IS2 



NA TURE 



[June u, 1894 



The exhibition of physical apparatus at Paris com- 

 prised numerous ingenious instruments, but there was no 

 attempt at arranging educational sets. Lord Kelvin's 

 voltmeters and ammeters were shown, and various in- 

 struments for measuring electric energy and resistance. 

 A binocular photometer attracted some attention, and 

 also a new kind of ophthalometer and a monochromato- 

 scope. M. V. Chabaud showed a form of electrometer 

 devised by M. Lippmann, several pieces of apparatus 

 made from dielectrine, tolueine thermometers for the 

 measurement of low temperatures, V'illard manometers, 

 V'arenne's apparatus for fractional distillation, and 

 Bichat's hygrometers. M. J. Carpentier's exhibit in- 

 cluded mica condensors, and an instrument invented by 

 General Sebert for determining the rapidity of photo- 

 graphic plates. M. J. Richard showed a meteorograph 

 constructed for the observatory on Mont Hlanc, an 

 electric anemometer, Favc sounding-line, and numerous 

 recording voltmeters and ammeters. His exhibit also 

 comprised, among other things, several of Bonetti's 

 electrical machines, Berlemont's mercury pump, and 

 various sterilisers. The photographs of interference 

 fringes obtained by M. Meslin call for special mention, 

 and also a pendulum devised by Captain Colson for 

 measuring short exposures in photography, and a theo- 

 dolite adapted to photographic work Ijy M. Kchassoux. 

 The French Photographic Society exhibited sets of 

 photographic apparatus, and M. G. Raymond some tine 

 cloud photographs. The apparatus used by M. Marey 

 for photographing objects in motion, naturally found a 

 place in the exhibition. Photographs in colours, ob- 

 tained by the Lippmann method, were seen by projection, 

 and were greatly admired. Many other results of scien- 

 tific research were shown, together with the instruments 

 by means of which they were obtained, but no useful 

 purpose would be served by enumerating them. It is 

 proposed to hold a similar exhibition next year, and if 

 instrument-makers co-operate with investigators as they 

 did in the one just closed, there can be no doubt as to 

 its value to workers in all branches of physics. 



There should be little difficulty in arranging an annual 

 exhibition of a similar kind in London. .Scientific instru- 

 ment-makers would compete with one another in showing 

 work of a high quality ; and if the exhibits were organ- 

 ised by a competent committee, the venture would be 

 successful from every point of view. R. A. G. 



AUGUST KUNDT. 



pHY.SlCAL science, which within the lapse of six 

 ■*■ years has witnessed the death of Kirchhoff, Clausius, 

 and Hertz, has suffered another severe loss ; on May 21, 

 August Kundt, who was but fifty-four years of age, sud- 

 denly died at his country place near Lubeck. 



Kundt was born at .Schwerin, on November iS, 1839, 

 and began his studies at Leipzig in i860, under llankel, 

 .Neumann, Bruhns, and others. Thence he went to 

 Berlin, where Encke, Forster, Dove, and Kummer were 

 his pnncipal teachers. He began by giving special 

 attention to astronomy, and indeed intended to devote 

 himself to that branch of science. While yet undecided, 

 however, he entered the private physical laboratory that 

 Gustav Magnus had fitted out in the I'russian capital, and 

 in which students with a decided taste for experimental 

 mvestigation were allowed to work. From the beginning 

 he displayed extraordmary experimental ability, combined 

 with rare energy in the pursuit of the work he had once 

 taken in hand, qualities which were characteristic of him 

 during his whole scientific career. He also attended the 

 physical " colloquia " which .Magnus had introduced, 

 and under the iniluence of the latter was definitely en- 

 rolled in the lists of experimental physicists. 



He graduated at Berlin in April 1864, with an invcstiga- 



NO. 1285, VOL. 50] 



tion on the depolarisation of light. The first and last of 

 the theses appended to his dissertation (dedicated to 

 Magnus^ are characteristic of the state of his mind at 

 that lime. They run as follows : — 



(i) \'ires anima" non minus metiri possumus, quam 

 vires physicas. . . . 



(4) Theoriam a CI. Fresnel de torsione planitiei polar- 

 isationis promulgatam si adoptamus, omnia ea corpora 

 qua; planitiem polarisationis torquent, sub aptis condi- 

 tionibus birefractionem demonstratura esse, negare non 

 possumus. 



He never himself followed up the psychological 

 lines of research hinted at in the first thesis ; the 

 last proposition is known to be entirely borne out by 

 modern research on circular double refraction. 



In 1S67 he became " Privatdocent " in the L'niversity 

 of Berlin, but was appointed to a professorship in the 

 Swiss federal polytechnic school at Zurich, in the follow- 

 ing year. There he remained but two years, removing to 

 Wiirzburg in i8;o, where his stay was of no longer dura- 

 tion, the then newly organised University of Strasburg 

 having called him to represent his science on a brilliant 

 stafl^of young and enterprising men, who within a few 

 years brought their "alma mater" to a high level of 

 excellence. In this work of organisation Kundt was one 

 of the most actively engaged, holding the office of rector 

 in the year 1S77, when but 38 years of age. (i"''^ apart 

 from his purely scientific reputation, this alone is suffi- 

 cient to mark his name with golden letters in the annals 

 of Strasburg University, for which he also erected an im- 

 perishable monument, the Physical Institute, well known 

 throughout the scientific world as one of the best labora- 

 tories existing. 



In iSSS, when Prof, von Helmholtz became president 

 of the " Reichsanstalt," Kundt succeeded him as pro- 

 fessor of experimental physics, and director of the Berlin 

 Physical Institute. A prolonged period of scientific 

 activity from a man of but fifty years of age with a world 

 wide reputation might still have been expected ; but these 

 hopes have proved vain. A few years ago the symptoms 

 of a disease began to appear, which could not be subduetl. 

 Kundt fought for life to the last ; and notwithstanding the 

 slow but unceasing strides his ailment made, which wouKl 

 have entirely prostrated most other men. he continued 

 his lectures and other pressing duties during the whole 

 of last winter, thus setting an example of sacrifice to the 

 cause of science even in the face of death. When, at the 

 urgent instance of his medical advisers and friends, he 

 stopped work and left Berlin, it proved of no avail ; in 

 fact, he may be said to have died as he had lived, in 

 the midst of scientific work. 



As an investigator Kundt was many-sided ; his dis- 

 coveries are so generally known, that it is hardly neces- 

 sary to describe them in detail. He first turned hi-- 

 attention to acoustics ; his start in scientific life being tin- 

 invention of the well-known " Kundt's sound tubes," 01 

 " Kundt's dust figures," which he himself and others 

 turned to account in many ditfcient ways. The application 

 of that purely acoustic method led to the determination 

 of the ratio of specific heats of mercury vapour. In col- 

 laboration with Warburg (1884), Kundt found this to be 

 5 3, as predicted by the kinetic theory for a monatomii 

 gas. lie also conducted researches on thermal con- 

 ductivity and inler-diffusion of gases or vapours and on tin 

 influence of pressure on the surface tension of liquids . 

 and developed his well-known red and yellow dust-spi.i 

 method for investigating the pyro-electnc and piezu 

 electric properties of crystals. 



But in glancing over his li(e-work as it now lies before 

 us, it appears as if the palm ought to be assigned to his 

 optical and magneto-optic discoveries, lie began with .1 

 brilliant series of papers on anomalous dispersion, whii li 

 placed this important subject on a sound footing. He de 

 scribed the doubly refractive properties of vibrating solids. 



