518 



SCIENCE 



[N. S. Vol. LIII. No. 1379 



the Bureau of Soils, United States Depart- 

 ment of Agriculture. The Macmillan Com- 

 pany, New York. 1920. Pp. xviii -f 399. 

 Illustrations: 56 plates, general soil map of 

 the Southern States (frontispiece), and 

 four additional maps. 



This book departs from the usual trend of 

 books on soils in that instead of dealing with 

 the properties and nature of soils in general 

 the author describes the origin, geographic 

 distribution, physical characteristics, agricul- 

 tural adaptations and management of all the 

 important soils occuring in the area under 

 discussion. The states included in the work 

 are those lying south of the north boundaries 

 of Delaware, Maryland and West Virginia, 

 soutli of the Ohio Eiver, and south and east 

 of and including Missouri, Kansas and Texas. 

 In the introduction the author explains the 

 division of the country under consideration 

 into soil provinces and subordinate soil 

 regions, and describes the United States 

 Bureau of Soils system of classification and 

 nomenclature of soil series and types. The 

 introduction further takes up the geograph- 

 ical distribution and in general the adapta- 

 tion to different soils of the various crops 

 grown in the South; and the influence of 

 climate on soils and crops. 



The general geography, topography, geology 

 and agriculture of each soil province and its 

 subordinate soil regions are discussed, fol- 

 lowed by detailed descriptions of the indi- 

 vidual soils. These descriptions include the 

 location, physical and frequently chemical 

 characteristics, topography, drainage and crop 

 adaptation of each soD, and methods of soil 

 management and fertilization which actual 

 farm practise and experimentation have 

 proven to be most effective. 



Four appendixes include discussions of the 

 meanings of terms used in soil classification, 

 chemical analyses of representative southern 

 soils, a bibliography of important publications 

 on soils and related subjects, and statistics 

 bearing on some of the important farm prod- 

 ucts of the southern states. 



The book is valuable not only to students 

 and agricultural investigators but also to 



farmers and especially to those contemplating 

 settling in the south. Wm. B. Cobb 



Depastment op Agsonomt, 

 Louisiana State Univeesity 



SPECIAL ARTICLES 



AN AGE-COMPUTING DEVICE 



1. In a recent issue of Science (1920, No. 

 1336, pp. 134-135), Dr. Slonaker describes a 

 device for the simultaneous determination of 

 the ages of two individuals at different times 

 in their lives, involving the use of a calendar 

 in which the days are numbered consecutively 

 throughout the year. The present device ob- 

 viates the need of the cajendar and the need 

 for resetting for dates in different years. As 

 used with reference to human beings, two 

 accessory scales aid in determining in years 

 the age of an individual at different episodes 

 in his life, when his present age and the years 

 in which the episodes occurred are knovm, 

 and vice versa. 



Age-Computing Circular Slide Rule 



2. A small disk 2 inches in diameter, a 

 larger disk 3J inches in diameter, and a 4i- 

 inch square are cut from a sheet of opaque 

 white celluloid and, with thin washers inter- 

 vening, are pivoted at their centers on an 

 eyelet. The square is cut further to present 

 a semi-circular border from one end of the 

 transverse diameter to the other. An adjust- 



