IV CONTENTS OF VOL. XV. FIFTH SERIES. 



NITMBEE XCIL— FEBEUAEY. 



Prof. J. D. Everett's Elementary Investigations relating to 



Forced Vibrations ; with Applications to the Tides and to 



Controlled Pendulums 73 



Prof. E. Clausius on the Connexion between the Units of 



Magnetism and Electricity 79 



Mr. A. A. Michelson on a Method for Determining the Eate 



of Tuning-forks 84 



Mr. F. J. Smith on a New Form of Ergometer 87 



Mr. "W. W. J. Nicol on the Nature of Solution 91 



M. E. Pringsheim on the Eadiometer 101 



Prof. S. P. Thompson on the Graphic Eepresentation of the 



Law of Efficiency of an Electric Motor 124 



Prof. W. C. Bontgen on the Change in the Double Eefraction 



of Quartz produced by Electric Forces 132 



Notices respecting New Books : — 



C. Piazzi Smyth's Madeira Spectroscopic, 1881-82 144 



On an Electrodynamic Method for the Determination of the 



Ohm ; the Experimental Measurement of the Constant of 



a Long Induction-coil, by Gr. Lippmann 149 



Amount of Carbon Dioxide in the Atmosphere, by E. H. Cook 151 

 Experiments on the Direct Photography of Sound-vibrations, 



by Prof. Boltzmann . c . 151 



On Central Forces and the Conservation of Energy, by Gr. W. 



von Tunzelmann 152 



NUMBEE XCIIL— MAECH. 



Mr. S. P. Langley on the Selective Absorption of Solar 



Energy. (Plate III.) 153 



Mr. "W. Baily on the Spectra formed by Curved Diffraction- 

 gratings. (Plate II.) 183 



Prof. H. Lamb on the Basis of Statics 187 



Mr. J. T. Eiley on Capillary Phenomena. (Plate IV.) .... 191 

 Mr. A. M. Worthington on the Horizontal Motion of Floating 



Bodies under the Action of Capillary Forces. (Plate V.) . . 198 

 Mr. F. J. Smith on a High-Pressure Electric Accumulator or 



Secondary Battery 203 



Mr. E. H. M. Bosanquet on Magnetomotive Force 205 



Mr. E. H. M. Bosanquet on an Arrangement for Dividing 



Inch- and Metre-Scales 217 



Notices respecting New Books : — 



Mr. E. J. Eouth's Elementary Part of a Treatise on the 

 Dynamics of a System of Eigid Bodies ; . . . 218 



