800 Proceedings of the Cambridge Philosophical Society. 
May 21.— u On the Basaltic Dikes in the County of Dur- 
ham, and on the Great Basaltic Formations in Teesdale by 
the Rev. Professor Sedgwick, M. A. Fellow of Trinity College. 
May 22. — Being the Anniversary Meeting of the Society, the 
following officers were elected for the ensuing year : 
President,— The Very Rev. Dr Wood, Master of St John’s, and Dean of Ely. 
Vice-President, — Rev. T. Turton, B. D., Lucasian Professor of Mathematics. 
Treasurer,— Rev. B. Bridge, B. D., Fellow of Peterhousc, 
Secretaries J Rev ‘ G * Peacock ’ M * A -> Tutor of Trinity. 
’ ( J. S. Henslow, M. A., Professor of Mineralogy. 
Steward of the Reading-Room,— W. Whewell, M. A. Fellow of Trinity. 
Members of the Council, 
Rev. J. Cumming, M. A., Professor of Chemistry. 
Rev. S. Lee, M. A., Professor of Arabic. 
Rev. T. S. Hughes, B. D., Fellow of Emmanuel. 
Rev. T. Chevallier, M. A., Tutor of Cath-Hall. 
Rev. A. J. Carringham, B. D., Fellow of St John’s. 
Rev. A. Dickson, M. A., Fellow of Peterhouse. 
I JT. King, M. A., Tutor of Queen’s. 
A paper was read by W. Whewell, M. A. Fellow of Trinity 
College, on two mechanical problems. The first was the oscil- 
lation of a chain or string, suspended vertically, and slightly dis- 
placed. There are an infinite number of cases in which the 
chain can oscillate symmetrically, which are given by the roots 
of an equation of an infinite number of terms. Euler had 
found one of the roots of this equation. Mr W., by a particu- 
lar mode of approximation, has found values for all of them, 
and determined all the positions of the chain which give symme- 
trical oscillations. The other problem was that of the motion 
of a body oscillating, while it is drawn up uniformly; which has 
been attempted by some English mathematicians, and which is 
found, when solved approximately, to have some relations with 
the former problem of this paper. 
A communication of some Electro-Magnetic Experiments, by 
Gybbon Spilsbury, Esq. In repeating the experiments of Pro- 
fessor Cumming, on the different electric relations of iron and 
steel, copper and brass, &c., Mr Spilsbury found, that the gal- 
vanoscope was sensibly affected, not only when a metallic rod 
was placed in galvanic contact, with any alloy of the same 
metal, but when similar metallic alloys were presented to each 
other, provided they were of different dimensions. If two rods 
of steel, one being larger than the other, were immersed in an 
acid ; on completing the galvanic circuit, the effect on the 
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