CONTENTS OF N° 2^0.— Fourth Series, 



I. What determines Molecular Motion ? — the Fundamental Problem 



of Nature. By James Croll, of the Geological Survey of Scotland, page 1 



II. On a new Lantern-Galvanometer. By Alfred M. Mayer, Ph.D., 

 Professor of Physics in the Stevens Institute of Technology, Hoboken, 

 N. J., U.S. America 25 



III. On the steady Flow of a Liquid. By the late Henry Moseley, 

 M.A., D.C.L., Canon of Bristol, F.R.S., Corresponding Member of 

 the Institute of France, &c. Edited by Walter R. Browne, M.A., 

 Fellow of Trinity College, Cambridge. (With a Plate.) 30 



IV. On Variations of Pitch in Beats. By Sedley Taylor, Esq., 

 late Fellow of Trinity College, Cambridge 56 



Y. On Mr. Moon's Views on Gaseous Pressure. By the Hon. J. 

 W. Strutt, M.A., late Fellow of Trinity College, Cambridge 64 



VI. On a Bicyclic Chuck. By A. Cayley, F.R.S Qb 



VII. Notices respecting New Books : — An Introductory Algebra, 

 containing the chief rules in the first part of Colenso's Elements of 

 Algebra simpKfied ; with additional illustrations &c. By the Right 

 Rev . J. W. CoLExso, D.D., Lord Bishop of Natal, and the Rev. J. 

 Hunter, M.A., formerly Vice-Principal of the National Society's 

 Training College, Battersea. — A Treatise on Attractions, Laplace's 

 Functions, and the Figure of the Earth. By John H. Pratt, M.A., 

 F.R.S., Archdeacon of Calcutta 67-68 



VIII. Proceedings of Learned Societies : — 



Royal Institution : — ^li. W. Spottiswoode on Optical Pheno- 

 mena produced by Crystals submitted to Circularly Polarized 

 Light 69 



Royal Society : — Dr. J. H. Gladstone and Mr. A. Tribe on 

 the Decomposition of Water by Zinc in conjunction with a more 

 Negative Metal 73 



IX. Intelhgence and Miscellaneous Articles : — 



On the Influence of Pressure on the Lines of the Spectrum, by 



M. L. Cailletet 76 



Further Researches on the Reflection of Heat, by M, P. Desains. 77 

 On Electrical Pyrometry, by Lieut. Abney, R.E., F.R.A.S., F.C.S., 

 Assistant Instructor in Telegraphy, S.M.E,, Chatham 80 



It is requested that all Communications for this Work may be addressed, 

 post-paid, to the Care of Messrs. TaylcH- and Francis, Printing Office. Red 

 Lion Court, Fleet Street. London. 



