CONTENTS OF VOL. IX. 



(FIFTH SEEIES). 



NUMBEE LIIL— JANUAEY 1880. 



M. G. "Wiedemann on Torsion. (Plate I.) 1 



Frederick Guthrie on certain Vibrations of Solids. (Plates II. 

 & III.) 15 



Prof. Challis on Newton's " Eegula Tertia Philosophandi." . . 21 

 Prof. A. W. Eiicker on a Suggestion as to the Constitution of 



Chlorine, offered by the Dynamical Theory of Gases c 35 



Lord Eayleigh's Investigations in Optics, with special refer- 

 ence to the Spectroscope 40 



Mr. W. H. Walenn on a Method of Checking Calculations . . 56 

 Mr. J. H. Poynting on the Graduation of the Sonometer .... 59 

 Notices respecting New Books : — ■ 



Mr. J. E. Capron's Aurorae ; their Characters and Spectra 65 



M. G. Plante's Eecherches sur l'Electricite 70 



Proceedings of the Geological Society : — 



Mr. E. Mallet on the probable Temperature of the Pri- 

 mordial Ocean of our Globe 72 



Mr. J. A. Phillips on the Concretionary Patches and Frag- 

 ments of other Eocks sometimes contained in Granite 72 

 The Eev. G. Blencowe on certain Geological Facts wit- 

 nessed in Natal and the Border Countries during nine- 

 teen years' residence 73 



Dr. C. Callaway on the Gneissic and Granitoid Eocks of 



Anglesey and the Malvern Hills 73 



Prof. T. G. Bonney's Petrological Notes on the Neigh- 

 bourhood of Loch Maree 74 



Lecture Experiments in Acoustics, by Professor Silvanus P. 



Thompson 75 



On a new Standard of Light, by Prof. J. W. Draper 76 



On the Passivity of Iron, by L. Varenne 76 



An Experiment on Sulphur, by Dr. Theodor Gross 79 



NUMBEE LIV.— FEBEUAEY. 



Mr. L. Fletcher on the Dilatation of Crystals on Change of 



Temperature 81 



M. G. Wiedemann on Torsion 97 



