594 



NA TURE 



[Febkuaky 23, 1899 



A NEW CURRENT INTERRUPTER EOR 

 INDUCTION COILS. 



MAY I call attention to the most remarkable electro- 

 lytic current interrupter due to Dr. A. Wehnelt, of 



• Charlottenburg, which appears to me to be by far the 

 most important improvement that has been made in con- 

 nection with Ruhmkorff induction coils for many years. 

 Kroin a description in the Eleclriatl Rei'ie-v for February 

 17 we have made in this laboratory one of these appliances, 

 and tried it on a lo-inch .\pps coil. The apparatus is of 



■ extreme simplicity, consisting merely of a glass vessel 

 filled with dilute sulphuric acid, into which dip two elec- 

 trodes. One of these is a plate of lead of considerable 

 area. The other is a glass tube, through the end of which 

 protrudes a short piece of platinum wire, sealed into 



' the glass. The glass tube is open at the other end, and 

 is filled with mercury, into which is dipped one of the 

 wires from a source of continuous electric current ; in our 

 ■case the mains of the Westminster Electric -Supply Com- 

 g}any. The glass tube is inmiersed in the acid so that the 

 platinum wire is some distance below the surface, and is 

 ■within half an inch or so of the lead plate. No con- 

 denser is employed, the primary terminals of the coil 

 being directly connected to the supply mains (100 volts) 

 through the electrolytic cell, the positive current being 

 arranged to pass through the cell from the platinum wire 

 to the lead. On turning on the current a rapidly inter- 

 anittent arc is seen to take jilace in the vicinity of the 

 platinum wire, ap|)arently between the latter and the 



•dilute acid. Judging from the loud hum, the frei|uency 

 ■must be some hundreds per second. At the same 

 time, between the terminals of the secondary of 

 the coil placed some five or si.\ inches apart, a 

 perfect torrent of sparks takes place, which follow one 

 another so fast that the stream appears to be almost 



■ continuous. The effect is in fact very similar to that 

 produced with a Tesla high freciuency coil, but is much 

 more constant and much less diffuse, while the stream of 

 sparks curls about in a curious and distinctive manner, 



• emitting all the time a very loud and continuous note. 



The arrangement seems likely to have wide and im- 

 portant applications in connection with Rcintgen-rays, 

 ■wireless telegraphy, and manv other purposes. It is a 



■ distinct step towards obtaining, from continuous currents, 

 alternating currents of any desired high frequency without 

 the necessity of moving parts. A. A. C. Swinton. 



63 Victoria Street, S.W. 



NOTES. 



I.N view of the iidvancement of zoological science lo be ex- 

 i])ecte<l from researches in the South Polar Lands and Seas, the 



Council of the Zoological Society of London have agreed, on 

 ■ the part of the Society, to contribute a sum of 200/. to the 



funds of the National Antarctic ICxpedition. 



The seventh "James Korrest " lecture of the Institution of 

 •Civil Engineers will be delivered liy Prof. J. A. Ewing, K.K.S., 

 on Thursday, April 20, at eight o'clock, the subject being 

 " Magnetism." The lecture will be repeated on Kriday, April 

 21, at f<jur o'clock, for the benefit of members and their 

 friends. 



We regret to announce that Dr. William Rutherford, KR.S., 

 .professor of physiology in the University of Kdinburgh, died on 

 Tuesday morning, at sixty years of age. 



Ar the annual meeting of the Russian Ceographical Society, 



• on February 2, the following medals were awarded : — The Con- 



stantine medal lo Dr. (luslav RaiUle, the director of the Tillis 



Museum, for his forly-five years' w.irk in the study of Russia : 



NO. 1530. VOL. 59] 



the Count Ltltke medal to \. \. Pomeranlseff, for his researches 

 into the forms of the earth's geoid in the province of Fergana ; 

 the .Semonoff medal to M. Kleiber, for his investigations into 

 the periods of high water in the Volga ; the great gold medal 

 of the Section of Ethnography lo N. L. (londatti, for his three 

 years' work of exploration of the Land o( the Chuckchis ; the 

 I'rzewalski medal to L. A. Jaczewski, for his physico-geo- 

 graphical researches in Siberia ; and three small gold medals 

 to M. Tachaloff, for his instruction of travellers in astro- 

 nomical observations ; A. A. Kostkovsky, for a map of popu- 

 lation in the Kitol vilayet of Turkey ; and N. A. Zarudnyi, 

 for researches in Persia ; a number of silver medals were 

 awarded for minor works. 



The Reale Istituto Lombardt) announces in its Renduon'J 

 the award of prizes as follows : — The Cagnola prize of 2500 lire 

 and a gold medal of 500 lire has been awarded to Signor Angelo 

 Battelli and Signor Annibale Stefanini for their joint paper con- 

 taining a critical exposition of electric dissociation considered 

 principally in regard to the experimental proofs of its deductions. 

 For the Kramer prize, on an essay relating lo the use of con- 

 densers in the transmission of electric energy by alternating 

 currents and their construction for industrial purposes, two 

 competitors entered, and prizes of 2500 lire and 1500 lire respec- 

 tively have been awarded to Prof. Luigi Lombard!, of Turin, and 

 Signor Giovanni Hattista Foico, director of the electric tram- 

 ways of Leghorn. For the Fossati prize, on some physiological 

 point connected with the human encephalus, two compedtors 

 entered, and awards of 400 lire have been made to both — 

 namely Dr. Domenico Mirto, of Palermo, and Dr. Carlo 

 Martinotti, of Turin. For the Brambilla prize, given for the 

 invention or introduction of some new machine or industrial 

 process of real practical value, seven competitors entered. A 

 gold medal and 500 lire has been awarded to Fratelli Boltri, of 

 Milan, for their grain desiccators ; a similar award to Premoli 

 and Zanoncelli, of Lodi, for their preparation of Gaertnerised 

 milk, (jold medals and 200 lire have also been given to Rossi, 

 Enrico, and Co., of Milan, for their manufacture of varnishes, 

 &c. ; to Piola Alfredo, of Milan, for artists' colours; and to 

 Pizzoni Pietro, of Milan, for the manufacture of baskets. 



The prizes otfered by the Realc Istituto Lon:bardo for future 

 competition include prizes of the Institution fur 1S99 for a list 

 of unusual meterological events that have been recorded from 

 the earliest times, and for 1900 for an css.iy on collective 

 property in Italy ; two triennial medals for improvements in 

 agricultural or industrial processes in Lond)ardy ; a Cagnola 

 prize and gold medal on the subjects chosen by the Institution, 

 viz. in 1S99, for an essay on Hertz's phenomenon, or the eflect 

 of active radiation or of products of combustion on the sparking 

 distance in air, and in igoo for a critical stuily of toxin and anti- 

 toxin ; a Cagnola prize and gold medal for iSggon one of the 

 following subjects chosen by the founder : viz the cure of 

 " pellagra," the nature of miasma and contagion, the direction of 

 flying balloons, and the melhodsof preventing forgery of writings; 

 a Brambilla prize fur industrial improvements in Lombardy ; 

 Fossati prizes for 1S99 on the macro- or micro-scopical anatomy 

 of the nervous system, for 1900 on the regeneration of peripheric 

 nervous fibres in vertebrates, and for 1901 on the anatomy of 

 the encephalus of the higher animals ; a Kramer prize for an 

 essay on the transmission of heat between the steam and walls 

 of the cylinders of steam-engines ; a Secco Comneno prize for 

 1902 for a description of Italian natural deposits of phosphates ; 

 a Pizzamiglio prize for an essay on the influence of socialistic 

 doctrines on i)rivale rights ; Ciani prizes for popular Italian 

 books, a Tommasoni prize for a history of the life and works of 

 Leonardo da \inci : and a triennial Zanelli prize for some 

 improvement or discovery in pharmaceutical chemistry. 



