November i6, 1888.] 



SCIENCE. 



235 



horse-power engines will soon be erected, and will drive two Fer- 

 ranti dynamos, each capable of supplying current for 25,000 lamps. 

 These are the largest electric generators in the world, and we can 

 get some idea of the increasing size of dynamos when we remember 

 that four years ago the largest practical machines were Edison's 

 ' Jumbo ■ dynamos of 1,200 lights capacity. In the second engine 

 room will be placed two sets of engines and dynamos. These are 

 combined in such a manner that the armatures of the dynamos are 

 driven directly by the engines and act as their fly-wheels. The 

 speed is but sixty revolutions per minute. There will be four dy- 

 namos, and they will finally have each a pair of 10,000 horse-power 

 engines. At present they are to have but 5,000 horse-power each. 

 All future extensions of plant will be in these units. The dynamos 

 will weigh 500 tons, and the armatures will be 45 feet in diameter. 



The distribution will be on the alternating current system. The 

 current leaves the station at the enormous potential of 10,000 volts, 

 and is taken to a number of distributing stations where a first con- 

 version takes place, lowering the potential to one or two thousand 

 volts; then it is taken to the points of consumption, where a sec- 

 ond conversion takes place and the voltage is lowered to that nec- 

 essary for the lamps. 



The main cable, 2f inches in external diameter, is formed of two 

 concentric tubes of copper. An insulating compound separates 

 the two tubes, the central portion of the cable being hollow : the 

 sectional area of each tube is .5 of a square inch. 



The first two dynamos of 1.500 horse-power each are nearly 

 completed, and will soon be erected ; two of the 10,000 horse-power 

 dynamos will probably be finished in about five months. The 

 space now covered with buildings will accommodate 40,000 horse- 

 power, and the rest of the space available can accommodate 80,000 

 horse-power more, a total capacity of 120,000 horse-power. 



This station, in capacity and the enormous potential used (the 

 maximum electromotive force is about 15,000 volts), far surpasses 

 any thing that has been attempted in this country or anywhere else. 

 It is hardly to be hoped that the scheme will succeed without great 

 trouble and discouragement at first, since many of the conditions 

 are new ; but whether it finally fails or succeeds, the experience it 

 will give will be of great benefit to electricians. 



Electro-deposited Copper. — Messrs. Elmore, in England, 

 have introduced a process for the production of pure copper tubes, 

 wire, etc., by which very satisfactory results have been obtained. 

 The general method of producing a tube is to immerse a revolving 

 mandrel, nearly surrounded by bars of Chili copper, in a bath of 

 copper sulphate, and send a current of electricity between the bars 

 and the mandrel. The ordinary result would be the deposition of 

 crystalline copper, with little adhesiveness and strength. The es- 

 sential feature of the process is a burnisher pressing lightly on the 

 surface of the copper, travelling on a leading screw from one end 

 of the mandrel to the other, its motion being automatically reversed 

 when it reaches either end. The result is a tube of great density 

 and strength, and without lines of weakness as in ordinary tubes. 



When it is desired to make wires, tubes of any desired length 

 and thickness are cut spirally into square wires, and these are after- 

 wards drawn to the required size and shape. The conductivity is 

 greater than that usually obtained in commercial wire, and is even 

 greater than that of the samples determined by Dr. Matthiessen, 

 who used the greatest care in obtaining his specimens of copper. 

 Tests made on annealed and hard-drawn wires give respectively 

 102.4 and 104.44 per cent of the conductivity obtained by Dr. Mat- 

 thiessen for pure copper. 



BOOK-REVIEWS. 



Researches on Diamagnetism and Magne-Crystallic Ach'on. By 

 John Tyndall. New York, Appleton. 12°. S1.50. 

 When Tyndall undertook the first of the researches contained 

 in this volume, the attention of physicists had been drawn to the 

 remarkable phenomena exhibited by certain substances, metals, 

 and other matter, and by crystals when placed in a magnetic field. 

 It was found that various substances, notably bismuth, were re- 

 pelled by magnetic poles instead of being attracted ; and it was 

 stated that crj-stals in a magnetic field tended to take up a definite 



position, but were neither attracted nor repelled. With respect to 

 the first of these phenomena, the questions which arose were, 

 ' What is the nature of this diamagnetic force? ' 'Does it corre- 

 spond to inagnetic force but with an opposite direction ? ' Faraday 

 first thought that the phenomena might be explained by assuming 

 in diamagnetic bodies a polarity the reverse of that in magnetic 

 bodies ; but he soon abandoned this view, and held that the appa- 

 rent diamagnetism of bodies was caused by their being less mag- 

 netic than the medium in which they were placed. A diamagnetic 

 body was with him a body less magnetic than air. 



Tyndall, in these memoirs on the subject, has with great ingenu- 

 ity, and with apparatus at once powerful and delicate, compared 

 the deportment of diamagnetic with magnetic bodies ; and " the 

 antithesis between them, when acted on by all possible combina- 

 tions of electro-magnets and electric currents, was proved to be 

 absolute and complete. ... No reasonable doubt, therefore, 

 could rest upon the mind that the diamagnetic force possessed pre- 

 cisely the same claim to the title of polar force as the magnetic." 



This work of Tyndall's was done over thirty years ago. The 

 attention of physical scientists was called to other electrical and 

 magnetic phenomena, and no really important experiments on 

 magnetization were tried until 1872, when Stolltow and Kowland 

 published their well-known researches. But in the last few years 

 interest has again centred in magnetic phenomena, and it is well 

 that attention should be called to earlier experiments. 



The present edition of • Diamagnetism and Magne-Crystallic 

 Action ' differs from the original in the omission of some parts 

 that are of little interest now. As a clear description of difficult, 

 ingenious, and successful experiment, it should form part of the 

 library of every physicist. 



Tales of the Birds. By W. Warde Fowler. London and New 

 York, Macmillan. 12°. $2.50. 



This book is hard to classify, being a series of eight fancy 

 sketches, consisting of imaginary bird-talk, with little obvious 

 point, and containing little that can be seriously called ornithologi- 

 cal. It is designed, perhaps, to illustrate certain incidents of bird- 

 life, as the hard struggle for existence of English field-fares in win- 

 ter, the dangers and mishaps befalling birds during migration, etc. 

 The birds are supposed to tell their own tales. The slight web of 

 fact is heavily padded with light fancies, designed doubtless to in- 

 terest especially juvenile readers, who may find the book some- 

 what attractive. The book is English in its scenes and subjects. 

 The writer is obviously familiar with bird-ways, and might write 

 well in a more serious vein. The eight full-page illustrations are 

 quite in keeping with the general character of the text. The title 

 of the book is about all that would suggest its classification as a 

 natural-history publication. 



A Manual of the Vertebrate Animals of the Northern United 

 States. By David Starr JORDAN. 5th ed. Chicago, A. 

 C. McClurg & Co. 12°. S2.50. 

 The present edition of President Jordan's well-known ' Manual ' 

 is much enlarged in scope, and so completely rewritten and re- 

 arranged as to be in many respects not only greatly improved, but 

 practically a new work. The geograpical area is extended westward 

 from the Mississippi River to the Missouri River, and the marine forms 

 (excludmg the deep-sea species and those of merely accidental occur- 

 rence) are for the first time included, the coast region thus covered 

 extending from Nova Scotia to Cape Hatteras. The artificial keys of 

 the former editions have in great part given place to analytical keys 

 based on differential characters. While this change may render 

 slightly more difficult the quick recognition of species by the inex- 

 perienced student, it has the advantage of making known more 

 clearly the actual basis of classification. The order of succession 

 of groups is also reversed, the lowest or more generalized standing 

 first ; the ' Manual ' beginning with the fishes, and ending with the 

 mammals. By the omission of synonymes and references, except 

 in special cases, the use of smaller type and a larger type-bed, the 

 amount of matter has been much increased, while the number of 

 pages is lessened and the typographical appearance of the book 

 greatly improved. In classification and nomenclature the work is 

 fully abreast of the latest discoveries and conclusions in respect to 



