VI CONTENTS OF VOL. XXX. FOURTH SERIES. 



Page 



On Newton's Rule for Imaginary Roots 363 



Prof. Wiedemann on the Magnetism of Salts of the Magnetic 



Metals 366 



Prof. Cayley on a Problem of Geometrical Permutation 370 



Proceedings of the Cambridge Philosophical Society : — 



Prof. De Morgan on a Theorem relating to Neutral Series 372 

 Prof. De Morgan on Infinity, and on the Sign of Equality. 373 

 Dr. Humphry on the question, " Is the Vertebral Theory 



of the Skull to be abandoned ? " 374 



Prof. De Morgan on the Early History of the Signs + 



and — 376 



Mr. A. Newton's " Notes on Spitsbergen " 376 



Mr. Todhunter on the Method of Least Squares 378 



Proceedings of the Geological Society : — 



Mr. J. Prestwich on the Raised Beach of Sangatte 378 



Messrs. C. Le Neve Foster and W. Topley on the Super- 

 ficial Deposits of the Valley of the Medway 379 



M. E. Lartet on Ovibos moschatus, Blainville 379 



Mr. J. W. Salter on some Additional Fossils from the 



Lingula-flags 380 



Mr. H. Woodward on the Discovery of a New Genus of 

 Cirripedia in the " Wenlock Shale of Dudley," and on 



some new species of Eurypterida 380 



Mr. H. Woodward on a new genus of Eurypterida from 



the Lower Ludlow Rocks of Leintwardine, Shropshire . 381 

 Captain H. Godwin- Austen on the Carboniferons Rocks of 



the Valley of Cashmere 381 



Mr. W. B. Dawkins on the Mammalian Remains found by 



E. Wood, Esq., near Richmond, Yorkshire 382 



On the Deportment of two Salts in Solution, by E. Gerland. . 382 

 On the General Existence of Copper in the Animal Kingdom, by 



G. L. Ulex 384 



Speculations upon a possible method of determining the Distance 



of certain Variably Coloured Stars, by Joseph Wharton. . . 386 

 On the Action of Light upon Sulphide of Lead, and its bearing 

 upon the preservation of Paintings in Picture- Galleries, by Dr. 



D. S. Price 389 



On the use of Magnesium as Electromotor Metal in Voltaic Ele- 

 ments, by M. Bultinck „,.-.. 390 



On the Inversion of the Spectra of Metallic Vapours, by Lothar 



Meyer 390 



Note on the Velocity of Sound, and on the Mechanical Energy 

 of Chemical Actions, by Dr. Schroder van der Kolk 391 



NUMBER CCV.— DECEMBER. 



Prof. Tyndall on Helmholtz's Lecture on Ice and Glaciers . . 393 

 Dr. Rankine on Thermodynamic and Metamorphic Functions, 

 Disgregation, and Real Specific Heat 407 



