842 



SCIENCE 



[N. S. Vol. XXVIII. No. 728 



although considerable space is devoted to a 

 presentation of the principal modifications 

 which have been proposed. While there is a 

 great temptation to break away from the estab- 

 lished classification and to introduce a scheme 

 more in harmony with the actual conditions in 

 the separate zones, the advantages of the new 

 classifications are not suiSeiently great to out- 

 weigh the simplicity and established usage of 

 the old. However attractive may be some of 

 the features of the proposed climatic zones of 

 Supan, based upon common characteristics of 

 temperature, rainfall and winds, or those of 

 Koeppen, based upon the relations of plant life 

 to certain critical values of temperature and 

 rainfall of the warmest and coldest months, or 

 of Merriam's biological zones, based upon the 

 distribution of animal life, there are serious 

 obstacles to their general acceptance; they all 

 lack a simple expression for certain definite 

 combinations of temperature, sunshine and 

 winds. The term " temperate zone " is appar- 

 ently the most objectionable, as the most ex- 

 treme climates occur within its limits, espe- 

 cially in portions of the northern hemisphere. 

 Still the word well describes the conditions of 

 the zone as a whole, especially in the southern 

 hemisphere. Even in the northern hemisphere 

 fully half the area of the zone has a water 

 surface, insuring temperate conditions. It is 

 only over the continental portions that great 

 extremes of heat and cold occur. Taking the 

 earth as a whole, the terms warm, temperate 

 and cold fairly well divide the climates of the 

 globe into three natural divisions with the 

 tropics and the polar circles as dividing lines. 

 The secondary classification of climates into 

 continental, marine and mountain is simple 

 and practical and has general acceptance. 



The author's summary of the characteristics 

 of the three principal zones is especially valu- 

 able, as the student will find in these chapters 

 a clearer and fuller synopsis of an abundant 

 literature than is available elsewhere to those 

 who read English only. 



Hygiene in the tropics is, according to the 

 author, mostly a question of sanitation, and a 

 rational mode of living, as most diseases only 

 indirectly depend upon climatic conditions. 

 Change of residence, of habits, of occupation. 



or of food, is usually of more importance than 

 change in atmospheric conditions. 



Many problems of great interest relating 

 to the life of man in the tropical, the temper- 

 ate and the polar zones receive attention in 

 chapters VIII. to X. Such topics as the labor 

 problem and climate, the government of 

 tropical possessions, dwellings in the tropics, 

 race characteristics and climate, climates and 

 crops, mental effects of weather, weather and 

 military operations, are considered, though 

 most of them are necessarily only touched 

 upon. In closing his analysis of the evidences 

 bearing upon the subject of climatic changes 

 in historic times, the author concludes that, 

 " Without denying the possibility, or even the 

 probability, of the establishment of the fact of 

 secular changes, there is as yet no sufficient 

 warrant for believing in considerable perma- 

 nent changes over large areas " — an opinion 

 shared by most students who have given the 

 subject attention. 



Mr. Ward has succeeded in presenting a 

 well-written volume, suitable for the class- 

 room, being methodical in arrangement, and 

 clear and direct in statement. The illustra- 

 tions are few in number but well selected and 

 neatly drawn. 



0. L. F. 



Johns Hopkins Univebsity, 

 November 25, 1908 



Ex-Meridian Tables. By Lieutenant Com- 

 mander Aemistead Rust, U. S. IST. New 

 York, John Wiley & Sons. 1908. 

 This work is primarily designed to put at 

 the service of the navigator convenient means 

 for reducing altitudes of celestial bodies, when 

 measured within defined limits of hour-angle 

 from the observer's meridian, to the values 

 that they would have if they had been meas- 

 ured at culmination on the observer's meri- 

 dian, and thus to provide for the application 

 of the simple method of finding the latitude 

 from a meridian altitude, which consists in 

 algebraically adding together the declination 

 and zenith distance of the observed celestial 

 body. / 



Delambre's equation, in which the whole of 

 the reduction for practical purposes is ex- 



