**-* CONTENTS of N° 263.— Fourth Series. 



LVIII. A Theory of Nebulseand Comets. By A. S. Davis, B.A., 

 Mathematical Master, Leeds Grammar School . . page 401 



LIX. Thermo-chemical Researches. By M. Julius Thomsen .. 410 



LX. On Thermodynamics. By the Rev. J. M. Heath 421 



LXI. On an Optical Illusion. By J. L. Tupper 423 



LXII. On an Electromagnetic Experiment. By ( the Hon. J. W. 

 Strutt, Fellow of Trinity College, Cambridge 428 



LXIII. Supplement to a Mathematical Theory of Oceanic Tides. 

 By the Rev. Professor Challis, M.A., F.R.S., F.R.A.S 435 



LXIV. On the Connexion between the Electrical Insulating-power 

 and Chemical Composition of various kinds of Glass. By F. L. Ekman, 

 Junior Professor at the Royal Technological Institute in Stockholm. 437 



LXV. On the Change in the Radiation of Heat by Roughness of 

 the Surface. By the late Prof. G. Magnus 445 



LXVI. Proceedings of Learned Societies : — 



Royal Society : — Mr. H. C. Sorby on some remarkable Spec- 

 tra of Compounds of Zirconia and the Oxides of Uranium ; 

 Dr. W. J. M. Rankine on the Mathematical Theory of 

 Stream-lines, especially those with four Foci and upwards. 450-462 



Geological Society : — Mr. C. Moore on Australian Mesozoic 

 Geology and Palaeontology, and on a Plant- and Insect-bed on 

 the Rocky River, New South Wales 462-463 



LXVII. Intelligence and Miscellaneous Articles: — 



On the Inexpediency of Erroneous Hypotheses, by Charles 

 Brooke 464 



Results of a Research on the Absorption-spectrum of Iodine- 

 vapour, by Robert Thalen 465 



On a simple Method of dispensing with observations of Tempera- 

 ture and Pressure in Gas-analyses, by Wolcott Gibbs, M.D. . . 465 



Physical Notices, by J. Miiller 467 



Index 468 



With Title-page, Contents, &c. 



41 xt 



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

 Lion Court, Fleet Street, London. 



