NA rURE 



26s 



H EI N RICH HERTZ. 



THE last day of 1893 witnessed the tragic death 

 of Prof. Milnes Marshall on Scawfell : on the 

 New Year's Day Prof. Heinrich R. Hertz passed away, 

 and his death will be even more severely felt in 

 many circles and more widely mourned. For some time 

 he had not been in good health. Last winter a severe 

 illness prevented him from discharging his professional 

 duties : for some weeks he was confined to his bed, and 

 fears were entertained that he might not recover. During 

 the summer-semester he got better and was again able to 

 lecture ; a casual observer would scarcely have thought 

 that there was anything wrong with him. He was in 

 excellent spirits, and his friends hoped that the vacation 

 would com.plete his restoration to health and strength. 

 But with the returning winter there came a relapse. A 

 chronic, and painful, disease of the nose spread to the 

 neighbouring Highmore's cavity and gradually led to 

 blood-poisoning. He was conscious to the last, and 

 must have been aware that recovery was hopeless ; but 

 he bore his sufferings with the greatest patience and 

 fo: titude. 



Hertz is best known through his magnificent series of 

 reicarches on electric waves. He was led, somewhat 

 indirectly, to these by a problem proposed in 1879 by the 

 Berlin Academy of Sciences, viz. to establish experi- 

 mentally a relation between electromagnetic forces and 

 the dielectric polarisation of insulators. At this time 

 Hertz was assistant in the Berlin Physical Institute, and 

 his attention was directed to the problem by Prof, von 

 Helmholtz. The oscillationsof Leyden jars and of open 

 induction-coils first attracted his attention ; but he 

 reluctantly came to the conclusion that any decided 

 effect could scarcely be hoped for. Yet he kept the 

 matter in mind ; and certain experiments made a few 

 years later — when he had become Professor of Physics at 

 the Karlsruhe Polytechnic — led him to the production 

 and examination of electric oscillations of very short 

 period (about a hundred-millionth of a second). The 

 paper "On very Rapid Electric Oscillations," which was 

 published in 1887, was the first of a splendid series of 

 researches which appeared in Wiedemantis Atmalen 

 between the years 1887 and 1890, and in which he 

 showed, with ample experimental proof and illustration, 

 that electromagnetic actions are propagated with finite 

 velocity through space. These twelve epoch-making 

 papers were afterwards republished — with an introductory 

 chapter of singular interest and value, and a reprint of 

 some observations on electric discharges made by von 

 Bezold in 1870— under the title Utitersuchungen iiber 

 die Ausbreitung der elektrischen Kraft. (An English 

 translation of this book, with a preface by Lord Kelvin, 

 has just been published.) 



As early as 18S3, Prof. G. F. Fitzgerald read a paper at 

 the Southport meeting of the British Association, " On 

 the Energy Lost by Radiation from Alternating Currents," 

 and at the same meeting pointed out that electromag- 

 netic waves of as little as two metres wave-length, or even 

 less, could be obtained by discharging an accumulator 

 through a small resistance. In a paper on " The Theory 

 of Lightning-conductors," published in the Phil. Mag. 

 in August, 1888, Dr. O. J. Lodge suggested that waves of 

 20 or 30 cm. length from a small condenser might be 

 concentrated upon some sensitive detector ; that shorter 

 waves still might be obtained by discarding the condenser 

 and simply producing oscillations in a sphere or cylinder 

 by giving it a succession of sparks ; and that light- 

 waves in all probability were only smaller editions of 

 these. It was reserved for Hertz to discover, and apply 

 with marvellous ingenuity, the necessary " detector," a 



NO. 1264, VOL. 49] 



resonating circuit with an air-gap, the resistance of which 

 is broken down by well-timed impulses so that visible 

 sparks are produced. It was only after this paper was 

 written that Dr. Lodge read how Hertz had succeeded in 

 detecting electromagnetic waves in free space, in inves- 

 tigating their reflection, and measuring their velocity ; 

 and at the end of a postcript to the same paper anno'mc- 

 ing the news there occurs the sentence : " The whole 

 subject of electrical radiation seems working itself out 

 splendidly." How amply this statement has been sub- 

 stantiated we now know.i 



When his earlier papers on electric oscillations were 

 written, Hertz was not aware of von Bezold's observa- 

 tions, nor that the subject was engaging the attention of 

 physicists in Great Britain. He readily and gracefully 

 acknowledged the value of the work done by others ; and 

 it is equally pleasant to recollect that, when he had 

 attained the goal towards which others were striving, 

 Profs. Oliver Lodge and Fitzgerald were foremost in an- 

 nouncing his success and in preparing the English- 

 speaking world to appreciate the importance of the 

 discoveries which he had made and might yet be expected 

 to make. None, we may be sure, more deeply mourn 

 the death of this brilliant investigator — in his thirty- 

 seventh year — than those who have travelled along the 

 same path, and can fully appreciate the value of his 

 work. 



It would perhaps be an exaggeration to say that the 

 news of Hertz's discoveries (with his consequent appoint- 

 ment as successor to Clausius in the chair of Physics at 

 Bonn) reached Germany by way of England. But at the 

 time when these researches were undertaken Maxwell's 

 theory does not appear to have been very widely known 

 in Germany, and it is certain that its importance was not 

 generally recognised. It seems that Hertz himself did not 

 at first appreciate how rich and suggestive it was. But 

 when he showed how worthily he could follow in the foot- 

 steps of Faraday and Maxwell, his work received instant 

 and ample recognition in England. In December, 1890, he 

 came over to England to receive the Rumford medal, 

 which was conferred upon him by the Royal Society for 

 his researches on electromagnetic radiation. He was 

 delighted with the warm welcome which he received, 

 and often spoke of it with obvious pleasure. 



It might be thought that a world-wide reputation so 

 rapidly attained would produce in a young man some 

 feeling of elation and pride, and in his colleagues some- 

 what of envy. But Hertz's modesty was proof against 

 the one, and his unvarying courtesy and ready recog- 

 nition of the merits of his co-workers made the other 

 well-nigh impossible. He was a most lovable man, and 

 was never happier than in giving pleasure to others. He 

 was always ready to show hospitality to scientific men 

 from England and America who came to Bonn. Even 

 under the restraint of a foreign tongue (he spoke and 

 wrote English with considerable fluency) his conversa- 

 tion was charming. When entertaining friends he kept 

 the learned professor well in the background, and his one 

 desire was to make every guest feel at ease and happy. 

 Many of his students will remember with pleasure certain 

 trips to the Siebengeberge, and delightful evenings spent 

 in his house in the Ouantius-Strasse. 



Absolutely devoid of any desire to pose before the 

 public. Hertz yet showed on occasion that he could ably 

 act as a popular exponent of experimental research. 

 After the publication of his fascinating researches on 

 electric radiation — its rectilinear propagation, reflection, 

 refraction, and polarisation — he was invited to address 

 the Naturforscheiversammlung (which corresponds to 

 our British Association) at Heidelberg, in 1889. He 



Mt may not be out of place to observe here that Hertz appears to have 

 made a mistake in saying that Poincare first pointed out the error of calcu- 

 lation in his important paper " On the Finite Velocity of Propagation of 

 Electromagnetic Actions." (English edition, pp. 9, 15, 270.) It seems clear 

 that Lodge {Phil. Mas;. July, 1SS9) first drew attention to it. 



