57o 



NA TURE 



[Oct. 12, 1882 



structed a railway at his colliery at Neath in Glamorgan- 

 shire as early as 1698, but after it had been in use for 

 eight years it was declared to be a nuisance by the grand 

 jury at Cardiff, and part of it, which crossed the highway 

 between Cardiff and Neath, was torn up and the rails cut 

 in pieces. 



Up to the beginning of the eighteenth century the air- 

 currents which ventilated the mines were induced solely 

 by natural causes. It was, however, customary to guide 

 the current into the required channels by means of 

 stoppings. As soon as the supply of air was found to be 

 inadequate a new shaft was sunk. Fire-damp was now 

 met with in considerable quantities in the deeper mines, 

 and explosions, which destroyed many lives, began to 

 take place. The first calamity of this kind on the Tyne 

 occurred in 1705, when thirty lives were lost. In 1732 

 attempts were made in the North of England to produce 

 artificial ventilation by the use of fire-lamps or furnaces, 

 and these appliances were soon afterwards introduced 

 into the collieries of the Tyne. Many disastrous ex- 

 plosions occurred during the eighteenth century and early 

 in the present one, and some remedy was loudly called 

 for. As early as 1733 flint and steel were being used for 

 lighting in the Whitehaven mines, but it appears to be 

 doubtful whether the steel-mill had then been invented. 

 It is certain, however, that it had come into existence in 

 1753; when its inventor, Spedding, was referred to under 

 the name of Prospero, in a poem in which Dr. Dalton 

 calls it — 



" That strange spark-emitting wheel 



Which, formed by Prospero's magic care, 

 Plays harmless in the sulphurous air, 

 Without a flame diffuses light, 

 And makes the grisly cavern bright." 



The steel-mill was at the best a treacherous friend, and 

 our author recounts the various incidents which led to its 

 detection as such, and its abandonment. He also traces 

 minutely the various steps which led to Sir Humphry 

 Davy's splendid invention of the safety lamp in the end 

 of the year 181 5, and he gives what appears to be an 

 impartial analysis of the claims put forward by, and on 

 behalf of, George Stephenson to be the original inventor 

 of a similar lamp at the same time. 



" The discovery which Sir Humphry Davy had made, 

 that explosion would not pass through small apertures 

 and tubes, was only a stepping-stone to still higher 

 achievements; and before the close of the year 1815 he 

 gave to the world the wire-gauze lamp. This was the 

 last, the most splendid, the crowning triumph of his 

 labours — the ' metallic tissue, permeable to light and air, 

 and impermeable to flame.'" 



We must now, however, draw our review to a close 

 without having so much as mentioned many another inte- 

 resting topic which we hoped to have touched upon — such 

 as the perseverance of Sir Robert Mansell, Vice- Admiral 

 of England, in substituting coal for charcoal in glass 

 making ; the romantic struggles of Dud Dudley, son of 

 Lord Dudley, against what seemed to be a relentless fate 

 in his partially successful endeavours to effect the same 

 change in iron making- -but we can confidently recom- 

 mend the reader to the original volume, where he will rind 

 much to interest him, much, it may be to profit him, and, 

 we are sure, not a little to amuse him. 



G ARIEL'S "ELECTRICITY" 

 Traite" Pratique d' Electricity comprenant les Applications 

 aux Sciences et a I 'Industrie. Par C. M. Gariel. (Pre- 

 mier fascicule.) 200 pp., 140 figs. (Paris: Octave 

 Doin, 1882.) 



M GARIEL, Professor of Physics at the Ecole des 

 • Ponts et Chausse"es, and better known in this 

 country as the courteous and energetic secretary of the 

 " Association Francaise," gives us in the above work the 

 first instalment of an extensive book which will not be 

 completed before next year. This first instalment is 

 introductory to the whole subject, and deals with so much 

 of elementary theory as the author deems requisite to 

 give a firm grasp on his subject. Not rejecting mathe- 

 matics, the author prefers to keep the mathematical treat- 

 ment of his subject in the background. Nevertheless, 

 he makes good use of algebraical footnotes, and by these 

 and other evidences it may be judged that a firm scien- 

 tific grasp will be maintained upon the various branches 

 too often treated in a loose and unscientific manner. 



Dismissing at the outset the notion that the work is in- 

 tended for preparing for examinations, the author chooses 

 from old and new the material that will best serve his pur- 

 pose. It is very satisfactory to find modern notions, both 

 in electrostatics and in electromagnetics, rapidly taking 

 hold of the leading electricians of France. The treatise 

 of M. Mascart first showed them how far electrostatics 

 had advanced in the hands of Green, Gauss, Faraday, 

 Thomson, Clausius, and Maxwell, beyond the achieve- 

 ments of Coulomb and of Poisson. The text-books of 

 MM. Mascart and Joubert, and of MM. Jamin and Bouty, 

 testify to the extension of this salutary influence. And 

 now in the work of M. Gariel we have evidence of the 

 same progress. For example, M. Gariel breaks free 

 from servitude to the consecrated term '■'tension" so 

 often misused as a synonym for potential, electro-motive 

 force, and we know not what ; but he uses it, not however 

 in Maxwell's sense as denoting the mechanical stress along 

 the electric lines of force, but as the electric force outside 

 a closed conductor, or as the equivalent of -4»rp. 

 The ideas of Faraday on the nature of statical induction 

 are evidently in M. Gariel's mind, though we think he 

 does not give anjthing like an adequate attention to the 

 subject of specific inductive capacity, which, though of 

 immense practical importance, is passed over almost 

 without mention. Indeed the faults of the book, if such 

 we may call them in a work of such high scientific 

 accuracy, are faults of omission rather than of commis- 

 sion. The contact-theory of voltaic action is very slightly 

 sketched on p. 107; and on pp. 11 2-1 15 there is a discussion 

 of the phenomenon of the variable state (i.e. of the gradual 

 rise and fall in the strength of currents at making and 

 breaking circuit), in which all allusion to the self-induction 

 of the circuit is omitted, and which would probably lead 

 a reader to draw the conclusion that the reason why the 

 current did not at ence attain its full strength was on 

 account of bad conductivity of some part of the circuit. 

 The portion devoted to Ohm's law is fairly complete ; but 

 we think the custom of bringing all resistances to a 

 " reduced length" in the antiquated fashion of Pouillet is 

 better honoured in the breach than in the observance. 

 Amongst the newer topics introduced, and not often 



