424 



NA TURE 



[August 30, 1894 



adjuncts. It is an excellent small book, suitably 

 illustrated. 



(3) This is described as an '• attempt to provide an ele- 

 mentary book for those who are intending to enter the 

 profession of electrical engineering.'' In a very enter- 

 taining and humorous preface the author at once enlists 

 the sympathy of the ordinary reader in general, and of 

 the reviewer in particular. After its perusal the latter 

 feels prepared to find much that is novel in treatment and 

 revolutionary in substance in the work itself, but he finds . 

 that his anticipations are only realised to a moderate 

 degree. The so-called "Inductive Circuit" is easily 

 recognised as an old friend under a new name. The 

 equation of the condenser, usually written 



Quantity = Capacity x Potential-DifTerence, 



is given by the author in the form 



Accumulation x Resist.ince = Electrical Pressure, 



wherein he regards inductive resistance as bearing the 

 same relation to capacity that electrical resistance does 

 to electrical conductivity. The only advantage we can 

 see in this notion is that it brings out clearly the fact 

 that condenser capacities combine according to the same 

 law as electrical conductivities. Again, the author 

 imagines the " sapient critic " to laugh at his views of 

 "loops" and" unlooping" in connection with the lines 

 of force of a magnetic field, and puts a question to him 

 which he evidently regards as a poser of the first water. 

 He says : " Your teaching involves cutting here, there, 

 and everywhere — first in this direction, then in that ; but 

 though you tell us what happens when you cut ' lines of 

 force,' you say nothing of what happens when your con- 

 ductor leaves those lines of force. You bring your con- 

 ductor to be acted upon by lines of force, but although 

 you also take your conductor from those lines of force, 

 you recognise no reverse action. All your cry is ' Cut,' 

 'cut,"cut,'&c.,&c." 



This is of course veritable moonshine. Every elec- 

 trician is aware that every line of force forms a closed 

 loop, and that "cutting" necessarily involves looping 

 or unlooping, as the case may be, and vice versa, when- 

 ever the conductor forms a closed circuit. 



The first principles of the dynamo arc clearly and 

 accurately given, though a worse illustration than that of 

 agramme ring on p. 152 is not often to be seen. How- 

 ever, it is good to see a clear distinction between 

 "energy" and the "rate of its production," all the 

 more noticeable by reason of its rarity in recent elec- 

 trical books. 



Notwithstanding its eccentricity, the book will be 

 useful to a certain class of student. 



(4) Mr. Kilgour considers scientifically the design of 

 systems of distribution which shall give maximum 

 economy with satisfactory working results. This sub- 

 ject was initiated by the valuable papers of Lord Kelvin 

 and of Profs. Ayrton and I'erry. In 1881 the former 

 considered the problem of finding the cross-sectional 

 area of copper required for a conductor to transmit a 

 given current in order that the total annual expenditure 

 for the energy wasted in the conductor, and for interest, 

 depreciation, and repairs on the conductor should be a 

 minimum. This problem is now historical. It was on 



NO. 1296, VOL. 50] 



this occasion, the meeting of the British Association in 

 the year mentioned, that Lord Kelvin first brought before 

 engineers the fact that the relation between the size of 

 the conductor and the current strength should be governed 

 by economical considerations. As stated by Mr. Kilgour, 

 six quantities are involved in an important manner, viz. : — 

 \', the pressure in volts at end of feeder near to genera- 

 tors ; V, the pressure in volts at end of feeder remote 

 from generators ; C, the current strength in amperes 

 flowing through the feeder; P, the watts delivered to 

 feeder ; p, the watts delivered by feeder ; and .r, the 

 cross-sectional area in square inches of the copper of 

 feeder. These six quantities are obviously connected 

 by three relations ; we may further assume two other 

 relations between them, and then a sixth relation deduced 

 from economical considerations suffices to determine the 

 whole of the six quantities. The two assumed relations 

 may take the form of two of the quantities being given. 

 This is what usually happens, and is always the case in 

 the author's discussion. Of the fifteen possible cases 

 Lord Kelvin investigated, that in which t' and C are 

 given ; Prof Ayrton, that in w hich V and C, and also 

 that in which V and x are given ; while Prof. Ayrton and 

 Perry, in conjunction, before the Society of Telegraph 

 Engineers and Electricians in 1SS6, considered V and p 

 to be given quantities. The remaining eleven cases are 

 completely examined by Mr. Kilgour, and in doing so, as 

 well as by giving a clear exposition of the whole subject, 

 he has rendered valuable service. To all those who are 

 concerned with the design of systems of distribution, this 

 part of the work will be found to be of high interest and 

 usefulness. In Part ii. will be found a collection of de- 

 scriptions of the systems which practical men have 

 gradually evolved by knowledge and experience. The 

 best mains and culverts, and also the means of main- 

 taining them in a state of efficiency, in use in England 

 and on the continent, are described in detail with a large 

 number of excellent illustrations. The compilers have 

 shown good judgment in the selections they have made 

 from the many systems that have been adopted. 



( 5) This work is intended to afford to County Councillors 

 and others similarly placed some information likely to be 

 of use to them in dealing with questions of central station 

 lighting. It is a small and unpretending work of some 

 forty pages, and seems to have accomplished the object 

 in view. 



OUR BOOK SHELF. 



The First Technical College. By A. Humboldt Sexton. 



Pp. 188. 1894. (London : Chapman and Hall.) 

 WniiN John Anderson became Professor of Natural 

 Philosophy in the University of Glasgow, in 1786, he 

 began to give instruction in science to persons engaged ] 

 in industries. This was the beginning of technical ' 

 education, and the future of the new line of study was 

 to some extent provided for in C.lasgow by its founder 

 bci|ueathing the whole of his property " to the public 

 for the good of mankind and tlie improvement of science in 

 an institution to be denominated Anderson's University." 

 The total value of the property, however, was only about 

 /^looo, and this, as Prof Sexton remarks, was a small 

 sum wherewith to start a new university which was to 

 revolutionise the education of the country. Hut the gift 

 formed a nucleus which attracted other benefactions, 



% 



