June lo, iSSo] 



NATURE 



135 



It may interest such of cur readers as are conversant with the 

 German language to know that in tlie course of the present 

 month Dr. Ernst von Hesse Wartegg will deliver a lecture at the 

 German Athenxum (93, Mortimer Street, W.), entitled "Das 

 Leben der Beduinen." The secretary of the institution will 

 famish all particulars regarding exact date and admission to the 

 lecture on application by letter. 



After the example of the German and Austrian Alpine Clubs, 

 a Bohemian Mountain Club is now in course of formation. 



The authors of Sweden and Finnland have edited a festive 

 paper, " Nordostpassagen," in honour of Prof Nordenskjold's 

 return, which deserves high commendation, both with regard to 

 text and illustrations. It is published by C. E. Fritze, of 

 Stockholm. 



In a letter from M. Berlioux, read at the Taris Academy of 

 Sciences on May 31, the ivriter attempts to prove from the last 

 expedition of Dr. l\ohlfs in the Eastern Sahara the marvellous 

 correctness of Ptolemy's Tables. 



It is stated that Col. Gordon, who has resigned hii post on 

 the staff of Lord Ripon, is to proceed to Zanzibar to join the 

 Belgian African exploring expedition. 



The question of the speedy completion of the Ordnance 

 Survey came up in the House of Commons last Friday, when 

 there was an almo. t unanimous consensus of opinion that Govern- 

 ment ought at cnce to advance as much money as was necessary 

 to complete the work. The reply of Mr. Adam and Mr. Glad- 

 stone was virtually a iion fossumtis. It was not so much the 

 difficulty of advancing the money as of obtaining the necessary 

 amount of skilled labour to carry on the work under pressure. 

 At the present rate the survey cannot be completed for eighteen 

 years. 



DR. 



SIEMENS' NEU'EST ELECTRICAL 

 RESULTS 



A PAPER was read on Thursday last before the Society of 

 ^ Telegraph Engineers by Dr. Siemens, F.R.S., upon 

 "Recent Applications of the Dynamo-Electric Current to Metal- 

 lurgy, Horticulture, and the Transmission of Power." The author 

 first referred to the inaugural address which he had given before 

 the Society on his election to his second presidency, wherein he 

 drew- attention to the applicability of the dynamo-electric current 

 to purposes beyond the range of what electricity had theretofore 

 been employed in effecting. On the present occasion he corro- 

 borated his statements by a reference to recent experimental 

 results of his own. 



The first part of the paper had reference to an electric furnace. 

 This furnace comsists of any ordinary crucible of plumbago or 

 other highly refractory material, which is placed in a metallic 

 jacket or outer casing, the intervening space being filled up with 

 pounded cliarcoal or other bad conductor of heat. A hole is 

 pierced through the bottom of the crucible for the admission of a 

 rod of iron, platinum, or dense carbon, such as is used in electric 

 illumination. The cover of the crucible is also pierced for the 

 reception of the negative electrode, by preference a cylinder of 

 compres ed carbon of comparatively large dimen-ions. At the 

 enJ of a beam supported at its centre is suspended the negative 

 electrode by means of a strip of copper, or other good conductor 

 of electricity, the other end of the beam being attached to a hollow 

 cylinder of iron free to move vertically within a solenoid coil of 

 wire, presenting a total resistance of about fifty units or ohms. 

 By means of a sliding weight the preponderance of weight of 

 the beam in the direction of the solenoid can be varied so as to 

 balance the magnetic force w ith w hich the hollow iron cylinder 

 is drawn into the coil. One end of the solenoid coil is connected 

 with the positive, and the other w ith the negative pole of the 

 electric arc, and, being a coil of high resistance, its attractive 

 force on the iron cylinder is proportional to the electromotive 

 force between the two electrodes, or, in other words, to the 

 electrical resistance of the arc itself. 



An automatic adjustment of the arc thus arises of great im- 

 portance to the attainment of advantageous results in the process 

 of electric fusion ; w ithout it the resistance of the arc wotild 

 rapidly diminish with increase of temperature of the heated 

 atmosphere within the crucible, and heat would be developed in 

 the dynamo-electric machine to the prejudice of the electric 

 furnace. The sudden sinking or change in electrical resistance 

 of the material undergoing fusion would, on the other hand. 



cause sudden increase in the resistance of the arc, with a like- 

 lihood of its extinction, if such self-adjusting action did not 

 take place. 



Another important element of success in electric fusion consists 

 in constituting the material to be fused the positive pole of the 

 electric arc. It is well known that it is at the positive pole that 

 the heat is principally developed, and fusion of the material con- 

 stituting the positive pole takes jjlace even before the crucible 

 itself is heated up to the same degree. This principle of action 

 is of course a]iplicable only to the melting of metals and other 

 electrical conductors, such as metallic oxides, which constitute 

 the materials generally operated upon in metallurgical processes. 

 In operating upon non-conductive earth or upon gases it becomes 

 necessary to provide a non destructible positive pole, such as 

 platinum or iridium, which may, however, undergo fusion and 

 form a little pool at the bottom of the crucible. 



In this electrical furnace sc me time, of course, is occupied to 

 bring the temperature of the crucible itself up to a considerable 

 degrte, but it is surprising liow rapidly an accumulation of heat 

 takes place. In working with the modified medium-sized dynamo 

 machine, capable of producing thirty-six w ebers of current with 

 an expenditure of four horse-power, 'and which, if used for 

 illuminating purposes, produces a light equal to 6,000 candles, I 

 find that a crucible of about twenty centimetres in depth, im- 

 mersed in a non-conductive material, is raised up to a white heat 

 in less than half an hour, and the fusion of one kilogram of steel 

 is effected within, say, another half-hour, successive fusions being 

 eft'ected in somewhat diminishing intei-vals of time. It is quite 

 feasible to carry on this process upon a still larger scale by 

 increasing the power of the dynamo -electric machine and the 

 size of the crucibles. 



It was shown by means of a calculation that this furnace 

 utilises J of the horse-power actually expended, and as the 

 efficiency of a good steam-engine is I, that of the electric furnace 

 is 1 X 1 = tV- Now as it takes theoretically 450 heat units to 

 melt 1 lb. of steel, there will be required actually 450 X 15 — 

 6,750 units in working with the electric furnace, or about the 

 heat-energy residing in a pound of ordinary coal. To melt a 

 ton of steel in crucibles in the ordinary air-furnace as practised 

 at Sheffield, 2i to 3 tons of best Durham coke are consumed. 

 A ton cf coal is consumed per ton of steel produced if the re- 

 generative gas furnace is used for heating the crucibles, whilst to 

 produce steel in large quantities on the open hearth of this furnace 

 about 12 cwt. of coal per ton of steel suffice. The electric 

 furnace may therefore be considered as economically superior to 

 the ordinary air-furnace, and, barring some incidental losses not 

 included in the calculation, is nearly equal to the regenerative 

 gas-furnace as far as economy of fuel is concerned. In favour 

 of the elect] ic furnace is an almost unlimited temperature, easy 

 application, a neutral atmosphere within the crucible, and the 

 circumstance that the heat within the crucible is greater than that 

 external to it, whereas in ordinary fusion the temperature of the 

 crucible is higher than that of metal within. 



On the occasion of reading the paper a pcund of broken files 

 was melted in a cold crucible by means of a current of 72 

 webers in fifteen minutes, and cast in a liquid state, a second 

 casting being eft'ected in ei^ht minutes. These and other brilliant 

 successes of the new apparatus were hailed with ringing cheers. 



In the second portion of the paper, referring to electro- 

 horticultiu-e, the author explained the experiments by means- 

 of which he has come to the omclusion that electric light 

 produces the colouring matter chlorophyll in the leaves of 

 plants, that it aids their growth, counteracts the effects of night 

 frosts, and promotes the setting and ripening of fruit in the 

 open air. It appears, further, that, at all events for certain 

 short periods, plants do not require a period of rest during the 

 twenty-four hours, but make increased and vigorous progress if 

 subjected during daytime to sunlight and to electric light at night. 

 These observations on combined sun and electric light agree with 

 those made by Dr. Schiibeler of Christiania, who found as the 

 result of continued experiment in the north of Europe, during an 

 Arctic summer, that plants, when thus continuously growing, 

 develop more brilliant flowers and larger and more aromatic 

 fruit than when under the alternating influence of light .and dark- 

 ness. As Dr. Siemens has found that under the influence of 

 electric light plants can sustain increased stove heat without 

 collapsing, he is of opinion that forcing may be effected in an 

 electric stove or enclosure containing an electric light, and that 

 horticulturists may thus grow fruit of excellent aroma and flowers 

 of great brilliancy w ithout immediate solar aid. To test what 



