Geology and Mineralogy. 465 



directness of statement, and the thoroughness with which the 

 work of the many physicists who have contributed is recognized. 

 Even where only a very brief allusion is possible to some matters 

 of minor importance, they are not ignored, but the literature ref- 

 erences at the bottom of each page embrace all that has been 

 done on the subject. The great steps of progress that have been 

 made, as the Rowland grating, the methods for the investigation 

 of the infra-red spectrum by Abney, the echelon spectroscope of 

 Michelson, are treated with all necessary fullness. 



The second volume is to be devoted to Kirchhoff's law and its 

 consequences, emission spectra of different kinds and as obtained 

 under varying conditions of pressure, temperature, magnetic 

 force, etc. The third volume will include the absorption phe- 

 nomena with also fluorescence and phosphorescence; the fourth 

 volume will give all spectroscopic data available in regard to 

 each individual element, and a fifth is also planned to include the 

 sjsectroscopy of the heavenly bodies including the Sun. 



20. A Brief Course in General Physics, experimental and 

 applied ; by George A. Hoadlev, Swarthmore College. Pp. 

 463, New York, 1900 (The American Book Company). — This is a 

 clear, systematic statement of the fundamental principles and laws 

 of physics, such as is needed by the high school student ; it is 

 accompanied by good illustrations and a well-chosen series of 

 experiments. The subjects in general are well treated, although 

 at occasional points open to criticism ; thus we find in one article 

 a brief statement of surface tension and in one following, an 

 explanation of capillary attraction, but there is no suggestion 

 as to any connection between the two subjects. 



II. Geology and Mineralogy. 



1. TJ. S. Geological Survey, 20th Annual Report 1898-99. 

 Part III. Precious Metal Mining Districts. (Washington^ 

 1900, pp. 595, pis. 77.) — This volume consists of three papers, two 

 of them having appended reports by specialists. 



I, A preliminary report on the Bohemia mining region of 

 western Oregon, with notes on the Blue River mining region and 

 on the structure and age of the Cascade range by J. S. Dillee, 

 which is accompanied by a report on the fossil plants associated 

 with the lavas of the Cascade range by F. H. Knowlton (pp. 

 1-64, pis. 1-6). The brief sketch of the district shows that the 

 rocks of Calapooya Mountain, upon which the district lies, are 

 wholly of igneous origin. They consist of dacite porphyry, 

 andesites and basalts with volcanic tuffs. It is in these rocks 

 that the mines are situated which are described in the report. 

 The veins are gold-bearing. The fossil plants found in the tuffs 

 show that the latter were deposited in lakes of Miocene age. 

 The various localities from which fossil leaves have been col- 

 lected are mentioned and in his special report Knowlton describes 



