49 



May 12. 



HIS ROYAL HIGHNESS THE DUKE OF SUSSEX, K.G., 

 President, in the Chair. 



Captain George William Manby was elected a Fellow of the So- 

 ciety. 



The following Presents were received, and thanks ordered for 

 them : — 



Roval Astronomical Society. Notices of Proceedings. Vol.2. Nos. 

 2 and 3. 8vo. 



— — Charter and Bye-Laws, 1831. 12mo. 



— Presented by the Society. 



The Edinburgh Journal of Science. No. 8. New Series, (i^pril 

 1831.) 8vo. — David Brewster, LL.D. F.R.S. 



Memoir of the Life and Scientific Labours of the Rev. William 

 Gregor, M.A. By John Ayrton Paris, M.D. F.R.S. 8vo. — J. G. 

 Children, Esq. Sec. R.S. 



Description of the Skeleton of the Fossil Deer of Ireland, Cervus 

 Megaceros. By John Hart, Esq. Second Edition, with an Ap- 

 pendix. Svo. — The Author. 



A Key to Bonnycastle's Trigonometry, Plane and Spherical ; con- 

 taining Solutions to all the Problems, with references. 8vo. By 

 Griffith Davies, Esq. — The Author. 



Recueil de Planches de Petrifications Remarquables. Par Leopold 

 de Buch. Premier Cahier. folio. — The Author. 



A paper was read, " On a peculiar class of Acoustical Figures ; 

 and on certain forms assumed by groups of particles upon vibra- 

 ting elastic surfaces." By Michael Faraday, Esq., F.R.S., M.R.I., 

 Corresponding Member of the Royal Academy of Sciences of Paris, 

 &c. 



When elastic plates on which sand has been strewed are thrown 

 into sonorous vibrations, the grains of sand arrange themselves in 

 lines which indicate the quiescent parts of the plate, and have been 

 called the nodal lines. This fact was discovered by Chladni, who 

 also observed that the minute shavings cut by the edge of a glass 

 plate from the hairs of the violin bow employed to produce the vi- 

 bration, collected together on those parts of the plate that were 

 most violently agitated, that is, at the middle of the lines of oscilla- 

 tion, or portions into which the plate is divided by the nodal lines. 

 The same phenomenon is exhibited by lycopodium, or any other 

 very light and finely divided powder. This subject was investi- 

 gated by M. Savart, who, in a paper read to the Royal Academy of 

 Sciences at Paris in the year 1817, endeavoured to account for this 

 latter class of phenomena by deducing from the primary divisions 

 of the parts of vibrating bodies, certain secondary modes of divi- 

 sion, comprising parts that remain horizontal during every stage of 



e2 



