Page:Popular Science Monthly Volume 43.djvu/286

274 the mastodon retreated northward, and man—"the hunters"—followed.

The chapters on the Migrations, Village Life, and Defensive Works of the Moundbuilders will be read with considerable pleasure and benefit by archæological 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 illustrated.

now exerts such an influence 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 under which beginners in the art bi photography 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 simplest and best formulas for developers, intensifiers, etc., all of which have been accepted and are used by the professors of the Royal Technical High School of Berlin.

The first chapter is devoted to an examination of the different photographic apparatus in vogue among German experts, and contains also some very useful information on photographic objectives, or the combinations 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 photographers. Among the formulas for developers, the author draws attention to a new and concentrated para-amidophenol developer, which, under the name of "rodinal," has been introduced by the Aktiengesellschaft für Anilinfabrikation. This developer only needs dilution with water to be ready for use, and "is especially excellent for instantaneous photographs."

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, intensifying 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 selection 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.

regard to the value of the investigation of balneotherapy and the scientific internal administration of mineral waters, which has gone on with great benefit in Europe for centuries. Dr. Anderson, believing that California possessed valuable mineral 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 mineral waters of California, and apparently leaves nothing unsaid either as to their efficacy as health restorers or of their comparative value against well-known European mineral waters. Although the greater part of the work is devoted to an exhaustive analytical 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 different waters. The book is profusely illustrated with cuts of the mineral springs and of California's most famous health resorts.

work is elaborately got up, containing eighty-seven plates and over six hundred and fifty figures, representing a pictorial library of the insect world. In his introduction Mr. Kirby gives an unusually lucid explanation of the structures and zoological nomenclature 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 Linné, who divided all the insects known