IV CONTENTS OF VOL. XXXI. FIFTH SERIES. 



Page 



On Electrical Convection, by A. Eighi 74 



On the Photographic Action of Electromagnetic Waves, by 



Eranz von Dobrzynski 75 



Quantitative Photographic Investigation of Electrical Oscil- 

 lations, by J. Miesler 76 



On the Smallest Perceptible Visual Angle in the various parts 

 of the Spectrum, by W. Uhthoff 76 



NUMBEB CLXXXDL— EEBEUAEY. 



Mr. A. Schuster on the Elementary Treatment of Problems on 



the Diffraction of Light 77 



Lord Eayleigh on Pin-hole Photography. (Plate IV.) 87 



Mr. S. Tolver Preston on the Problem of the Behaviour of the 



Magnetic Eield about a Eevolving Magnet 100 



Mr. J. Swinburne on Alternate Current-Condensers 102 



Mr. H. M. Vernon on the so-called Meta-Elements 108 



Prof. Silvanus P. Thompson on the Use of Eluor-Spar in 



Optical Instruments , 120 



Mr. E. L. Mchols on the Alternating Electric Arc between a 



Ball and Point ..... 128 



Prof. J. J. Thomson on the Conductivity of Hot Gases .... 135 

 Mr. Shelford Bidwell on the Effect of Heat upon the Magnetic 



Susceptibility of Nickel 136 



Notices respecting New Books : — 



Mr. A. B. Basset's Elementary Treatise on Hvdrodynamics 



and Sound 138 



Eev. J. M. Eustace's Notes on Trigonometry and Loga- 

 rithms 140 



Scientific Papers of James Clerk Maxwell 141 



Proceedings of the Geological Society : — 



Mr. O. A. Derbv on Nepheline Eocks in Brazil. — II. 



The Tingua Mass 142 



Mr. J. W. Gregory on the Variolitic Diabase of the 



Eichtelgebirge 143 



Eev. E. Hill and Prof. Bonney on the North-west Eegion 



of Charnwood Forest 143 



Prof. T. G. Bonney on a Contact-Structure in the Syenite 



of Bradgate Park 144 



Dr. C. Callaway on the Unconformities between the Eock- 

 Systems underlying the Cambrian Quartzite in Shrop- 

 shire 145 



Changes of Volumes of Dielectrics, by D. Bos 146 



The Optical Useful Effect of Incandescent Lamps, by E. 



Blattner 147 



On the Conductivity of Snow, by S. A. Hjeltstrbin 148 



