iv CONTENTS OF \OL. XX. — FIFTH SERIES. 



Page 

 Dr. J. A. Fleming on Molecular Shadows in Incandescence 



Lamps 141 



Dr. J. D.Dana on the Origin of Coral Reefs and Islands. (Plate I.) 144 

 Dr. J. H. Gladstone on the Specific Refraction and Dispersion 



of Light by the Alums 162 



Mr. C. Tomlinson on the Bleaching of Iodide of Starch by 



means of Heat 168 



Capt. W. de W. Abney on the Production of Monochromatic 



Light, or a Mixture of Colours, on the Screen 172 



Mr. W. Sutherland on the Mechanical Integration of the 



Product of two Functions 175 



Mr. S. Bidwell on the Sensitiveness of Selenium to Light, and 



the Development of a similar Property in Sulphur 178 



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

 under the names Law of Avogadro and Law of Dulong and 



Petit 191 



Notices respecting New Books : — 



Lieut. Lefroy's Diary of a Magnetic Survey of a Portion 

 of the Dominion of Canada, chiefly in the North-western 



Territories, executed in the years 1842-44 204 



Proceedings of the Geological Society : — 



Prof. T. G. Bonney on the so-called Diorite of Little 

 Knott (Cumberland), with further Remarks on the 



Occurrence of Picrites in Wales 205 



Mr. AV. H. Penning's Sketches of South-African Geology. 

 — No. 2. A Sketch of the Gold-Pields of the Transvaal, 



South Africa 206 



Dr. Charles Ricketts on some Erratics in the Boulder-clay 

 of Cheshire, &c, and the Conditions of Climate they 



denote 207 



Messrs. J. E. Marr and T. Roberts on the Lower Palaeozoic 



Rocks of the Neighbourhood of Haverfordwest 208 



Mr. AV. S. Gresley on certain Eossiliferous Nodules and 

 Fragments of Haematite (sometimes Magnetite) from 

 the (so-called) Permian Breccias of Leicestershire and 



South Derbyshire 209 



Prof. J. AV. Judd and Mr. C. Homersham's Supplementary 



Notes on the Deep Boring at Richmond, Surrey .... 210 

 Mr. AV. AV. AVatts on the Igneous and Associated Rocks 

 of the Breidden Hills in East Montgomeryshire and 



West Shropshire 211 



Captain F. AV. Hutton's Correlations of the Curiosity- 

 Shop Beds, Canterbury, New Zealand 212 



On Hygrometry, by M. Jamin 213 



On the Deformation of the Luminous Wave -surface in the 



Magnetic Eield, by E. von Fleischl 216 



On a new Method for Determining the Mechanical Equivalent 



of Heat, by A. G. Webster 217 



New Form of Hygrometer, by M. Bourbouze 220 



