460 



NA TURE 



[March 19, 1903 



the " Euichthyes," which include Plagiostomes, Teleo- 

 stomes, and Dipnoi. The order of Ganoidei is still 

 allowed to survive, and Polypterus reposes beside 

 Lepidosteus and Amia. In the treatment of Reptiles 

 a recognition of the phylogenetic relations is practi- 

 cally missed by insufficient notice of the extinct classes, 

 and Archseopteryx (der zwar kein wirklicher Vogel 

 war) is discussed under Reptiles rather than under 

 Birds. Placental mammals are dealt with in four 

 groups : — Unguiculata (the Rodents come somewhat 

 quaintly between Chiroptera and Edentates), Ungu- 

 lata, Natantia (Sirenia beside Cetacea), and Primates. 

 The strongest part of the volume seems to us to be 

 the general discussion of the structure of Vertebrata, 

 but even here the author's extraordinary restraint 

 lessens the interest of many of his paragraphs ; we 

 may refer, for instance, to what he says in regard 

 to the thyroid and the thymus. 



The figures have been designedly kept simple, but 

 they are very clear and accurate. They are for the 

 most part from original drawings, and many of them 

 are fresh and interesting. 



OUR BOOK SHELF. 

 The Analysis of Oils and Allied Substances. By A C 



Wright, M.A., B.Sc. Pp. xi + 24 r. (London : Crosby 



Lockwood and Son, 1903.) Price gs. net. 

 The book is not, nor does it profess to be, a manual 

 for the oil specialist. As a work for the student who 

 wishes to specialise and " as a laboratory guide for 

 chemists who are not extensively engaged in oil 

 analysis, or who have to deal with only a limited number 

 of oils " (to use the words of the preface), it fills a decided 

 want, and is evidently written by one who understands 

 the requirements in such a case. The first chapter, on 

 the occurrence and composition of oils, fats and waxes, 

 may at first sight appear to be superfluous, but it deals' 

 systematically with so many substances that are un- 

 familiar to those relying only on the usual chemical text- 

 books for their knowledge that it forms a really essential 

 introduction to the subsequent chapters. 



In the section on glycerin, a table of specific gravities of 

 glycerin of different strengths is given ; an error exists 

 here in the specific gravity of 40 per cent, glycerin, 1020 

 being evidently a misprint for 1-1020. 



The chapter on the chemical properties of oils, fats and 

 waxes from the analytical standpoint includes careful 

 descriptions of the methods of obtaining the so-called 

 constants ; the " ether value" is called the "ester value "— 

 a preferable term. An important comparison is given 

 of Hubl's and Wijs's methods of determining iodine 

 values. 



A chapter which contains a somewhat extended 

 description of the properties of the more important oils, 

 &c, with the methods of their investigation, is one which 

 is of especial use to those taking up the study of this 

 subject, but it is doubtful how far the author is justified 

 in saying a little, in a book of this character, on such a 

 debated question as the estimation of beef-tallow in lard- 

 one of the most difficult problems that the oil chemist can 

 have put before him. 



On the whole, the author appears to have succeeded in 

 the task he has set himself, and the subject-matter is 

 carelully brought up to date. References to original 

 papers are numerous. 



The book is very clearly printed, it is got up in very 

 readable style, and the index appears to havebeen carefully 

 compiled with a view to completeness. 



NO. 1742, VOL. 67] 



-492. 



upcre di Galileo Ferraris. Vol. i. Pp. xx 



(Milan : Ulrico Hoepli, 1902.) 

 The Italian Electrotechnical Association decided to com- 

 memorate its founder, Galileo Ferraris, by publishing 

 his collected works in three volumes, of which the 

 present contains those papers which have the most 

 intimate bearing on electrotechnics. The first, a paper 

 on the use of the compass for galvanometric measure- 

 ments, was written while Ferraris was assistant lec- 

 turer at Turin under Prof. Codazza, the second being 

 his thesis for the doctorate, on the propagation of 

 electricity in homogeneous solids, a mathematical work 

 based on methods similar to those employed by Kirch- 

 holf. The invention of the telephone by Graham Bell, 

 about the year 1877, attracted the attention of Ferraris, 

 who was not slow to read a paper at the Turin Society 

 of Engineers, and to find in the new instrument a means 

 of testing Helmholtz's theorem, according to which the 

 timbre of a sound does not depend on the phases of its 

 components. Another paper is on the intensity of the 

 currents in the telephone. His two elegant theorems 

 on the distribution of constant currents, published in 

 (879, follow. The introduction of secondary generators 

 or transformers, in 1884, paved the way for his classical 

 memoirs on the Gaulard and Gibbs transformer, on the 

 difference of phase and dissipation of energy in trans- 

 formers, on some results of experiments with the Ganz 

 transformer, invented by Zipernowskv, DeVi, and 

 Blathy, and an interesting correspondence with Dr. 

 Hopkinson. The alternating current motor forms the 

 subject of the next two papers, and the volume con- 

 cludes with his treatise on the geometry of vector fields, 

 which was published after his death. This paper affords 

 an example of the spirit in which Ferraris devoted him- 

 self to science. His successes as an applied electrician, 

 so far from drawing him aside from theoretical work, 

 seem to have stimulated him to advocate the pursuit of 

 research for its scientific value. From the introductory 

 sketch of his work by Prof. Guido Grassi, we quote the 

 following words : — " Whoever, in scientific researches, 

 always has applications in view never discovers any." 

 Again, at the second conference on electric lighting, in 

 referring to the patient workers that had established 

 the conditions for resolving economically the problem of 

 illumination, Ferraris remarked : — " These men never 

 thought of applications, and it is for tliis reason tliat 

 they discovered tlicm ; they performed the part most 

 important for applications, thev provided the applicable 

 things.'-' 



.4 Text-book of Field Astronomy for Engineers. By 

 G. C. Comstock. Pp. x + 202. (New York : Wiley 

 and Sons; London: Chapman and Hall, Ltd., 

 1902.) Price 10s. 6d. 

 This text-book is designed for the considerable class of 

 technical students who need to make practical applic- 

 ations of the methods of spherical astronomy, but can- 

 not devote to the subject the time necessary for a course 

 such as befits those who wish to study astronomy as 

 a science. Teachers who have to undertake the in- 

 struction of such students will study with interest the 

 course which Prof. Comstock has adopted after an 

 experience extending over many years, more especially 

 as no attempt is made to reduce the work to mere rule- 

 of-thumb processes. The introductory chapters include 

 the necessary formula; for the solution of spherical 

 triangles, hints on the orderly arrangement of compu- 

 tations, definitions of coordinates, and a short account 

 of the various corrections to observed data. The 

 methods of observation are classified as rough, approxi- 

 mate and precise according to the degree of accuracy 

 required, and this excellent arrangement not only 

 simplifies the task of the student, but indicates how 

 lime may often be saved by avoiding the more refined 



