Geology and Mineralogy. 17 



telephone plate when vowels and consonants were sung and 

 spoken into it. — Physical Soc, Berlin. — Nature, May 16, 1889. 



J. T. 



9. On an Electrostatic Field produced by varying Magnetic 

 Induction. — Experiments on the subject have been undertaken 

 by Dr. O. J. Lodge and Mr. A. P. Chaltock. The magnetic 

 circuit employed has a wire Gramme ring of trapezoidal section 

 wound with copper over only a part of its periphery. The indi- 

 cating apparatus was a suspended needle consisting of the op- 

 positely charged bodies carried on a small shellac arm, to which 

 a mirror or pointer was attached, and was suspended vertically 

 in the plane of the ring. Great difficulty was experienced from 

 Foucault currents when metallic films were used for the needle, 

 and the magnetic properties of other senii-conductors tried com- 

 plicated the matter. Eventually the charged bodies were made 

 of paper in the form of cylinders -J inch diameter, and § inch 

 long. Considerable trouble was caused by the electrostatic 

 action between the needle and exciting coils, and various means 

 of screening were tried and abandoned, and subsequently the 

 wire was replaced by a single spiral of copper ribbon, the outer 

 turn of which was put to earth. Observation was rendered diffi- 

 cult owing to the wandering of the zero when the needle was 

 charged. Heat also created considerable disturbance and the 

 convection currents were cut off by a series of concentric cylinders 

 of tin plate. The method of observation was to charge the two 

 insulated parts of the needle and then reverse the magnetizing 

 current in synchronism with the period of the needle, noting 

 whether the amplitude of any residual swing could be increased 

 or diminished according as the impulse assisted or opposed the 

 motion. In this way slight indications have been observed, and 

 the effects reverse when the charge of the cylinders are reversed. 

 — Physical Soc, London, May 11, 1889. j. t. 



II. Geology and Minekalogy. 



1. Fossil Fishes and Fossil Plants of the Triassic Rocks of 

 New Jersey and the Connecticut Valley, by John S. Newberry. 

 96 pp. 4to, with xxvi plates. 1888. Making vol. xiv of the 

 Monographs of the U. S. Geological Survey. — This very valuable 

 contribution to American Mesozoic geology gives the first con- 

 nected account yet published of the fossil fishes of the Triassic 

 beds, and supplements the volume by Prof. Fontaine on the Mes- 

 ozoic plants. The geological sketch, with which the Report opens, 

 contains a brief history of the views that have been presented 

 respecting the age and origin of the Triassic beds. The author, 

 in his discussion of their age, states that owing to the small num- 

 ber of plants from the Connecticut valley and New Jersey and 

 the small number of fishes from Richmond, Virginia, a satisfac- 

 tory comparison is not possible. Only one species of fish, Catop- 

 terus gracilis, is certainly known to be common to New Jersey 

 and Richmond, though Ischypterus ovatus, if identical with a 

 fragment referred to Tetragonolepis by Egerton, may be a second. 



