IV CONTENTS. 



Number 188. 



Page 



Art. IX. — Experimental Investigation on the Reflection of 

 Light at Certain Metal-Liquid Surfaces ; by L. P. 

 Wheeler 85 



X. — Recent Gravity Work in the United States ; by W. 



Bowie 101 



XI. — Crystal Forms of Pyromorphite ; by O.Bowles 114 



XII. — Some New Mechanical Quadratures ; by 6. F. Becker 117 



XIII. — Comparative Age of the Recent Crinoid Faunas ; 



by A. H. Clark... 127 



XIV. — Study of Some American Fossil Cycads. Part V. 



Further Notes on Seed Structures ; by G. R. Wieland 133 



XV. — New Locality of Pyrrhotite Crystals and their Pseu- 



domorphs ; by C. H. Smyth, Jr 156 



XVI. — Ferritungstite, a New Mineral ; by W. T. Schaller 161 



XVII.— Method of Removing Tests from Fossils ; by S. S. 



BUCKMAN 163 



XVIII. — Decomposition of the Cerium Earth Double Sul- 

 phates with the Alkali Sulphates by Fusion with Char- 

 coal ; by P. E. Browning and P. L. Blumenthal 164 



SCIENTIFIC INTELLIGENCE. 



Geology and Mineralogy — La Granodiorita de Concepcion del Oro en el 

 Estado de Zacatecas, y sus Formaciones de Contacto, A. Bergeat : Four- 

 teenth Annual Eeport of the Geological Commission of the Cape of Good 

 Hope for 1909, 166. — Norwegian Geological Survey : State of Tennessee, 

 State Geological Survey : Handbuch der Mineralogie, C. Hintze : Cata- 

 logue of the Minerals of Tasmania, W. F. Pettekd : Minerals of Guana- 

 juato, Mexico, E. Wittich, 167. — Minerals from the Belgian Congo, H. 

 Buttgenbach : Die Anwendung der stereographischen Projektion bei 

 kristallographischen Untersuchungen, H. E. Boeke, 168. 



Miscellaneous Scientific Intelligence — Second Course in Algebra, H. E. 

 Hawkes, W. A. Luby and F. C. Touton : Les Progres et L'Evolution de 

 L'Astronomie, J. Mascart, 168. 



