SCIENTIFIC LITERATURE. 



563 



by the use of simple language and many 

 photo-engravings of well- selected specimens 

 he makes their nature remarkably clear. In 

 the dynamical division the processes of 

 weathering, erosion, deposition, stratifica- 

 tion, metamorphism, and the formation of 

 mountains, volcanoes, etc., are made clear by 

 the same means. The stratigraphical divi- 

 sion probably contains as much material as 

 the pupil is likely to assimilate. It opens 

 with an explanatory chapter on the uses of 

 fossils, then the kind of life that prevailed 

 in each geologic age is described with the 

 aid of figures of fossils and ideal landscapes 

 of the several ages, and the account closes 

 with an outline of the changing geography 

 of the United States from Archasan to Ceno- 

 zoic time. Throughout the work the author 

 is careful to distinguish important doctrines 

 that are proved from those that remain hy- 

 pothetical. The volume is printed in large, 

 clear type, and contains two hundred and 

 sixty-eight figures and twenty-five plates, in- 

 cluding a colored geological map of the 

 United States. 



His various investigations and writings, 

 extending over a term of years, have well 

 equipped Prof. Israel C. Russell with ma- 

 terial for making a book on the North 

 American glaciers.* In the volume which 

 he has recently put forth he not only enu- 

 merates and describes the glaciers of this 

 continent that have been explored, but he 

 also explains the theory and depicts the behav- 

 ior of these solid rivers, so that the reader 

 untrained in science may follow him. The 

 glaciers of the Alps, being in a region that 

 is surrounded on all sides by thickly popu- 

 lated countries, have been the most studied. 

 But Prof. Russell points out that " North 

 America offers more favorable conditions for 

 the study of existing glaciers and of the rec- 

 ords of ancient ice sheets than any other 

 continent. Of each of the three leading 

 types of glaciers thus far recognized name- 

 ly, the Alpine, Piedmont, and continental 

 North America furnishes magnificent exam- 

 ples." After describing the glaciers of each 

 locality from the Sierra Nevada Mountains 

 to Greenland, our author discusses the cli- 



* Glaciers of North America. By Israel C. 

 Russell. Boston : Ginn & Co. Pp. 210, 8vo. 

 Price, $1.90. 



matic changes indicated by the glaciers of 

 North America and the evidence that the 

 great ice sheets are retreating. The how 

 and why of glacier movement, and the life 

 history of a glacier, form the subjects of the 

 two closing chapters. The volume is illus- 

 trated with twenty-two plates and ten smaller 

 figures. 



"There is perhaps little that need be 

 said prefatory to a work of this charac- 

 ter," say the authors of a volume of prob- 

 lems, and for the same reason a description 

 of the work can not be long.* The authors 

 have prepared it in the beUef that any text 

 in physics needs to be supplemented by 

 problem work in considerable variety. An 

 introduction contains the tables of physical 

 constants required in working the problems, 

 while tables of logarithms, sines, etc., and a 

 fist of answers appear at the end of the vol- 

 ume. The use of directed quantities, graphic 

 methods, averages, and approximations is 

 briefly set forth in several preliminary chap- 

 ters. The problems are divided among the 

 subjects of mechanics, solids, the behavior 

 of liquids and gases, beat, electricity, mag- 

 netism, sound, and light. A few problems 

 have been inserted which can not be satis- 

 factorily worked by other than calculus 

 methods, while here and there graphic 

 methods have been suggested that may be 

 profitably extended by the student. Occa- 

 sional questions not requiring numerical an- 

 swers have been asked. 



The fourth volume of the American His- 

 tory Series deals with a period of growth. 

 Between 1817 and 1858 the territory of the 

 United States was increased by the acquisi- 

 tion of Florida, Texas, and Oregon.f The 

 population of the older States, pushing 

 toward the west and southwest, made set- 

 tlements and organized communities in the 

 hitherto unorganized territories. In this 

 task they were largely re-enforced by immi- 

 grants from Europe. It was a period also 

 of the growth of pent-up forces, which later 

 produced the outbreak of the civil war. 



* Problems and Questions in Physics. By 

 Charles P. Matthews and John Shearer. New 

 York : The Macmillan Company. Pp. 247, 8vo. 

 Price, $1.60. 



t The Middle Period, 1817-1858. By John W. 

 Burgess. New York : Charles Scribner'e Sons. 

 Pp. 544, 12mo. Price, $1.75. 



