June i6, 1910] 



NATURE 



457 



as "Starch and Isomers" in the list of contents, and 

 as " Starch and its Isomerides " above the text of the 

 section itself. Finally, the book is described as 

 "printed in America." Printers in the United States 

 do not apparently believe that " the whole is greater 

 than its part." T. A. H. 



TROPICAL CLIMATOLOGY. 

 Handbuch der KlimatoJogie. By Prof. Julius 

 Hann. Band ii., Klimatographie. i Teil, Klima der 

 Tropenzone. Dritte, wesentlich umgearbeitete and 

 vermehrte Auflage. Pp. xii + 426. (Stuttgart: J. 

 Engeihorn, 1910.) Price 14 marks. 



THIS is the first part of vol. ii. of the third 

 edition of Prof. Hann's "Handbuch der Klimato- 

 logie." Vol. i. dealt with general principles, and 

 we now come to the detailed consideration of the 

 climates of different parts of the world. The volume 

 before us concerns itself with the tropics, the con- 

 sideration of temperate and polar regions being re- 

 ser\^ed for subsequent volumes. The author has not 

 confined himself strictly to the area lying between 

 23^° north and south of the Equator. When desirable 

 he has gone outside this region. Roughly speaking, 

 he discusses that portion of the earth's surface which 

 has an annual mean temperature of 20° C. or above. 

 The isotherm of this value ma}' be taken as marking 

 the polar limits of the trade winds, when definable, 

 and of the palm tree. 



A great part of the book is taken up with tables, 

 interspersed with descriptive paragraphs taken from 

 the writings of travellers or residents in the regions 

 under review. The tables refer for the most part to 

 the elements, temperature, and rainfall, but where 

 the data are available, tables of wind direction fre- 

 quency, humidity, cloud amount, and pressure are 

 added. The additional matter incorporated since the 

 second edition appeared in 1897 is considerable. For 

 some areas the author has had the advantage of con- 

 sulting works such as Captain Lyons's " Physiography 

 of the Nile Basin," but for others he has had to go 

 into the byways of meteorological literature. The 

 labour involved in collecting and working up the 

 scattered fragments must have been prodigious even 

 for so indefatigable a worker as Prof. Hann, and we 

 can but admire and marvel at the thoroughness with 

 which the task has been completed. Much time has 

 been expended over the calculation of true means of 

 temperature from daily extremes or from readings 

 at fixed hours. Even so. Prof. Hann regards many. 

 'he values as still uncertain, but in the absence of 

 quate knowledge of the course of the diurnal 

 variation, no more can be done at present. 



The introductory chapter discusses the general 

 characteristics of tropical climate. A special section 

 is devoted to its physiological action on the human 

 organism, particularly that of the white man, and 

 affords an opportunity of referring to the recent 

 advances in the domain of tropical medicine. After 

 that we are introduced successively to West Africa 

 and the Congo, East Africa with the Sudan, the mon- 

 soonal area of Asia and northern Australia, the Pacific 

 islands, and finally to tropical America. 

 NO. 2120, VOL. 83] 



OUR BOOK SHELF. 



The Fourth Dimension Simply Explained. Edited by 

 Prof. H. P. Manning. Pp. 251. (New York: 

 Munn and Co., Ltd., 1910.) Price 1.50 dollars net. 

 There are few fallacies which have done more to mis- 

 lead the unscientific public than the misconception 

 known as the fourth dimension. The use of this term 

 is calculated to convey the false impressions, first, 

 that hypergeometry is limited to space of four dimen- 

 sions instead of being extended to space of « 

 dimensions where n is any positive integer; second, 

 that even not going beyond tour dimensions, there is 

 one particular coorainate called the fourth dimension 

 which stands out from the rest, and alone is worth 

 considering. 



Now so long as we regard four-dimensional space 

 as a geometrical conception, there is no difference 

 between its fourth dimension and its first, second, and 

 third dimensions, just as in ordinary solid geometry 

 there is no third dimension distinguishable in any 

 respect from a first and second dimension. On the 

 other hand, as soon as we introduce the concept of a 

 fourth coordinate differing essentially from the other 

 three, this coordinate ceases to be a geometrical con- 

 ception, and may be taken to represent time, density, 

 or anything else we like. 



Some American who had some money to get rid 

 of and had no better use for it offered, in the 

 Scientific American, a prize of 25/. for the best popular 

 explanation of the fourth dimension, and the present 

 volume is a collection of selected essays that were 

 submitted in the competition, with an introduction by 

 Dr. Henry P. Manning. It must be admitted that 

 what the authors have written is mostly sensible and 

 reasonable enougii, and in no way contradicts the re- 

 marks that have been made above. If the book had 

 been brought out under the title " Hyperspace Simplv 

 Explained," and the titles of those essavs where the 

 words occur had been altered by the substitution of 

 " four " for " the fourth," the utility of the book would 

 have been considerably increased. It contains very 

 little that can be described as unscientific. 



Diagram showing the Classification of the Elements : 

 Periodic Arrangement. Size 44x68 inches. (Lon- 

 don : Baird and Tatlock, Ltd.) Price, mounted on 

 cloth, rollers, and varnished, 255. 

 The "periodic" classification of the elements plays 

 such an important part in courses of inorganic chem- 

 istr\f for students that a large wall diagram illustrat- 

 ing this classification has now become a prominent 

 feature in the equipment of the chemical lecture 

 theatres of colleges and technical institutions. Such 

 diagrams have usually had to be prepared by the staff 

 of the department concerned. Many teachers of 

 chemistry will therefore welcome the issue of a large 

 printed chart, suitably mounted on stout linen, 

 giving the usual periodic classification of the elements 

 with their names and atomic weights. The lettering 

 is bold and clear, although, perhaps, a little wider 

 spacing might have been allowed with advantage. 



The "chart fails to show, however, the differentiation 

 of each vertical group into " odd " and " even " series. 

 From a teaching point of view there is much to be said 

 for placing the helium and argon group of elements 

 before the alkali group and not after the halogens. 

 The method of classification used for the iron-platinum 

 group is perhaps not quite the most satisfactory* one, 

 though this is, of course, at present largely a matter 

 of individual opinion. The chart as a whole would 

 probably gain in clearness by replacing in future 

 issues the names of the elements by their customary 

 symbols. 



