IV CONTENTS OF VOL. XXXII. FOURTH SERIES. 



Page 

 Archdeacon Pratt : to find what changes may be made in the 

 arrangement of the mass of a body, without altering its out- 

 ward form, so as not to affect the attraction of the whole 



on an external point 132 



Mr.D.Forbes's Researches on the Mineralogy of South America. 135 

 Proceedings of the Royal Society :-—• 



Mr. F. A. Abel on the Manufacture and Composition of 



Gun-cotton. , , . . 145 



Mr. H. Wilde's Experimental Researches in Magnetism 



and Electricity 148 



Proceedings of the Geological Society : — 



The Rev. F. W. Holland on the Geology of Mount Sinai. 152 

 Mr. H.Woodward on a new Genus of Phyllopodous Crusta- 

 cea from the Moffat Shales, Dumfriesshire, on the oldest 

 known British Crab from Wilts, and on the species of the 

 genus Eryon, Desm., from the Lias and Oolite of Eng- 

 land and Bavaria 153 



Mr. J. Plant on the Discovery of Primordial Fossils in the 



neighbourhood of Tyddynglwadis Silver Lead-mine. . . . 153 

 Prof. R. Harkness on the Metamorphic and Fossiliferous 



Rocks of the Co. Galway 154 



Mr. J. Geikie on the Metamorphic Lower Silurian Rocks 



of Carrick, Ayrshire 154 



Prof. W. C. Williamson on a Cheirotherian Footprint from 



the base of the Keuper Sandstone of Daresbury, Cheshire 155 

 Mr. J. W. Pike on some remarkable " Heaves " or Throws 



in Penhalls Mine 155 



On the comparative Visibility of Arago's, Babinet's, and Brew- 

 ster's Neutral Points, by Mr. Chase 156 



On Ostrogradsky's Hydrostatical Paradox, by Chief Justice 



Cockle, F.R.S 157 



Contributions towards the more accurate knowledge of the Phe- 

 nomena of Fluorescence, by Dr. Victor Pierre of Prague . . 159 



NUMBER CCXV.— SEPTEMBER. 



Mr. F. Jenkin's Reply to Dr. Werner Siemens' s Paper " On the 



Question of the Unit of Electrical Resistance " 161 



Prof. R. Bunsen on the Phenomena observed in the Absorption- 

 spectrum of Didymium. (With Two Plates.) 177 



Prof. Frankland on the Origin of Muscular Power 182 



Mr. I. Todhunter on a Problem in the Calculus of Variations. 199 



Prof. W. A. Norton on Molecular Physics. 205 



Mr. A. Claudet on the Optics of Photography. — On a new 

 Process for Equalizing the Definition of all the Planes of a 



Solid Figure represented in a Photographic Picture 212 



The Rev. S. Haughton's Notes on Mineralogy . , 220 



