NA TURK 



165 



THURSDAY, JUNE 19, 1879 



ELECTRIC LIGHTING 

 ntdairage Alectrigue. Par le Comte Th. du Moncel. 



(Paris: Hachette and Co., 1879.) 

 Electric Lighiing and Us Practical Application. By J. N. 



Shoolbred, M.Inst.C.E. (London: Hardwicke and 



Bogiie, 1879.) 

 The Electric Light in its Practical Application. By 



Paget Higgs, LL.D. (London : Spon, 1879.) 



THE little work, which now appears amongst the 

 numerous volumes of the " Biblioth^que des Mer- 

 veilles," though containing much more of real information 

 than many of the sketchy works of that popular series, is 

 somewhat disappointing. Like the other writings which 

 the Comte du Moncel has given to the world, it displays 

 a remarkable amount of industrious compilation, but the 

 arrangement of the matter collected is somewhat cum- 

 brous. A far superior book to his recent work on the 

 Telephone, it is nevertheless marred by the same occa- 

 sional confusion of thought exhibited in that work. 

 It contains, however, in a small compass, a good deal 

 of useful information, and enough serious reading to make 

 it pass as a scientific book. 



After fifty pages of generalities the author settles down 

 to discuss the different systems of magneto-electric 

 machines and their comparative efficiency. Next comes 

 a chapter on " organes excitateurs de la lumifere elec- 

 trique," which we discover to include carbons of various 

 manufacturers, and materials for lighting by incan- 

 descence. Then follow three chapters on regulators, 

 incandescent lamps, and electric candles; after that a 

 ristimi of the cost of electric lighting ; and finally a 

 capital chapter on its numerous applications. 



With regard to magneto-electric and dynamo-electric 

 machines, great pains have evidently been taken to give 

 a fair account of most of the systems of importance. In 

 this respect the present work contrasts very favourably 

 with that of M. Fontaine, in which such a disproportionate 

 amount of space is allotted to the Gramme machines. 

 Beginning with the early machines of Nollet, Wilde, 

 Holmes, and Ladd, the successive inventions of Gramme, 

 Siemens, de Meritens, Wallace, Brush, and Lontin are 

 carefully explained, excellent woodcuts of most of these 

 being appended. The "distributing" machines of 

 Lontin, Gramme, and Jablochkoff are also noticed. We 

 take exception to the statement that the Wallace- Farmer 

 machine is merely an enlarged copy of those of Wilde and 

 Lontin. It differs essentially from the former, and in point 

 of date was earlier in the field than the latter. If there 

 be one machine more than another that it does resemble, 

 it is the machine of M. Alfred Niaudet, of which M. du 

 Moncel makes no mention. On the very important ques- 

 tion of the relative efficiency of the various systems, M. 

 du Moncel has nothing to say that is new, but simply 

 reproduces the tabular results published by the authorities 

 of Trinity House and by the Committee of the Franklin 

 Institute. His treatment of the question of the cost of 

 electric lighting is even less satisfactory, the figures 

 obtained as the result of the most recent experiments 

 Vol. XX.— No. 503 



on a large scale in Paris and London being entirely 

 omitted. 



In treating of Regulators the author employs a classifi- 

 cation deserving of attention. They are divided into six 

 categories, viz. : (i) Regulators founded on the attraction 

 of solenoids, as those of Archereau, Gaiffe, Jaspar, and 

 Brush; (2) those depending on movements worked by 

 electromagnets, as the lamps of Duboscq, Foucault, 

 Serrin, Siemens, and Rapieff; (3) those with large cir- 

 cular carbons, as the regulators of Wright and Reynier ; 

 (4) those depending on hydrostatic reaction, as Way's 

 mercurial lamp ; (5) those depending on the reaction of 

 the current itself, producing mutual repulsion between the 

 carbon poles ; and (6), lastly, those with fixed carbons, 

 such as the electric candle of Jablochkoff. Lamps on the 

 principle of incandescence so-called are treated of under 

 a different head. The plate-lamp devised by Wallace is 

 not mentioned. The following account of the process of 

 manufacture of the Jablochkoff candles is new, and will 

 be read with interest : — 



"The manufacture of these candles carried on on a 

 large scale at the Avenue de ViUiers, where six or eight 

 thousand a day are made, is really very interesting, 

 especially the manner in which the insulating portions 

 are fashioned. Upon a marble table slightly oiled is 

 spread, by means of a moulding instrument made of a 

 toothed strip of zinc fixed so as to slide in a suitable 

 frame, a thin layer of plaster of Paris mingled with 

 sulphate of baryta, and mixed so as not to set rapidly. 

 This plaster is placed in front of the moulding instru- 

 ment, which is then moved over the marble slab in such 

 a way as to form grooves and ridges about two metres 

 long. After the moulding tool has been passed back- 

 wards and forwards several times, a fresh quantity of 

 plaster is placed in front of the instrument, thus in- 

 creasing the thickness of the ridges ; and at the end of 

 five or six operations of this kind the ridges have exactly 

 the thickness of the teeth of the moulding-tool, or that 

 required for the insulator. The sides of these insulating 

 strips are naturally made slightly concave to receive the 

 carbons, which are cylindrical." 



An account of the condensers employed by M. Jab- 

 lochkoff in conjunction with the alternate-current gene- 

 rators that feed a series of candles, will also be found of 

 some interest. M. du Moncel states that, without these 

 condensers, the candle which has the least resistance of 

 the four on one circuit absorbs so much of the current, 

 that the other three are put out. 



We have noticed, in perusing the work, a number of 

 minor blemishes, which, should the book reach a second 

 edition, might with advantage be removed. Thus we are 

 told on p. 13, that Humfry-Davy [sic), in 1813, made the 

 first experiments on the production of the voltaic arc, 

 and that this discovery was " completed " by Foucault by 

 the substitution of gas carbon for wood charcoal. If we 

 remember rightly. Sir Humphry Davy's experiment in 

 the Royal Institution, as recounted in the Philosophical 

 Transactions for 1809, were made in 1808. Foucault' s 

 suggestion came in 1844. 



What are we to understand by the following statement 

 on p. 6 ? — " The tension of a current, which is often now- 

 adays confounded (these italics are ours) with ihepotential, 

 is the property of the electric fluid which gives in, ^(jnie 



sort the impulse of tlie electric movement " This 



statement may be put by the side of another on p. 15, 

 that it is possible "to augment the intensity of a gene- 



I 



