CONTENTS OF VOL. XLVII. FOURTH SERIES. V 



Page 

 Mr. T. Davidson on some Brachiopoda collected by Mr. 

 Judd from the Jurassic Deposits of the East Coast of 



Scotland 230 



Prof. D. T. Ansted on Solfataras and deposits of Sulphur 



at Kalamaki 230 



Mr. J. Lucas on the Origin of Clay-Ironstone 231 



Dr. Dawson on Leptopliloeum rhombicum and Lepidoden- 



dron gaspianum 231 



Capt. F. W. Hutton on the younger formations of New 



Zealand 232 



Mr. W. Carruthers on the Tree Ferns of the Coal-mea- 

 sures 233 



Mr. A. H. Schindler on the Geology of Kazirun 233 



The Rev. T. G. Bonney on the Lakes of the Xorth- eastern 



Alps 234 



Signor B. Gastaldi on the Effects of Glacier-erosion in 



Alpine Valleys 235 



On the Limits of the effective Power of Microscopes, by Pro- 

 fessor Helmholtz * 236 



Experimental Researches on Newton's Coloured Rings, by P. 



Desains 236 



On extraordinary developments of Light in the grinding of 

 hard Stones, by Dr. Jacob Noggerath 237 



NUMBER CCCXIL— APRIL. 



Prof. J. P. Cooke on the Yermiculites ; their Crystallographic 

 and Chemical Relations to the Micas ; together with a dis- 

 cussion of the Cause of the Variation of the Optical Angle in 



these Minerals (With a Plate.) 241 



M. H.Vogel on the Sensibility to Light of Bromide of Silver 



with respect to the so-called Chemically Inert Colours .... 273 

 Prof. Chains on the Effects produced by Fog and Vapour in 



the Atmosphere on the Litensity of Sound 277 



M. Gr. Lippmann on the Connexion between CapUlary and 



Electrical Phenomena. (With a Plate.) 281 



Mr. R. Moon on the Measure of Work in the Theory of Energy. 291 

 M. F. Kohlrausch on the Determination of the Absolute Value 



of the Siemens Mercury Unit of Electrical Resistance .... 294 

 Proceedings of the Royal Society : — 



Sir B. C. Brodie on the Electric Decomposition of Car- 

 bonic-Acid Gas 309 



Messrs. Lockyer and Roberts on the Quantitative Ana- 

 lysis of certain Alloys by means of the Spectroscope . . 311 

 Mr. J. A. Broun on the Period of Hemispherical Excess 

 of Sun-spots, and the 26-day Period of Terrestrial 

 Magnetism 311 



