March 3, 192 1] 



NATURE 



sary for artillery work, gathered during two years 

 spent as Chef de Brigade Topographique. No 

 claim is made to the production of a complete 

 text-book of surveying; the author's limited ex- 

 perience would preclude that; and, as will be 

 naturally understood, the practised surveyor has 

 little to learn from this volume. The only point 

 where it may possibly be of service in supple- 

 mentation to more complete treatises is in the 

 discussion given of the problem of resection, par- 

 ticularly of resection from more than three points, 

 a problem somewhat neglected by English writers. 

 A fervent claim is made to the superiority of the 

 centesimal division of the quadrant, which, it is 

 held, offers practical advantages, such that, once 

 used, it is hard to understand how its merits can 

 be doubted ; " one returns with difficulty to the 

 sexagesimal division." However this may be, the 

 subject is now beyond discussion, there not being 

 the remotest chance of the use of the centesimal 

 system spreading outside the pale of the Service 

 gtographique de I'Arm^e. Even admitting that 

 there are some gains in facility of computation, 

 we think these dearly purchased at the cost of 

 this isolation. 



A recommendation is made that when taking 

 out the number corresponding to a given 

 logarithm a table of antilogs should be used, 

 and it is regretted that no such table, extending 

 to more than four decimal places, has been pub- 

 lished. This must be read as meaning published 

 in France. Such tables are common here, and 

 an excellent little set of five-figure tables, includ- 

 ing antilogs, is (or was?) procurable at the 

 modest price of sixpence, while Filipowski's seven- 

 figure tables are well known. They are not more 

 generally employed solely because computers find 

 that, on the whole, the use of the simple log table 

 IS preferable. E. H. H. 



Basic Slags: Their Production and Utilisation in 

 Agriculture. (Reprinted from the Transactions 

 of the Faraday Society, vol. xvi., part ii., 1920.) 

 Pp. 259-335. (London : The Faraday Society, 

 n.d.) 75. 6d. 

 This full report of the discussion organised by 

 the Faraday Society last March on the utilisa- 

 tion of basic slag in agriculture forms a con- 

 venient little booklet which agricultural lecturers 

 and experts will find of considerable value. 



The necessity for the discussion arose out of 

 the change in the manufacture of steel which 

 began before the war, but has proceeded at an 

 increasing rate in the past few years. In conse- 

 quence, agriculturists no longer obtain the slag 

 to which they have been accustomed, and which 

 was used in the classical experiments that have 

 passed into agricultural tradition ; they obtain 

 instead something completely different under, how- 

 ever, the same name. An account of the discus- 

 sion was reported in Nature of April 8, 1920 

 (p. 183). 



From the agricultural point of view there is an 

 interesting account of the field trials with the new 



NO. 2679, VOL. IO7I 



slags, which suggests for them a better value 

 than was first expected' from the chemical 

 analysis. On the works side the report does not 

 make very hopeful reading ; no easy way could 

 be found for increasing the phosphorus content 

 of the slag, apart from the simple addition of 

 mineral phosphates, which would be quite unneces- 

 sary. 



The meeting was useful, and the publication 

 of the papers will . prove even more so, as 

 it will enable a wider circle to appreciate the 

 present position of the basic slag problem. It is 

 gratifying to know that, as the direct outcome 

 of the discussion, the Ministry of Agriculture set 

 up a Committee of steel-makers and agriculturists 

 to go into the question of the improvement of 

 basic slag, and to report on any action that could 

 be taken. The Committee is presided over by 

 Dr. E. J. Russell, of the Rothamsted Experi- 

 mental Station, and is understood to be pursuing 

 its inquiries with a view to an early report. The 

 Faraday Society is to be congratulated on the 

 success of its efforts. 



Les Variations et leur HerdditS ches les Mol- 

 lusques. By Paul Pelseneer. (M6moires de 

 r Academic Royale de Belgique, Classe des 

 Sciences, Collection in-8°. Serie II., torn, v.) 

 Pp. 826 ; 286 illustrations in the text. (Brussels, 

 1920.) 

 Cut off from the sea, his library, and his labora- 

 tory at Ghent, that doyen of malacologists, Dr. 

 Paul Pelseneer, during the German occupation of 

 Belgium, fell back on his note-books and such 

 material as lay to his hand, and has put together 

 a fine volume that will be a work of reference for 

 practically all time. 



The variations observable in the MoUusca have 

 never hitherto been systematically studied as a 

 whole. Dr. Pelseneer now takes them up seriatim 

 as they occur in the shell, in the external features 

 of the animal, and in the various internal organs 

 and their systems (circulatory, respiratory, nerv- 

 ous, etc.), plentifully quoting original observations 

 in addition to his own, and illustrating the whole 

 with reproduced and new figures. He classes these 

 variations and discusses their interrelationships, 

 individual and specific, in different organs, their 

 cause, especially when due to environment, and 

 finally their heredity. 



It is impossible within the limits of a short 

 notice to summarise even the author's conclusions : 

 the work itself must be consulted. When, how- 

 ever, he states that there is no example in the 

 MoUusca of preadaptation, we venture to think 

 he must have overlooked the case of the myophore 

 in Velates, and of the dorsal depression in the 

 shell of the young Nautilus, which later on re- 

 ceives the ventral curve of the preceding whorl, 

 as pointed out by Hyatt in his "Phylogeny of an 

 Acquired Characteristic." 



The book is touchingly dedicated " A la m^moire 

 de mes Compatriotes victimes de 1 'agression Alle- 

 mande (1914-1918)." B. B. Woodward. 



