CONTENTS OF VOL. XLVIL 



(FOURTH SERIES.) 



NUMBER CCCIX.— JANUARY 1874. 



Page 

 Mr. J. T. Buchanan on an Apparatus for Gas-analysis. 



(With a Plate.) 1 



M. H. Herwig on the Disintegration of the Electrodes in the 



Galvanic Arc of Light 6 



Prof. Challis's Theory of the Source of Terrestrial Magnetism. 14 



Mr. R. S. Brough on Wheatstone's Bridge 22 



Prof. Challis's further Discussion of the Analytical Principles 



of Hydrodynamics, in Reply to Mr. Moon 25 



M. A. F. Sundell on the Electromotive and Thermoelectric 



Eorces of some Metallic Alloys in contact with Copper .... 28 

 Mr. S. Roberts on a simple Condensing Collector for Fric- 



tional Electrical Machines 49 



Prof. W. E. Barrett on the Molecular Changes that accom- 

 pany the Magnetization of Iron, Nickel, and Cobalt 51 



Notices respecting New Books : — 



Mr. J. M. Wilson's Elementary G-eometry 56 



Proceedings of the Royal Society : — 



Dr. J. H. Gladstone and Mr. A. Tribe on an Air-Battery. 61 

 Mr. 0. Reynolds on the Condensation of a Mixture of 



Air and Steam upon Cold Surfaces 67 



Proceedings of the Geological Society : — 



Mr. S. Sharp on the Oolites of Northamptonshire. — 



Part II 74 



On some Phenomena of Illumination, by A. Lallemand .... 77 

 On a Process for verifying the Nodes in a Sounding Pipe, by 

 M. Bourbouze 80 



NUMBER CCCX.— FEBRUARY. 



Lord Rayleigh on the Manufacture and Theory of Diffraction- 

 gratings 81 



Mr. 0. Heaviside on Wheatstone's Bridge 93 



Mr. J. Croll on the Physical Cause of Ocean-currents 94 



Prof. W. H. Miller on Quartz, Ice, and Karstenite 122 



Prof. E. C. Pickering's Measurements of the Polarization of 

 the Light reflected by the Sky and by one or more Plates of 

 Glass 127 



