39- 



NA TURE 



[June 3, 1909 



Osmundaceae have recently acquired a remarkable 

 interest from the researches of Kidston and Gwynne- 

 \'aus:han, who have succeeded in tracing back this 

 family, on anatomical evidence, to a common origin 

 \\ith the Palaeozoic Botryopterideae. The adder's 

 tongues, on the other hand, have been separated from 

 the ferns by some authorities. The author lays stress 

 on the relations of this family to the Sphcnophyllum- 

 Psilotum type, as well as to the ferns and 

 • Cycadofilices. 



Lecture i.\. is occupied partly with the filicinean 

 leaf-trace, partly with the development of the vascular 

 ■ system in the individual plant (ontogeny). In intro- 

 ducing the latter subject an interesting comparison is 

 drawn between animal and vegetable embryology 

 (p. i2>). 



In the final lecture the vascular system of the ferns 

 is compared with that of Other phyla of vascular 

 plants. A valuable criticism of Prof. Jeffrey's pro- 

 posed division of the higher plants into Lycopsida and 

 Pteropsida is given in this connection. Sections on 

 the morphological construction of Selaginella com- 

 pared with that of the ferns (with which a remarkable 

 analogy is ingeniously traced), and on the relations of 

 ferns and seed-plants, conclude the course. 



The book is an admirable example of the evolu- 

 tionary treatment of the anatomical structure of 

 plants, a line of research in which English-speaking 

 botanists have for some time past taken the lead, the 

 author himself being one of its best exponents. 



We have only one verbal criticism to add; it is a 

 pity that the author lends his sanction to the misuse 

 of the word hypothecate, now becoming frequent 

 among certain of the younger writers of scientific 

 papers. He speaks of " such an ancestor as we have 

 hypothecated " (p. 6). We have learnt from .Sir W. S. 

 Gilbert that ancestors may be bought, but it was 

 reserved for the modern botanical author to discover 

 that they may be mortgaged ! 



A glossary, bibliography, and index complete the 



D. H. S. 



volume. 



ELECTRICAL ENGINEERING. 

 Heavy Electrical Engineering. By H. M. Hobart. 

 Pp. xxiv + 338. (London: A. Constable and Co., 

 Ltd., 1908.) Price 16s. net. 

 "117' IT H so prolific an author as Mr. Hobart, the 

 ^ * expectation of finding in any new book a good 

 deal of old matter in a new guise is but natural, but 

 in the present case such an expectation would be quite 

 erroneous. This book is original from beginning to 

 end; moreover, it is a perfect store of useful practical 

 data and is clearly written, so that the reader always 

 remains in touch with the author and knows what 

 point he wishes to make. These points are not 

 matters of little detail, but the features in a design 

 which really count. It is this ability of Mr. Hobart 

 to take a broad and comprehensive view of his subject 

 which makes this book so eminently readable. But in 

 parts it is also highly controversial, and although also 

 these parts are interesting reading, one cannot help 

 feeling a little anxious for the author lest he should 

 NO. 2066, VOL. So] 



prove a false prophet. Thus he calls the London, 

 Brighton and .South Coast electrification " tliis single- 

 phase monstrosity," and devotes several pages to 

 prove that the work could have been done for two- 

 thirds the money on the direct-current system and in 

 much less time. It may be that he is right, but if 

 one remembers that the Swiss railway committee, 

 which has been deliberating for three years, has not 

 yet taken heart to condemn the single-phase system 

 root and branch as Mr. Hobart does, a saying about 

 a region where angels fear to tread comes to one's 

 mind. .Another point on which the author is equally 

 dictatorial in his judgment concerns the transmission 

 of power by high-pressure continuous current on the 

 series system. 



The general scope of the work is excellent. The 

 author takes in succession all the parts of a large 

 electricity supply undertaking, and shows us the 

 determining factors and their relative importance in 

 the right perspective. The metric system is used 

 throughout, and as unit of power the kilowatt. As 

 unit of energy the author uses the kilowatt-hour, 

 whether the energy be mechanical or heat. Thus we 

 find even such quantities as the specific heat and the 

 latent heat of steam expressed, not in calories, but in 

 kilowatt-hours. As the unit mass to which these 

 quantities arc referred he takes one metric ton of 

 steam or water. In the first two introductory chapters 

 are given tables on the property of steam in the new 

 measure, evaporative power, cost and calorific value 

 of coal, the over-all efficiency of generating stations, 

 an analysis of the losses, the plant capacity in various 

 stations, the demand for light, power, and traction in 

 various towns, &c., all from actual experience and 

 carefully tabulated. He then shows by way of example 

 how the figures collected may be used to design an 

 electricity works for a town of one million inhabitants, 

 and comes to the conclusion that the immediate 

 demand would be for 77 million kilowatt-hours per 

 annum, and the demand in the course of the next ten 

 years 120 million kilowatt-hours. The works should, 

 therefore, be designed with the view of an extension up 

 to this limit. With chapter iii. and subsequent chapters 

 we enter into the more technical part of the subject, 

 namely, steam-raising plant, engines and turbines, 

 generating machinery, condensing plant, and the gene- 

 rating station considered as a whole. This brings us 

 to chapter viii., which deals with overhead lines and 

 underground cables, whilst the last two chapters are 

 devoted to a criticism of the Thury system and to 

 electric traction. 



Most of what the author has to say on steam 

 engines is concerned with turbines, and very 

 little is said about piston engines. Neither does 

 the author discuss the advantage of combining 

 the piston engine with the turbine in the 

 sense that the former utilises the high-pressure 

 steam and exhausts into the latter. His ideas as to 

 the ultimate size of turbine sets are on a grand scale. 

 He thinks that units of 10,000 to 20,000 kw. at 

 pressures up to 20,000 volts will come into use. 

 Curiously enough, he says nothing about the question 

 of how sets of this magnitude are to be kept cool. It 



