CONTENTS OF VOL. IV. 



(FIFTH SEEIES). 



NUMBER XXII.— JULY 1877. 



Page 

 Mr.Gr. H. Darwin on Eallible Measures of Variable Quantities, 



and on the Treatment of Meteorological Observations .... 1 

 The Eev. J. M. Heath on the Production of Heat by Dyna- 

 mical Action in the Compression of Gras 14 



Prof. H. J. Smith on the Conditions of Perpendicularity in a 



Parallelepipedal System 18 



Mr. E. H. M. Bosanquet on the Theory of Sound 25 



M. Gr. Van der Mensbrugghe on the Application of Thermo- 

 dynamics to the Study of the Variations of Potential Energy 



of Liquid Surfaces 40 



Mr. S. P. Thompson on the Chromatic Aberration of the Eye 



in relation to the Perception of Distance 48 



Mr. S. P. Thompson on a Curious Effect of Absorption of 



Light 61 



Mr. S. H. Burbury on Action at a Distance in Dielectrics . . 62 

 Proceedings of the Eoyal Society : — 



Messrs. Gr. J. Stoney and H. J. Moss on Crookes's Eorce 67 

 Proceedings of the Geological Society : — 



Rear- Admiral T. A. B. Spratt on the Coal-bearing Depo- 

 sits near Erekli, the ancient Heraclea Pontica, Bithynia 74 

 The Rev. T. Gr. Bonney on the Serpentine and associated 



Rocks of the Lizard District 74 



Mr. S. Allport on certain ancient Devitrified Pitchstones 

 and Perlites from the Lower Silurian District of Shrop- 

 shire , 75 



The Rev. E. HiU and the Rev. T. G. Bonney on the 



Precarboniferous Rocks of Charnwood Eorest 76 



On the Equilibrium of Pressure in Gases, by S. Tolver Preston. 77 

 On a direct Transformation of Mechanical Work into Electri- 

 city, by E. Guignet 78 



On the Distribution of Temperature in the Conducting- wire of 



a Galvanic Current, by Heinrich Streintz 79 



On the Specific Heats of Gases, by W. M. Hicks 80 



