CONTENTS OF VOL. XLII. 



(FOURTH SERIES.) 



NUMBER CCLXXVII.— JULY 18/1. 



Page 

 M. L. A. Colding on the Universal Powers of Nature and their 



Mutual Dependence 1 



M. L. Schwendler on an Arrangement for the Discharge of long 



Overland Telegraph Lines , 20 



Prof. Challis on the Application of a new Integration of Dif- 

 ferential Equations of the Second Order to some unsolved 



Problems in the Calculus of Variations 28 



Messrs. G. J. Stoney and J. E. Reynolds's Inquiry into the 

 Cause of the Interrupted Spectra of Gases. — Part II. On the 



Absorption-spectrum of Chlorochromic Anhydride 41 



Mr. S. T. Preston on the Direct Conversion of Dynamic Force 



into Electricity 53 



Prof. W. A. Norton on the Physical Constitution of the Sun. . 55 

 Mr. J. C. Douglas on Increasing the Rigidity of long, thin 



Metallic Pointers, Magnetic Needles, &c 67 



Notices respecting New Books : — 



Mr. J. A. S. Rollwyn's Astronomy Simplified for General 

 Reading, with numerous new Explanations and Disco- 

 veries in Spectrum Analysis, &c 69 



Proceedings of the Royal Society : — 



The Rev. S. J. Perry's Results of Seven Years' Observa- 

 tions of the Dip and Horizontal Force at Stony hurst 

 College Observatory, from April 1863 to March 1870 .. 71 

 Mr. E. J. Stone on an approximately Decennial Varia- 

 tion of the Temperature at the Observatory at the Cape 



of Good Hope between the years 1841 and 1870 72 



MM. Wolf and Fritz on Sun spots 75 



Proceedings of the Geological Society : — 



Prof. A. C. Ramsay on the Physical Relations of the New 



Red Marl, Rhsetic beds, and Lower Lias 76 



Mr. J. W. Hulke on a large Reptilian Skull from Brooke, 



Isle of Wight 77 



Mr. J. W. Judd on the Punfield Formation 77 



Mr. W. S. Mitchell on the Denudation of the Oolites of 



the Bath district 78 



On the Microscopic Structure of Hail, by Paul Reinsch 79 



