VI CONTENTS OF \OL. XXI. FIFTH SERIES. 



Page 

 Mr. E. Witehell on the Basement-beds of the Inferior 



Oolite of Gloucestershire 363 



Messrs. P. F. Kendall and E. G. Bell on the Pliocene 



Beds of St. Erth 363 



Mr. Gr. A. J. Cole on the Alteration of coarsely Spheru- 



litic Rocks 364 



Mr. H. B. Woodward on a "Well-sinking made by the 



Great "Western Railway Company at Swindon 365 



On the Resistance in the Voltaic Arc, by E. Edlund 366 



On the Deviation of Oxygen from Boyle and Mariotte's Law 

 under Low Pressures, by Christian Bohr, of Copenhagen . . 368 



NUMBER CXXXIL— MAY. 



Lord Rayleigh on the Reaction upon the Driving-point of a 

 System executing Forced Harmonic Oscillations of various 

 Periods, with Applications to Electricity 369 



Lord Rayleigh on the Self-induction aud Resistance of Straight 

 Conductors 381 



Prof. S. P. Langley's Observations on Invisible Heat-Spectra 

 and the Recognition of hitherto Unmeasured "Wave-lengths, 

 made at the Allegheny Observatory. (Plate IV.) 394 



Mr. A. P. Laurie on Measurements of the Electromotive 

 Force of a Constant Voltaic Cell with moving Plates .... 409 



Mr. W. Baily on a Map of the "World on Flamsteed's Pro- 

 jection. (Plate V.) 415 



Mr. C. Tomlinson's Note on Supersaturated Saline Solutions. 417 



Prof. J. H. Poynting on Discharge of Electricity in an Im- 

 perfect Insulator 419 



Dr. T. E. Thorpe and Mr. A. "W. Riicker on a " Relation 

 between the Critical Temperatures of Bodies and their 

 Thermal Expansions as Liquids " 431 



Prof. Balfour Stewart on the Cause of the Solar-Diurnal 

 Variations of Terrestrial Magnetism 435 



Notices respecting New Books : — 



Dr. Helmholtz's Sensations of Tone as a Physiological 

 Basis for the Theory of Music 445 



Proceedings of the Geological Society : — 



Dr. "W. T. Blanford on additional Evidence of the Oc- 

 currence of Glacial Conditions in the Palaeozoic Era, 

 and on the Geological Age of the Beds containing 

 plants of Mesozoic type in India and Australia 448 



Magnetic Investigations, by G. "Wiedemann 449 



A Lecture Experiment on the Diffusion of Gases, by A. 

 "Winkelmann 451 



On Vapour and Mist, by Robert von Helmholtz 451 



On the Weight and the Cause of the Layer of Water on Glass 

 and other Bodies, by E. "Warburg and T. Ihmori 452 



