VI CONTENTS OF VOL. XLI. FIFTH SERIES. 



Note on Elementary Teaching concerning Focal Lengths, by 

 E. H. Barton 383 



Solution and Diffusion of Certain Metals in Mercury, by W. 

 J. Humphreys 384 



NUMBER, CCLIL— MAT. 



Dr. Laclislas Natanson on the Laws of Irreversible Pheno- 

 mena 385 



Dr. John Shields on a Mechanical Device for Performing the 



Temperature Corrections of Barometers 406 



Mr. J. H. Beeves on an Addition to the Wheatstone Bridge 



for the Determination of Low Resistances 414 



Mr. R. W. Wood on the Absorption Spectrum of Solutions 



of Iodine and Bromine above the Critical Temperature . . 423 

 Dr. G. A. Miller on the Substitution Groups whose Order is 



Pour . , . . 431 



J. Elster and H. Geitel on the alleged Scattering of Positive 



Electricity by Light 437 



T. Mizuno on the Tinfoil Grating Detector for Electric 



Waves . 445 



Prof. John Trowbridge on Carbon and Oxygen in the Sun . . 450 

 Messrs. H. Nagaoka and E. Taylor Jones on the Effects of 



Magnetic Stress in Magnetostriction 454 



Notices respecting New Books : — 



Dr. W. M. Watts's Index of Spectra, Appendix G 462 



On an Electrochemical Action of the Rontgen Rays on Silver 



Bromide, by Prof. Dr. Eranz Streinitz 462 



Triangulation by means of the Cathode Photography, by 



John Trowbridge 463 



NUMBER CCLIIL— JUNE. 



Prof .S'lasW. Holm an on Thermo-electricInterpolationEormulas 465 



Mr. W. B. Morton on the Electro-Magnetic Theory of 

 Moving Charges . . 488 



Dr. Charles H. Lees and Mr. J. D. Chorlton on a Simple 

 Apparatus for determining the Thermal Conductivities of 

 Cements and other Substances used in the Arts 495 



Mr. W. T. A. Emtage on the Relation between the Bright- 

 ness of an Object and that of its Image 504 



Mr. Rollo Appleyard on the Adjustment of the Kelvin Bridge. 506 



Mr. Julius Erith on the Effect of Wave Eorm on the Alter- 

 nate-Current Arc ' 507 



Mr. Douglas Mcintosh on the Calculation of the Conductivity 

 of Mixtures of Electrolytes having a common Ion ..... 510 



