CONTENTS OF VOL. XXXIII. FIFTH SERIES. 



NUMBER CCII.— MARCH. 



Prof. T. G. Bonney's Petrological Notes on the Euphotide or 

 Saussurite-smaragdite Gabbro of the Saasthal 237 



Mr. J. McCowan on the Theory of Long Waves and its 

 Application to the Tidal Phenomena of Rivers and Estuaries. 250 



Mr. J. Walker on the Intensity at the Focal Point of a Tele- 

 scope, when the Object-glass is covered by a Diaphragm 

 pierced with Circular Apertures 266 



Prof. J. Perry on Struts and Tie-Rods with Lateral Loads . . 269 



Mr. S. U. Pickering on the Hypothetical Tetrachloride of 

 Manganese 284 



Sir W. Thomson on the Kinetic Theory of the Dissipation of 

 Energy 291 



Messrs. W. Lucas and T. A. Garrett on a Detector for Spark 

 in Hertz's Resonator 299 



Prof. L. Natanson's Dynamical Illustration of the Isothermal 

 Formula , . . . . 301 



Mr. W. Hibbert on a Permanent Magnetic Field 307 



Notices respecting New Books : — 



: ~Mr. J. F. Blake's Annals of British Geology, 1890 .... 314 



On the Refraction of Sound, and its Velocity in Porous Sub- 

 stances permeable to Sound, by N. Hesehus 316 



NUMBER CCIIL— APRIL. 



Dr. T. Ewan on the Absorption-Spectra of some Copper Salts 



in Aqueous Solution 317 



Dr. G. Gore on Chemical Equilibrium in Mixed Electrolytes . . 342 

 Prof. A. Anderson on the Resistance and Self-induction of 



Branched Circuits 352 



Lord Rayleigh on Maxwell's Investigation respecting Boltz- 



mann's Theorem 356 



Mr. C. Tomlinson on an Experiment Illustrative of the 



Formation of Rocking Stones 359 



Lord Rayleigh's Experiments upon Surface-Films 363 



Mr. John Trowbridge on Wave Propagation of Magnetism . . 374 

 Messrs. E. L. Nichols and B. W. Snow on the Selective 



Absorption of Light by Optical Glass and Calc-spar 379 



Notices respecting New Books : — 



F. Karrer's Guide through the Collection of Building- 

 materials in the Imperial Natural-history Museum at 



Vienna 382 



Mr. A. M. Worthington's Dynamics of Rotation 3S3 



