CONTENTS OF VOL. XL. 



(FOURTH SERIES.) 



NUMBER CCLXIV.— JULY 1870. 



Page 



Mr. J. Ball on the Cause of the Descent of Glaciers 1 



Archdeacon Pratt's Reply to M. Delaunay's objection to the late 

 Mr. Hopkins's Method of determining the Thickness of the 

 Earth's Crust by the Precession and Nutation of the Earth's 



Axis 10 



Prof. E. Edlund on the Path of Electrical Induction- and Dis- 

 junction-Currents through Gases of various Densities, and 



between Poles of different shapes 14 



Mr. A. S. Davis on a possible Cause of the Bright Line observed 



by M. Angstrom in the Spectrum of the Aurora Borealis . . 33 

 Mr. R. Moon on the Solution of Linear Partial Differential 

 Equations of the Second Order involving two Independent 



Variables 35 



Mr. S. E. Phillips on a Simple Method of Constructing high 



Electrical Resistance 41 



Prof, von Bezold's Researches on the Electrical Discharge .... 42 

 The Rev. J. M. Heath on the Interchangeability of Heat and 



Mechanical Action 51 



Proceedings of the Royal Society : — 



Mr. Warren De La Rue, Dr. Balfour Stewart, and Mr. B. 

 Loewy on the Positions and Areas of the Spots observed 

 at Kew during the years 1864-66, also the Spotted Area 

 of the Sun's visible disk from the commencement of 1 832 



up to May 1868 53 



Mr. H. T. Brown on the Estimation of Ammonia in Atmo- 

 spheric Air , 54 



Mr. H. E. Roscoe and Dr. T. E. Thorpe on the Relation 

 between the Sun's Altitude and the Chemical Intensity 



of Total Daylight in a Cloudless Sky 56 



Prof. C. Piazzi Smyth on Supra-annual Cycles of Tempe- 

 rature in the Earth's Surface-crust 58 



The Rev. S. Haughton on the Constituent Minerals of the 

 Granites of Scotland, as compared with those of Donegal. 59 



Mr. H. E. Roscoe on Vanadium 62 



Proceedings of the Geological Society : — 



Prof Huxley on Hypsilophodon, a new Genus oiDinosauria 68 

 Prof. Huxley on the Affinity between the Dinosaurian Rep- 

 tiles and Birds 69 



Prof. Huxley on the Dinosauria of the Trias 70 



