CONTENTS OF VOL. XX. 



(FIFTH SEEIES). 



NUMBER CXXIL— JULY 1885. 



Page 

 Dr. L. B. Fletcher on a Determination of the B.A. Unit in 



Terms of the Mechanical Equivalent of Heat 1 



Mr. J. Edmondson on Calculating-Machines 15 



J. A. Groshans on a New Law, analogous to those known 

 under the names Law of Avogadro and Law of Dulong and 



Petit 19 



Mr. H. P. Newall on Colliding Water-jets 21 



MM. Elster and Geitel's Observations on the Electrical Pro- 

 cesses in Thunder-clouds 34 



Assistant-Prof. J* W. Clark on certain Cases of Electrolytic 



Decomposition 37 



Assistant-Prof. J. W. Clark on the Determination of the Heat- 

 Capacity of a Thermometer 48 



Mr. A.M. Worthington on the Error involved in Professor 

 Quincke's Method of Calculating Surface-Tensions from the 



Dimensions of Plat Drops and Bubbles 51 



Prof. Oliver Lodge on the Stream-Lines of Moving Vortex- 

 rings. (Plates IT., III., IV.) 67 



Notices respecting New Books : — 



Dr. E. Hoppe's Geschichte der Elektrizitat 70 



Proceedings of the Geological Society : — 



Mr. T. Mellard Eeade on the Evidence of the Action of 



Land-Ice at Great Crosby, Lancashire 73 



Mr. D. C. Davies on the North-Wales and Shrewsbury 



Coal-field \ 73 



On the Depth to which Daylight penetrates in Sea-water, by 



MM. H. Eol and Ed. Sarasin 74 



On the Electrical Conductivity of Solid Mercury and of Pure 



Metals at Low Temperatures, by MM. Cailletet and Bouty . 77 

 Optical Method for the Absolute Measurement of Small 

 Lengths, by M. Mace de Lepinay 79 



NTTMBEK CXXIIL— AUGUST. 



Prof. L. Henry on the Polymerization of the Metallic Oxides. 81 

 Mr. J. Buchanan on the Thermoelectric Position of Carbon. 



(Plate VIII.) , 117 



Dr. J. A. Fleming on the Use of Daniell's Cell as a Standard 



of Electromotive Force. (Plate V.) , 126 



