September 15, 1923] 



NA TURE 



;89 



Throughout the book^ adequate reference is made 

 to the diseases caused by animal parasites, and to the 

 methods employed for controlling the latter. With a 

 few exceptions, the illustrations are good, and they 

 possess the commendable feature that, where the 

 organism is not drawn of the actual size, the magnifica- 

 tion used is always indicated. 



It is to be hoped that this excellent book will help 

 to arouse a more general interest in a subject with 

 which all are personally concerned. Although it is 

 written in a popular style, the book is always accurate ; 

 any one who reads it carefully will acquire the founda- 

 tion of a good general knowledge of the animal parasites 

 of man, and, if he wishes to pursue the subject further, 

 he will find that he has nothing to unlearn. 



H. J. Walton. 



Our Bookshelf. 



Spezieller Kanon der zentralen Sonnen- und Mond- 

 finsternisse, welche innerhalb des Zeitraums von 600 

 bis 1800 N. Chr. in Europa sichtbar waren. Von 

 J. Fr. Schroeter. Pp. xxiv + 305 + cl Tafeln. 

 (Kristiania : Jacob Dybwad, 1923.) 



In this volume Schroeter continues Ginzel's " Spezieller 

 Kanon der Sonnen- und Mondfinsternisse " (1899), 

 which contained all eclipses visible in an area between 

 10° W. and 50° E. of Greenwich, and between 

 30° and 50° N. latitude, from 900 B.C. to a.d. 600. 

 Schroeter's scope is somewhat different. He gives all 

 central eclipses of the sun and all total eclipses of the 

 moon visible in Europe between a.d. 600 and 1800. 

 For partial eclipses of the moon between those dates 

 it is still necessary to turn to Oppolzer. It will be 

 observed that the area covered by Schroeter differs 

 widely from that covered by Ginzel, and results from 

 the substitution of a European for a Mediterranean 

 civilisation. One result of this selection is that the 

 present volume is of little use for the study of the 

 numerous eclipses recorded in the history of non- 

 European countries. Perhaps some day each continent 

 will have its own equivalent to Schroeter. 



The elements of eclipses used in this volume are based 

 on the same constants and computed by the same 

 formulae as those determined by Ginzel and used in 

 his " Spezieller Kanon," but the errors attaching to 

 the results are far less at the dates for which these 

 tables are constructed than for the distant dates with 

 which Ginzel deals. One advantage of Schroeter's. 

 volume over Ginzel's is that, while an exact computation 

 from Ginzel's elements can only be made by reference 

 to the formulae contained in Oppolzer's " Canon der 

 Finsternisse," Schroeter prints these formulae in his 

 introduction. Another difference is that where Ginzel 

 contents himself with computing the northern and 

 southern limits of the total or annular phase of a solar 

 eclipse, Schroeter computes also the curves of nine 

 digits magnitude. Again, while Ginzel has one large- 

 rale map showing all the zones of total and annular 

 eclipses for each century, Schroeter, though hmiting 

 himself to a smaller scale, has a separate map for each 

 eclipse. There is, however, nothing in Schroeter to 



NO. 281 I, VOL. I 12] 



correspond to the detailed discussion of each historical 

 eclipse which is one of the most valuable features of 

 Ginzel's work. 



This work is likely to be of more use for historical 

 than for astronomical studies. Probably it will be 

 used mainly by those astronomers who may be called 

 upon to assist students of history. 



Modern Gas Producers. By N. E. Rambush. Pp. 

 xix + 545. (London: Benn Bros., Ltd., 1923.) 

 555. net. 



We have nothing but commendation for this treatise 

 on modem gas producers. It is a finely conceived work 

 admirably executed. The author is one of the few 

 equipped with theoretical knowledge of the thermal 

 processes involved in producer gas manufacture, and 

 with the extensive acquaintance with technological 

 aspects of the matter required for an adequate treatment 

 of the subject. Of this, the work before us is sufficient 

 witness. Four sections devoted respectively to (i) 

 the theory of the formation of producer gas, (2) types 

 of gas producers, (3) control and operating principles 

 of producer gas plants, and (4) the utilisation of producer 

 gas, are comprised in the book. The theory of the 

 subject is developed in an extremely clear manner. We 

 think the author has succeeded in his declared endeavour 

 to describe plants and types of producers quite im- 

 partially. A rather careful reading of the work has 

 left us quite undecided as to what plants the author 

 has been personally connected with in a professional 

 capacity. This is eminently desirable in a work of this 

 nature, and in marked contrast to what we have found 

 in at least one volume of the present series of publica- 

 tions. Specific features of design commonly employed 

 in practice and of a number of special designs are set 

 out in considerable detail. This section might easily 

 have degenerated, as has happened in too many cases 

 recently, into a highly priced trade circular. It has 

 not done so, but is extremely readable and informative, 

 and contains much valuable data relating to actual 

 trials of the various plants. The third section is com- 

 mendably brief, as fuller particulars of the testing of 

 fuel and gas are contained in another volume of the 

 same series. Typical applications of producer gas in 

 the gas engine, gas turbine, furnaces, etc., and the 

 relative efficiencies in use of various grades of gas, are 

 briefly treated in the last section. 



The work is characterised by a number of extremely 

 valuable tables and graphs facilitating calculation. 

 There are altogether 356 drawings and illustrations, all 

 beautifully executed and reproduced. An adequate 

 index is provided. We think the high price of the 

 volume justifiable, and prophesy an assured premier 

 position for the work in the hterature of producer gas 

 technology. J. S. G. T. 



Department oj Scientific and Industrial Research. 

 Report of the Fuel Research Board for the Years 1922, 

 1923. First Section : The Production of Air-dried 

 Peat. Pp. vii + 146. (London : H.M. Stationery 

 Office, 1923.) 55'. net. 



Mechanical methods of winning peat in operation in 

 Europe afnd Canada are dealt with in this report, 

 in which are discussed the difficulties encountered in 



wiiiniiiL; the ;iir ili'icd tucl, .mil possible schemes for 



