﻿CONTENTS OF VOLUME XXXII. 



NUMBER CLXXXVII. 



Page 



Art. I. — Memorial of Edward Tuckerman ; by Asa Gray__ 1 



II. — Notes on American Earthquakes, No. 15; by C. G. 



Rockwood, Jr 7 



III. — Observations on the Tertiary and Grand Gulf of Missis- 

 sippi ; by O. Meyer _ 20 



IV. — Notes on the Volcanic Rocks of the Republic of Salva- 

 dor, Central America; by A. Hague and J. P. Iddings_ 26 



V. — The Genus Strephochetus : Distribution and Species; 



by H. M. Seely 31 



VI. — Preliminary Report on the Geology of the Cobscook 



Bay District, Maine ; by N. S. Shaler 35 



VII. — On the Well-Spherometer ; an instrument that meas- 

 ures the radius of curvature of a lens of any linear 

 aperture ; by A. M. Mayer 61 



VIII. — On some general terms applied to Metamorphism, and 



to the Porphyritic Structure of Rocks ; by J. D. Dana. 69 



SCIENTIFIC INTELLIGENCE. 



Physics and Chemistry. — On a new Absolute Electrometer, Bichat and Blondlot, 

 72. — On the Influence of Temperature on the Heat of Chemical Combination, 

 Pickering, 73. — On the Hypochlorites of Ethyl and Methyl, Sandmeyer, 74. — 

 On the Existence and Formation of Nitrates in Plants, Berthelot and Andre, 

 75. — On the earth Ya and Mosandria, Crookes: On the Spontaneous Polymer- 

 ization of volatile Hydrocarbons at ordinary temperatures, H. E. Roscoe. 76. 



Geology and Natural History. — The Cretaceous Flora of North America, New- 

 berry: Periods of enlargement and diminution in the Glaciers of the Alps, 

 Forel: Maps published by the U. S. Geological Survey, 77. — Stromatopora, 

 C. Rominger: Palasontologica Indica: Microscopic characters of some speci- 

 mens of devitrified glass, D. Herman and F. Rutley, 78. — E. 0. Ulrich's Con- 

 tributions to American Palaeontology : Class-book of Geology, A. Geikie, 79. — 

 Ancient Herbaria, Saint-Lager: The Journal of the Linnsean Society, 80. — 

 Heterogeneous Grafting: Contagious diseases of Insects. 81. — Proceedings of 

 the Davenport Academy of Natural Sciences : Annalen der k. k. Naturhis- 

 torischen Hofmuseums redigirt von Dr. Franz Bitter von Hauer, 82. 



Miscellaneous Scientific Intelligence. — American Association for the Advancement 

 of Science, 82. 



