27't Mr. J. Hogg and Sig. Tenore on the comparative Influence 



absolutely evanescent by hypothesis. As Mr. Moseley lias 

 endeavoured to strengthen his arguments on this matter by a 

 verification obtained from a different method of investigation 

 (page 199 et seq.), it becomes necessary for me to remark, that 

 no reliance can be placed upon it, for these two reasons : 



1st, It does not appear that the assumption of a point X, 

 about which the moments of the pressures upon A, B, C may 

 be equal, is a possible assumption. 



2ndly, Mr. Moseley shows that Sa — b—c = 0; and yet 



when, at the bottom of page 200, he arrives at the equation 



x q (3a — b— c) — 2.r a {b + ac — b c) = —abc, 



he altogether overlooks the circumstance that the first term 



is evanescent, and that, consequently, the value of x is 



— abc 



— r^ r— , which is not infinite. Wherefore, as Mr. Mose- 



ab+ac—uc 



ley's verification rests entirely upon x being infinite, it must 

 fall to the ground. 



As I am anxious not to extend this letter to an unnecessary 

 length, I shall not make any remarks upon Mr. Moseley's ap- 

 plication of his theory to the wedge and the arch ; for I have 

 not discovered in them anything which either militates against 

 my arguments, or goes to confirm the theory in question. 

 I have now, therefore, only to thank Professor Moseley for 

 his polite reply to my former observations, and to assure him 

 that as I write only for the investigation of truth, I shall feel 

 a pleasure in confessing my opinion wrong as soon as he has 

 satisfactorily answered the objections contained in this letter; 

 and I am sure that he will pardon the trouble I am causing 

 him, from a conviction that truth does not suffer, but gain, by 

 every examination to which it is submitted. 



I am, Gentlemen, yours, &c. 

 St. John's College, Cambridge, S. Earnshaw. 



March 8, 1834. 



XLVIII. On the Influence of the Climate of Naples upon the 

 Periods of Vegetation as compared with that of some other 

 Places in Europe. By John Hogg, Esq., M.A., F.L.S. 

 F.C.P.S., Sfc. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



T^HE geography of plants has of late years become a new 



A subject of great interest to the naturalist, and is at the 



present day esteemed a most important and useful branch of 



natural science. Linnaeus may be said to have first called the 



