February 1 1, 1892] 



NA TURE 



345 



" The colour was estimated by Mr. Fowler as reddish- 

 yellow, and by Mr. Baxandall as i-ather purplish. My 

 own impression was that the star was reddish, with a 

 purple tinge. This was in the lo-inch achromatic. In 

 the 3-foot reflector it was certainly less red than many 

 star of Group II. No nebulosity was observed either in 

 the 3-foot or the lo-inch refractor, nor does any appear in 

 a photograph of the region taken by a 3i-inch Dallmeyer 

 lens with three hours' exposure. It should be stated 

 that the camera was carried by the photographic tele- 

 scope, the clock of which had had its normal rate pur- 

 posely changed to give breadth to the spectrum. 



" The photographs were taken and reduced by Messrs. 

 Fowler and Baxandall. The eye-observations and com- 

 parisons were made by Mr. Fowler." 



The nights of Thursday, Friday, and Saturday were 

 hopelessly bad, but on Sunday night the weather cleared, 

 and more photographs were taken at South Kensington, 

 an account of which, we believe, has been communicated 

 to the Royal Society. Observations of the Nova are there- 

 fore well in hand, and there is no doubt that a comparison 

 of the photographic plates obtained in December and 

 February will provide us with much minute information 

 regarding the behaviour of our new visitor. 



The remark in Mr. Lockyer's communication to the 

 Royal Society, that the spectrum of the star contained 

 nearly all the lines visible in the stars in Cygnus, is one 

 of considerable interest and importance, because, if it be 

 confirmed by subsequent observations, it will show that 

 these stars in Cygnus cannot be stars in the true sense — 

 that is, bodies like our sun. This seems pretty evident 

 from the fact that their spectroscopic phenomena can be 

 reproduced by another body which suddenly appears, and 

 probably will rapidly become invisible. The idea that 

 any of these bodies are " worlds on fire," as was once 

 thought, need now no longer be discussed. 



MR. TESLA'S LECTURES ON ALTERNATE 

 CUNRENTS OF HIGH POTENTIAL AND 

 FREQUENCY. 

 T T is not often that the outward and visible signs of a 

 ^ great scientific success are so prominent as they 

 were last week at the Royal Institution. The reports 

 which have reached this country of the work of Mr. 

 Nikola Tesla have made his name known to those who 

 are watching or aiding the progress of electrical science. 

 He was recently invited by the Institute of Electrical 

 Engineers to lecture before it, and the interest which his 

 coming excited spread in widening circles as the day on 

 which he was to exhibit his experiments drew near. 



It was evident that the ordinary meeting-room of the 

 Institute would be too small, and the Managers of the 

 Royal Institution placed their theatre at its disposal. 

 Members of the Royal Institution, were, however, 

 anxious to hear and see for themselves ; and finally Mr. 

 Tesla consented to lecture on two consecutive nights to 

 the Institute and the Institution respectively. 



On both occasions the room was full ; on the first 

 it was overflowing. Gathered round the lecture table 

 was a crowd of those whose business it is, either as 

 theorists or as practical men, to keep abreast of the 

 wave of scientific advance ; but as the youthful lecturer 

 — who looks even younger than his years— with a 

 modesty and charm of manner which were altogether 

 irresistible, showed wonder after wonder, the interest of 

 this critical audience deepened into enthusiasm. The 

 speaker's broken English and imperfect explanations 

 did not detract from his success. His marvellous skill 

 as an experimentalist was evident and unmistakable, 

 and his hearers left the room convinced, not only that 

 another step forward has been taken, but also that in 

 NO. I 163, VOL. 45] 



Mr. Tesla we have a scientific explorer, who, if health 

 and life be granted him, will travel fast and far. 



Briefly, Mr. Tesla has done much to attain the con- 

 tinuous stream of electrical oscillations which Prof. Fitz- 

 gerald, at a recent meeting; of the Physical Society, com- 

 pared to a continuous whistle. The oscillations which 

 Hertz studied die out almost instantaneously. Could they 

 be maintained, a practically new weapon would be placed 

 in our hands. Tesla does not, indeed, maintain them, 

 but he renews them many times per second, and the 

 results are marvellous. 



Though the potential is enormous, the electrode of the 

 apparatus can be safely handled. If a person in conduct- 

 ing communication with it touches a vacuum bulb or tube 

 it glows, and if the tube is brought near to others it sets 

 them a-glowing too. No return is needed, the current is 

 completed through surrounding space. The phospho- 

 rescent materials in some of the beautiful tubes lent by 

 Mr. Crookes shone brightly when one electrode only was 

 connected with the coil. If the terminal is surrounded 

 by an aluminium tube, the glow is notably increased. 

 The experiment of making a vacuum-tube luminous by 

 simply holding it in an oscillating field was successfully 

 performed, and the lecturer himself received with impunity 

 a crackling discharge, some six or eight inches in length, 

 by holding his hand at that distance from the terminal of 

 his coil. 



All these things are not merely wonders. Mr. Tesla is 

 working with an object. He is one of those who hold 

 that a phosphorescent glow is the light of the future. 

 He hints at artificial aurorae spreading from the summits 

 of towers of hitherto undreamt-of height, and he has at 

 all events got as far as producing in air at atmospheric 

 pressure a glowing plane bounded by two rings about a 

 foot and thirty inches in diameter respectively. Whether 

 his visions will all be realized may be doubtful. There is 

 is no doubt that they are guiding him aright. As Lord 

 Rayleigh said in moving the vote of thanks, a door has 

 been opened into a new region of inquiry, into which 

 Mr. Crookes and Mr. Tesla have entered almost alone. 



Those who some fifteen months ago heard Prof. 

 Hertz acknowledge in terms of genuine emotion that he 

 had built upon a foundation laid by Englishmen, that 

 Englishmen had first recognized the importance of his 

 work, and that from England its first reward had come, 

 must have listened with pleasure when the part that this 

 country has taken in the development of electrical 

 science was referred to in a like appreciative tone 

 by Mr. Tesla. It is not indeed that the achievements of 

 our great electricians are bettered or rendered more im- 

 portant by acknowledgment, but it is pleasant to note 

 how cosmopolitan science is becoming, and that among 

 scientific workers the feeling of fellowship is overcoming 

 that of rivalry. For the rest we can only congratulate 

 Mr. Tesla alike upon his work and his reception, and 

 the scientific world on the exhibition of a number of 

 beautiful experiments which will afford food for useful 

 reflection to theorist and experimenter alike. 



A. W. R. 



The announcement of Mr. Nikola Tesla's lecture 

 to the Institution of Electrical Engineers excited wide- 

 spread interest among all in the least degree interested 

 in electrical science. The succession of almost marvellous 

 experiments in which in great measure it consisted must 

 have gone far beyond the anticipations of the most san- 

 guine of those of the audience who had had no previous 

 account of the nature and results of his work. It is not 

 too much to say that the Royal Institution lectures mark 

 a distinct epoch in the progress of theoretical and applied 

 electricity. While, on the one hand, the experiments 

 which the lecturer showed seemed to point to a possible 

 revolution of our methods of electric lighting, on the 

 other hand they must have suggested, if not for the first 



