258 TJic American Geologist. ^p"^- ^'''^^■ 
While the book is devoted mainly to a description of the physical 
forces and their effects, in nature, thus being a treatise on geological 
phenomena, it also has, at the end, chapters devoted to the special physi- 
ography of the United States which describe the vi^ays in which physi- 
ographic conditions have modified animal life or directed the progress of 
settlement and the industries of the various sections. Pages 298 to 394 
are devoted to this phase of geography. Appendices are added which 
treat of the revolution of the earth, latitude and longitude, common 
minerals and rocks, the geological ages, tides, magnetism, meteorological 
instruments, weather maps, maps, laboratory equipment and field work. 
The whole constitutes an admirable illustrated epitome of dynamic geol- 
ogy and physiography and of the ways and means of intelligent ob- 
servation. It is adapted for use in High Schools. n. h. w. 
Gems and Gem Minerals; by Oliver Cummings Farrington, Chicago, 
A. W. Mumford, 1903. $3.00. 
' It is, naturally, difficult to write anything new on the subject of gems, 
particularly when one is writing for the public and perhaps hampered 
by the stipulations of a publisher. In "Gems and Gem Minerals" Dr. 
Farrington has brought together concisely and in pleasing form much 
that is instructive and essential to a good understanding of the subject 
treated. 
The book is a handsome quarto volume of some two hundred and 
odd pages, with sixteen full-page colored plates and sixty-one figures 
in the text. In it are discussed the nature and occurrence of gems, their 
meaning, physical properties, manner of cvitting, and mounting. There 
are also chapters on imitation gems and how to detect them, on super- 
stitions concerning gems, and birthstones. All these are hackneyed 
subjects, but are set forth in new dress and made available to the buyer 
of moderate means. 
The latter two-thirds of the volume, pages 66 to 223, inclusive, to be 
more explicit, are taken up with systematic descriptions of the various 
gem minerals, both in their natural and cut conditions, their mode of 
occurrence, and the localities where found. 
Few, perhaps, realize the extent to which gem mining is carried on 
in various parts of the United States. Perhaps still fewer realize how 
many minerals there are, of little value in themselves, which can be util- 
ized to advantage for decorative purposes. Quite asid-e from the faceted 
stones, which owe their beauty largely to their high refractive qualities, 
there is a large series of minerals, including Amazon-stone, varieties of 
chalcedony, and even certain types of granitic rocks, which, when cut 
cabochon and properly mounted, can be made attractive as well as unique 
ornaments. 
Aside from Tassin's Catalogue of the Gem Collection of the National 
Museum, this is the second treatise on the subject which is available 
and at all comprehensive. Kunz's "Gems and Precious Stones," the first 
edition of which appeared in 1890, is a much more elaborate treatise, 
and its colored plates, although fewer, are of higher grade ; but this is 
