IV CONTENTS OF VOL. X. FIFTH SERIES. 



NUMBER LX.— AUGUST. 



Page 

 Lord Rayleigh on the Resultant of a large Number of Vibra- 

 tions of the same Pitch and of arbitrary Phase 73 



Mr. W. Baily on the Vibrations of a Film in reference to the 



Phoneidoscope. (Plate I.) 79 



Dr. A. E. Leeds on the Laws governing the Decomposition of 

 Equivalent Solutions of Iodides under the Influence of 



Actinism 89 



Sir William Thomson on Vortex Statics 97 



Sir William Thomson on Gravitational Oscillations of Eotating 



Water 109 



Lord Rayleigh on the Resolving-nower of Telescopes 116 



Mr. H. Hennessy on the Eigure of the Planet Mars 119 



Prof. E. Wiedemann on a Means to determine the Pressure 

 at the Surface of the Sun and Stars, and some Spectroscopic 



Remarks 123 



Mr, E. H. Liveing on a new Instrument for the Detection and 



Measurement of Inflammable Gas in Mines. (Plate II.) . . 126 

 Proceedings of the Geological Society : — 



Mr. E. C. J. Spurrell on the Discovery of the Place where 



Palaeolithic Implements were made at Crayford 131 



Mr. W. Keeping on the Geology of Central Wales 131 



Mr. A. H. Stokes on the Coal found at Siideroe 132 



Mr. E. Nolan on the Old Red Sandstone of the North of 



Ireland 133 



Messrs. Peach and Home on the Glaciation of the Orknev 



Islands 133 



An Application of Accidental Images, by J. Plateau, Member 



of the Royal Academy of Belgium 134 



On Boltzmann's Method for determining the Velocity of an 



Electric Current, by E. H. Hall 136 



On a new Eorm of Galvanometer, by L. Gostynski 138 



On a Digestive Eerment contained in the Juice of the Eig-tree, 



by M. Bouchut 139 



Observations on the Vapour-density of Iodiue, by M. Berthelot 140 



On the Density of the Vapour of Iodine, by L. Troost 141 



Note on a Demonstration- Differential Thermometer, by Henri 

 Dufour 143 



NUMBER LXL— SEPTEMBER. 



Mr. J. W. Clark on the Behaviour of Liquids and Gases near 



their Critical Temperatures. (Plate III.) 145 



Sir William Thomson on the Vibrations of a Columnar Vortex 155 

 Mr. H. M'Coll on the Diagrammatic and Mechanical Repre- 

 sentation of Propositions and Reasonings 168 



