542 



THE NATIONAL GEOGRAPHIC MAGAZINE 



more extended ruin, and secondarily for other 

 students of agriculture and economics, whether 

 in the lecture-room or in the business world. 



Geographical Essays. By William Morris 

 Davis. Edited by Douglas William John- 

 son. Pp. 777, 8 X 5^. .Boston : Ginn & Co. 

 1909. 



This is a reprint, in permanent form, of cer- 

 tain of the geographical papers of Professor 

 Davis. As the editor says in his introductory 

 note, they are reprinted without change, ex- 

 cept that a few minor modifications have been 

 made in style, and in a few cases, material 

 modifications have been made to bring the 

 matter into accord with recent discoveries. Of 

 the twenty-six ''^ssays which are here re- 

 printed, the first t'^ -Ive are educational, the 

 remainder being h" iographic in character. 

 Three of the lat:. vr originally published in 

 this Magazine. H. G. 



Descriptive Meteorology. By Willis L. Moore. 

 LL. D., Sc. D. Pp. 344. 6x9. Illustrated'. 

 New York and London : D. Appleton & 

 Co. 1910. 



In his introduction, Professor Moore char- 

 acterizes the raison 'd'etre for this book as 

 follows : 



"To provide, as far as possible, the young 

 men entering the service of the U. S. Weather 

 Bureau with a comprehensive introduction to 

 -modern meteorology. But to meet their needs 

 in this particular is to provide equally well for 

 all others who are beginning seriously this 

 important science." 



The work is divided into fifteen chapters, 

 and a summary of its contents can perhaps 

 best be given by an enumeration of their sub- 

 jects, as follows : 



The atmospheres of the earth and of the 



planets. 

 Atmospheric air. 



Micro-organisms and dust motes of the air. 

 Physical condition of the sun, and its rela-- 



tion to the earth's atmosphere. 

 Heat, light, and temperature. 

 Thermometry. 

 Distribution of insolation and the resulting 



temperatures of the atmosphere, the 



land and the water. 

 The isothermal layer. 

 Atmospheric pressure and circulation, winds. 



clouds. 

 Precipitation. 

 Forecasting the weather. 

 Optical phenomena. 

 Climate. 



The first four chapters deal to a large ex- 

 tent with matters only slightly related to me- 

 teorology, and might well be greatly con- 

 densed. To a less extent this is also true of 



the fifth chapter — that on hear, light, and tem- 

 perature. The chapter on thermometry is 

 devoted to a description of instruments and 

 their installation. The next, on insolation, 

 has a broad scope, including the distribution 

 of temperature on land and water areas, its 

 distribution in depth, both in the soil and 

 water, its vertical distribution in the at- 

 mosphere, its distribution with latitude, etc. 



The chapter on'-^the isothermal layer sums 

 up the results from a vast number of sound- 

 ings of the upper atmosphere by means of bal- 

 loons and kites. That on atmospheric pres- 

 sure begins by describing the instruments used 

 m Its measurement. This is followed by an 

 account of the general distribution of pressure 

 over the earth, the general air movements, 

 local movements, cyclonic movements, etc. 

 This subject is concluded in the next chapter, 

 that on winds, in which is included a descrip- 

 tion of the instruments used in measuring the 

 direction and velocity of air currents. The 

 chapter on clouds is brief, including their 

 classification, formation, height, etc. 



Precipitation is treated fully in all its forms, 

 as to cause, distribution in time and space, 

 modifying influences, etc., even to attempts to 

 produce it artificially. 



The application of much of what precedes 

 is made in the next chapter, that on "Fore- 

 casting the Weather," being a description of the 

 methods employed in this work in the Weather 

 Bureau. Incidental to this are descriptions 

 and explanations of many different phenomena 

 of weather. 



Optical phenomena include color of sky, 

 coronas, rainbows, halos, mock suns, etc. 



The final chapter defines climate as the aver- 

 age weather of a locality. It enumerates the 

 meteorological data which constitute climate 

 and the factors which modify and control 

 them, such as latitude, altitude, topography, 

 etc. Certain typical climates are described 

 and their effects on the human race are char- 

 acterized. 



In the above attempt to summarize the con- 

 tents of the book it must be understood that it 

 is possible to hit only the high places, as the 

 number of topics discussed is very great. 



The matter is well arranged and the book is 

 readable, a most excellent, though rare, qual- 

 ity in works on this subject. It is fully illus- 

 trated with maps and diagrams. 



At the end of each chapter is a list of books 

 treating on the subject-matter of that chapter. 



Altogether this is a most comprehensive and 

 excellent text-book on its subject. H. G. 



Across the Sahara from Tripoli to Bornu. By 

 Hanns Vischer, with foreward by Sir Harry 

 Johnston. Pp. 304, 6^ x 9. 45 illustrations 

 and map. New York : Longmans, Green & 

 Co. Price, $3.50 net. 



