CONTENTS OF VOL. XVIII 



(FOURTH SERIES.) 



NUMBER CXVII.— JULY 1859. ^^^^ 



M. Plucker on the Action of the Magnet upon the Electric 



Current, from a new point of view r 'j-fc' " 



M. Pliicker on the Spectra in highly rarefied Gases of different 



kinds during the passage of the Electric Discharge 7 



Sir C. Lyell's Remarks on Professor C. Piazzi Smyth's sup- 

 posed proofs of the Submarine origin of TenerifFe and other 



Volcanic Cones in the Canaries • • 20 



Prof. Hennessy on the Thickness and Structure of the Earth s 



Crust ; : 22 



Prof. Volpicelli on Frictional Electricity ^o 



Dr. Gladstone and the Rev. T. P. Dale on some Optical Pro- 

 perties of Phosphorus •. • • ^^ 



Mr. A. Cayley on the Theory of Groups as depending on the 



Symbolic Equation 0»= 1 .—Part. Ill • ■ ■_ 34 



Prof. Miller on the employment of the Gnomomc Projection of 



the Sphere in Crystallography :VW-^i'-^ H 



Mr. J. Cockle on the Theory of Equations of the Fifth Degree, 50 



Messrs. W. H. Perkin and B. F. Duppa on lodacetic Acid 54 



Prof. Challis on the " Loss of half an undulation " in Physical 



Optics ^'^ 



Notices respecting New Books : — 



M. Delesse's Etudes sur la Metamorphisme des Roches . 61 

 The Rev. G. Salmon's Lessons Introductory to the Modern 



Higher Algebra ^' 



Proceedings of the Royal Society : — 



Dr. Hofmann on a New Class of Organic Bases 68 



Mr. W. J. M. Rankine on the Thermodynamic Theory of 



Steam-engines with dry saturated Steam 71 



Mr. C. V. Walker on Platinized Graphite Batteries .... 73 

 Proceedings of the Geological Society : — _ 



Messrs. J. Lancaster and C. C. Wright on the Sinking 



for Coal at the Shireoaks Colliery near Worksop, Notts. 77 

 Mr. A . R. C. Sel wy n on the Geology of Southern Australia. 7 7 

 On Thermography, or the Action of Heat considered as a means 

 of producing Images on Sensitive Paper, by M. Nifepce de 



Saint-Victor ; • ' ' Y ' •; ' "li ' " 



Notice of Traces of Eruptive Action in the Moon, by the Kev. 

 T. W. Webb ^" 



y. 



