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THE POPULAR SCIENCE MONTHLY 



tion the mastodon retreated northward, and 

 man — "the hunters" — followed. 



The chapters on the Migrations, Village 

 Life, and Defensive Works of the Mound- 

 builders will be read with considerable pleas- 

 ure and benefit by archaeological students. 

 Dr. Peet has given the results of his research 

 in a style that will be acceptable even to 

 non-students. The work is profusely illus- 

 trated. 



Practical Pocket-book of Photography. 

 By Dr. E. Vogel. Translated by E. C. 

 Conrad, F. C. S. London: Swan, Son- 

 nenschein & Co. New York : Macmillan 

 & Co. 1893. Pp. 202. Price, $1. 



Photography now exerts such an influ- 

 ence upon current literature and general 

 events that a handbook such as that which 

 Dr. Vogel has produced is not alone timely, 

 but useful. One of the great difficulties un- 

 der which beginners in the art of photogra- 

 phy labor is the fact that the formulas and 

 instructions in most guides are too many, too 

 complex, and too incomplete. In this little 

 volume the author has selected only the sim- 

 plest and best formulas for developers, in- 

 tensifiers, etc., all of which have been ac- 

 cepted and are used by the professors of the 

 Royal Technical High School of Berlin. 



The first chapter is devoted to an exami- 

 nation of the different photographic appara- 

 tus in vogue among German experts, and 

 contains also some very useful information 

 on photographic objectives, or the combina- 

 tions of lenses that are capable of giving an 

 optical image. Instantaneous photography 

 is also treated in this chapter, and some 

 simple rules by which exposures should 

 be determined will be read with profit by 

 both amateur and professional photogra- 

 phers. Among the formulas for developers, 

 the author draws attention to a new and con- 

 centrated para-amidophenol developer, which, 

 under the name of " rodinal," has been intro- 

 duced by the Aktiengesellschaft f iir Anilin- 

 f abrikation. This developer only needs dilu- 

 tion with water to be ready for use, and " is 

 especially excellent for instantaneous photo- 

 graphs." 



In the fifth part of Chapter IV, Dr. Vogel 

 gives some very simple instructions for the 

 recovery of silver from residues, which will 

 be useful for those who use developers, in- 



tensifying baths, etc., in large quantities. 

 The fifth chapter is devoted to the positive 

 processes, which are examined in brief detail. 

 The book is illustrated fully, and the se- 

 lection of cuts and diagrams is admirably 

 suited to the subject matter. The translator 

 has added some important foot-notes to the 

 general text, which was evidently written for 

 the use of German students by Dr. Vogel. 



Mineral Springs and Health Resorts of 

 California. By Winslow Anderson, 

 M. D. San Francisco: The Bancroft 

 Company. 1892. Pp. 384. 



Having regard to the value of the inves- 

 tigation of balneotherapy and the scientific 

 interna] administration of mineral waters, 

 which has gone on with great benefit in 

 Europe for centuries, Dr. Anderson, believ- 

 ing that California possessed valuable min- 

 eral springs, spent several years examining 

 and comparing the waters of that State, 

 and gives the result of his labors in this 

 work. It is a perfect revelation of the min- 

 eral waters of California, and apparently 

 leaves nothing unsaid either as to their effi- 

 cacy as health restorers or of their compara- 

 tive value against well-known European min- 

 eral waters. Although the greater part of 

 the work is devoted to an exhaustive ana- 

 lytical examination of the waters, a fund of 

 useful information is added on the ancient 

 uses of mineral springs, their classification, 

 and the theory of their origin, with the 

 therapeutics or medicinal uses of the differ- 

 ent waters. The book is profusely illustrated 

 with cuts of the mineral springs and of Cali- 

 fornia's most famous health resorts. 



Elementary Text-book of Entomology. By 

 W. F. Kirby, T.L. S. Second edition. 

 London : Swan, Sonnenschein & Co. New 

 York : Macmillan & Co. 1892. Pp.281. 

 Price, $3. 



Thts work is elaborately got up, contain- 

 ing eighty-seven plates and over six hundred 

 and fifty figures, representing, a pictorial li- 

 brary of the insect world. In his introduction 

 Mr. Kirby gives an unusually lucid explana- 

 tion of the structures and zoological nomen- 

 clature of the insect tribe, which he divides 

 into four classes of animals having bodies 

 composed of a number of joints or segments. 

 He pays reverent tribute to the researches 

 of Linne, who divided all the insects known 



