CONTENTS. vn 



NTLin"ber 227. 



Page 



Art. XLV. — Mathematical Theories of the Earth ; by R. S. 



Woodward 337 



XL VI. — Darkened Silver Chloride not an Oxychloride ; by 



M. Carey Lea 356 



XL VII. — Observations on some of the Trap Ridges of the 

 East Haven-Branford Region, with a map (Plate IX) ; 

 by E. O. Hovey 361 



XLVIIL— Theory of the Mica Group ; by F. W. Clarke .. 384 



XLIX. — Probable Law of Densities of the Planetary Bodies ; 



by R. Hooke .... 393 



L. — Improved Standard Clark Cell with Low Temperature 



Coefficient ; by H. S. Carhart 402 



LI. — Pseudomorphs of Native Copper after Azurite, from 



Grant County, New Mexico ; by W. S. Yeates 405 



LII. — Note on the Relation of Volume, Pressure and Tem- 

 perature in case of Liquids ; by C. Bartts 407 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics. — Colloidal Cellulose, Guignet, 408. — Watts' Dictionary 

 of Chemistry, H. F. Morley and M. M. P. Mum, 409. — Treatise on the Prin- 

 ciples of Chemistry, M. M. P. Muir : Definitions adopted by^the International 

 Congress of Electricians, Mascart, 410. — Lightning and the Eiffel Tower: 

 Transmission of power by Electricity, Deprez : Dissipation of negative electric 

 charges by sunlight and daylight, J. Ulster and H. Geitel : Photography of 

 the invisible portions of the Solar Spectrum, Ch. V. Zenger : Carbon Spectrum, 

 H. Kayser and C. Runge, 411. 



Geology. — Movement of the Upper ice of Glaciers over the Lower : Ice-Age in 

 North America, and its bearings on the Antiquity of Man, G P. Wrtght, 412. 

 — Annual Report of the Geological Survey of Arkansas for 1888, J. C. Branner, 

 413. — Jurassic Plants from Kaga, Hida, and Echizen, (Japan), Matajiro 

 Tokotama : Rivers and Valleys of Pennsylvania, W. M. Davis, 414. 



Botany and Zoology. — Die naturlichen Pflanzenfamilien, A. Engler and K. 

 Prantl : Guide pratique pour les travaux de Micrographie, Beauregard et 

 Gallippe : Contributions to the Physiology of Growth, J. Wortmann, 415. — 

 Atlas deutscher Meeresalgen, P. Schutt, P. Kuckuck, J. Reinke, 4 1 6. — Mono- 

 graph of the Horney Sponges, R. von Lendenfeld, 417 — The Bermuda 

 Islands ; a Contribution to the Physical History and Zoology of the Somers 

 Archipelago with an examination of the structure of Coral Reefs, A. Heilprin, 

 418. 



Miscellaneous Scientific Intelligence. — British Association: Scientific Papers of Asa 

 Gray, C. S. Sargent, 419. — Popular Treatise on the Winds, W. Ferrel: 

 Sixth Annual Report of the Bureau of PJthnology to the Secretary of the 

 Smithsonian Institution, J. W. Powell: Elementary Algebra, R. Graham: 

 Numbers Universalized, an Advanced Algebra, D. M. Lensenig, 420. 



Errata. 

 Page 371, line 8 from top, after railroad add cut; p. 372, line 9 from bottom, 

 for welded read joined; p. 374, line 19 from bottom, after 450 add feet; p. 375, line 

 11 from top, for E 2 read E 1. 



