Nov. 2 1, 1889] 



NATURE 



51 



amongst its members, and of such joint action as will 

 further the use and success of these electrical trades. 

 Hence its objects are not, exactly speaking, scientific) 

 at least in the usual sense of the word, and the inter- 

 mixture of genuine desire to exchange veritable expe- 

 rience, with a certain element of effort to push into notice 

 particular personal " interests," renders a discriminating 

 mind necessary in dealing with its Reports. At the time 

 of writing, when the work of practically providing London 

 with distributed electric current is being carried on with 

 energy in diverse directions, and the various Electric 

 Supply Companies are laying down mains and establish- 

 ing stations, this Report serves a useful purpose of 

 enabling us to judge the present state of the industry in 

 jthe country where, of all others, it has had the most 

 I unhindered development. 



In his opening address, the President, Mr. S. A. Dun- 

 can, gave some figures which are significant of the 

 immense extent to which the electric lighting business 

 has now progressed in the United States. The total 

 number of arc lights in daily use is about 220,000 ; of 

 incandescent lamps, some 2,500,000. There are approxi- 

 mately 5700 central stations and isolated plants, supply- 

 ing electric current to single buildings or groups, or 

 : Sections of towns. There are 53 electric railways in 

 Operation, and 44 in progress, on which 378 electric 

 ttram-cars travel over 294 miles of track. The total 

 papital employed and sunk in these various undertakings 

 ts probably not under fifty millions sterling. When we 

 bonsider that this is the growth of ten years, we are 

 Dound to admit, not only that this youngest of the applied 

 sciences is of vigorous growth, but that its commercial 

 aasis must be sound. The Proceedings of the Conven- 

 :ion take the form of a series of Reports on various 

 Joints of interest which are drawn up by individuals or 

 Committees, and then discussed by the whole body. 



One of the important questions which in this meeting 

 eceived consideration was that of underground con- 

 iuctors. It has been evident for a long time that arc-light 

 vires, telephone, telegraph, fire-signal, and incandescent- 

 amp wires cannot be permitted to increase without limit 

 n the form of overhead conductors. In the early days of 

 he telephone and arc light the inconvenience of overhead 

 vires did not present itself as a formidable one ; but, with 

 heir rapid growth, the dangers to life and property arising 

 rom an indiscriminate collection of electric wires strung 

 in poles or attached to roofs in large cities became ap- 

 ;nt. Hence has arisen a demand that they shall be 

 underground. 



nfortunately this is not so easy in practice as it seems. 



: distributing companies in many cases desire to avoid 



'ost of making the exchange in those cases in which 



cy are operating overhead wires. The expense of an 



uderground system of conductors is from five to ten 



•s that of aiirial lines. Moreover, the various methods 



;ested for sub-laying the conductors in streets and 



' Is have all peculiar merits and demerits. Mr. Edison, 



is well known, places the copper conductors in steel 



cs, insulating them with a bituminous compound, and 



f^ys these like gas-pipes in the streets. This system has 



|een operated for years in New York, Milan, Boston^ 



nd Chicago, with a high degree of success. Other in- 



entors have advocated a conduit system ; others, again. 



the use of bare copper conductors insulated in a subway. 

 It is thus seen that the necessary experience for satis- 

 factorily laying down underground systems of conductors 

 for the conveyance of large electric currents is only slowly 

 being collected. 



The city of Chicago has one of the most completely 

 developed systems ofunderground conductors for arc-light 

 wires. There are some seventy-eight miles of under- 

 ground cable conveying currents under a pressure of 

 iooo~i8oo volts. The members of the Convention not 

 unnaturally exhibited considerable differences of opinion 

 on this question of underground conductor systems. 

 A Committee appointed for the purpose had issued a 

 circular to about 1066 managers of central stations and 

 lighting systems and others, with the object of eliciting 

 their opinions on the subject of underground conductors. 

 Out of this number 130 returned very full answers to the 

 various questions, and the diversity of opinion seems 

 very great. It is difficult, however, to believe that the 

 process of collecting information was that which would 

 lead to the best results, and although the various views 

 put forward in the discussion on the Report are interest- 

 ing, they do not indicate a solidarity of opinion on any 

 one point. It is perfectly certain, however, that in 

 England electric conductors for systems of town light- 

 ing by electricity will have to be placed underground, 

 and it is also equally certain that those responsible 

 for this work will have to exercise the greatest dis- 

 cretion and take the fullest advantage of existing ex- 

 perience. The question of the fire risks of electric 

 lighting also occupied the attention of the members. In 

 the United States, as with us, the opinion based on 

 experience is that when the work of installing the electric 

 light is carried out under all known proper precautions, 

 and by the best guidance, there is greater safety in it 

 than in gas illumination, but that when these known 

 precautions are disregarded then danger ensues. Minor 

 questions, such as the disruptive discharges in lead 

 cables and fuel oil, attracted briefer attention. The im- 

 portance of such a gathering in guiding the experience of 

 those who are fostering an industry like that of electric 

 lighting, in Avhich invention advances by leaps and 

 bounds, is very great. We in England, thanks to the 

 revision of the Electric Lighting Act, are now entering on 

 a period of great electrical activity, and already it has 

 been found that the commercial side of electrical engin- 

 eering requires the association of those engaged in it for 

 mutual advice and joint action, and the London Chamber 

 of Commerce has now an active Electrical Section which 

 fulfils to some extent the functions of the National Elec- 

 tric Light Association in America. 



J. A. F. 



DIANTHUS. 



Enwneratio Specierian Varietatuviqiie Generis Dianthia. 

 Auctore F. N. Williams, F.L.S. Pp. 23. (London: 

 West and Newman, 1889.) 



ONE of the things most wanted by species-botanists 

 at the present time is a set of monographs of a 

 number of the familiar large genera of Polypetalous 

 Dicotelydons. The natural orders of PolypetaL-e were 



