CONTENTS. 



Page 



Art. XV. — Magnetic Field in the Jefferson Physical Lab- 

 oratory ; by R. W. Willson 87 



XVI. — Cretaceous Plants from Martha's Vineyard ; by D. 



White. (With Plate II) 93 



XVII.— Review of Dr. R. W. Ells's Second Report on the 

 Geology of a Portion of the Province of Quebec ; by 

 C. D. Walcott -. -. 101 



XVIII. — Measurement by Light-waves ; by A. A. Michelson. 



(With Plate III) 115 



XIX. — Lansfordite, Nesquehonite, a new Mineral, and Pseuclo- 

 morphs of Nesquehonite after Lansfordite ; by F. A. 

 Genth and S. L. Penfield. (With Plate IV) _ 121 



XX.— Weber's Law of Thermal Radiation ; by W. Fereel. 137 



XXI. — Tracks of organic origin in rocks of the Auimikie 



group ; by A. R. C. Selwyn __ 145 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics. — Periodic Law, Mendeleeff, 147. — Sonorous Sand in 

 the Peninsula of Sinai, H. C. Bolton, 151. — Electromagnetic effect of Convec- 

 tion, F. Himstedt: Mechanical equivalent of Light, 0. Tumlirz, 153. — 

 The Bolometer, R. v. Helmholtz: Cavendish Experiment, C. V. Boys: Report 

 on the Magnetic Results of the Voyage of H. M. S. Challenger, 154. 



Geology and Mineralogy. — Report of the State Geologist of New York for 1 888, 

 155. — A new Reptile from Saxony, G. Baur, 156. — American Geological Society, 

 ] 58.— New fossils from the Lower Cambrian. C. D. Walcott: A Lingula with 

 cast of its peduncle, C. D. Walcott: Cambrian fossils in the Salt Range, India, 

 A. Warth: Wulfenite from Sing Sing, N. Y.: Rutile-Edisonite, 159.— Native 

 Gold in Calcite, J. S. Diller : Brief Notices of some recently described Miner- 

 als, 160.— Native Arsenic from Colorado, C. Hersey: Catalogue of Minerals 

 found in New Jersey, F. A. Canfield, 161. 



Botany and Zoology. — Hybrids, G. de Saporta, 161. — Cause of the ascent of sap, 

 J. Boehm: Memoirs of the Torrey Botanical Club, L. H. Bailey and I. C. Mar- 

 tindale : Nitrification of Ammonia, T. Schlceshstg : Part which Ammonia plays 

 in the nutrition of higher plants, A. Muntz, 162. — Fixation of Nitrogen by 

 Leguminous plants, E. Breal : Economic Mollusca of New Brunswick, W. F. 

 Ganong: Bibliotheca Zoologica, 0. Taschenberc, 1 63. 



Miscellaneous Scientific Intelligence. — American Metrological Society, 163. — Royal 

 Society of N. S. Wales : Reports of Examinations of Waters and Water Supply 

 during 1886-89, E. W. Hilgard, 165. — Arthrolycosa antiqua of Harger, 166. 



Obituary. — Charles Albert Ashburner, 166. 



BECKER BROTHERS, 



No. 6 Murray Street, New York, 



Manufacturers of Balances and Weights of Precision for Chem- 

 ists, Assayers, Jewelers, Druggists, and in general for every use 

 where accuracy is required. 



