substituted in (19.), that resulting 

 for P will evidently be less than what has been already found, 

 and it will give an amount of denudation of the earth's sur- 

 face still more within the limits of geological observations 

 than that which has been previously obtained. 



H. Hennessy. 



XXII. Letter to Henry Lord Brougham, F.R.S., fyc., con- 

 taining Remarks on certain Statements in his Lives of Black, 

 Watt and Cavendish. By the Rev. William Vernon Har- 

 court, F.R.S. fyc. 



My dear Lord, 

 |Na volume of biography which you have lately published, 

 -*- I perceive that you have reprinted your contribution to 

 M. Arago's historical notice of W T att, in which the distin- 

 guished author attempted to transfer to the subject of his 

 eloge the credit of a celebrated chemical discovery, hitherto 

 by the common consent of chemists attributed to Cavendish. 

 Your personal challenge to myself would not have moved 

 me to enter again on a question which I scarcely think open 

 to dispute since the publication of the fac-similes of Caven- 

 dish's original notes of that discovery, in the Transactions of the 

 British Association for the Advancement of Science, had I not 



* Phil. Mag. vol. xxvii. p. 376, November 1845. 

 f Airy's Tracts, Precession and Nutation, Art. 43. 



