386 Linncean Society.— Geological Society. 



culations as superfluous, and recommends a repetition of the experi- 

 ments with the experience ah-eady gained, and in the same locahty. 



The Appendix to this paper by Mr. Airy contains the formulae 

 of computation used, and their apphcation to the observed cases. 

 The observations were made by the method of disappearances and 

 re-appearances, the vibrations being continued till the arc of vibra- 

 tion had become so small as to produce a complete obscuration of 

 the disk, for more than -tO" in some instances, and thus entailing 

 errors on the method of disappearances alone, which Mr. Airy cha- 

 racterizes as most enormous, as he also states to be, the interval be- 

 tween the disappearance on one side and the disappearance on the 

 other, as the arc of vibration diminishes. It therefore became ne- 

 cessary to find some rule for determining the exact time of coinci- 

 dence, which was found to be a mean of the first disappearance and 

 the last re-appearance, or that of the first re-appearance and last 

 disappearance ; or rather a mean of all these four times. Mr. Airy 

 next considers the correction depending on the arc of vibration, and 

 then, successively, the thermonietric and barometric corrections ; 

 and he finally states at length the analytical theory of them all. 



March 29. — Viscount Mahon, and the Rev. C. Mayo, were re- 

 spectively admitted Fellows of the Society. And the reading was 

 commenced of a paper On the compounds of chromium ; by Tho- 

 mas Thomson, M.D. F.R.S. 



LINNiEAN SOCIETY. 

 April 3, and April, 17. — The reading of Mr. W. S. MacLeay's 

 paper On the Birds of Cuba was continued on the above evenings. 



GEOLOGICAL SOCIETY. 



Feb. 16. — At the Anniversary Meeting of the Society, held this 

 day, the following gentlemen were elected Officers and Council for 

 the year ensuing. 



President: William HenryFitton, M.D. F.R.S. — Vice-Presidents: 

 Arthur Aikin, Esq. F.L.S.; John Bostock,M.D. F.R.S.; Rev.W.D. 

 Conybeare, F.R.S. ; Rev. Adam Sedgwick, F.R.S. Woodwardian 

 Professor, Cambridge. — Secretaries : W, J. Broderip, Esq. F.L.S. ; 

 R. I. Murchison, Esq. F.R.S. — Foreign Secretary: Henry Heu- 

 land,Esq. — Treasurer: John Taylor, Esq. F.R.S. — Council: Henry 

 Thomas De la Beche, Esq. F.R. & L.S. ; J. E. Bicheno, Esq. Sec, 

 L.S.; Davies Gilbert, Esq. M.P. V.P.R.S.; George Bellas Green- 

 ough, Esq. F.R. cS: L.S. ; John Frederick William Herschel, Esq. 

 Sec. R.S. ; Armand Levy, Esq. ; Charles Lyell, Esq. F.R.S. ; Wil- 

 liam Hasledine Pepys, Esq. F.R.S. ; Rev. John Honeywood Ran- 

 dolph ; Charles Stokes, Esq. F.R.S. &L.S. ; J. F. Vandercom, 

 Esq.; Henry Warburton, Esq. M.P. F.R.S.; Thomas Webster, 

 Esq. ; Thomas Young, Esq. 



March 2. — A paper was read, " On the volcanic district of Na- 

 ples;" by G. Poulett Scrope, Esq. F.G.S. F.R.S. 



In this paper the author purposes to confine himself to ageneral view 

 of the volcanic formation of this district, and to such observations as 

 have hitherto escaped notice, or on which he differs from other writers. 



At 



