742 



NA TURE 



[December 2, 1922 



optical reflection, even of the metallic type, from some 

 crystals had been known and understood in its main 

 features for a long time. 1 It was left for Rubens to 

 develop it into what amounted to a new kind of spec- 

 trum analysis for invisible rays far down in the infra- 

 red, by sifting the radiation by successive reflections. 

 Bv this means he discovered and isolated precise narrow 

 bands of dark radiation (Reststrahlen) very remote 

 from the visible spectrum : just what was most needed 

 at that time for the wider verification and consolida- 

 tion of ideas regarding the general laws of radiation. 

 In collaboration with Rubens in these investigations 

 his friend E. F. Nichols first made his mark, soon to be 

 followed up at home in America. 



In later years by use of the Reststrahlen he was able to 

 discover that in metals the defect from perfect reflection, 

 for radiation of great wave-length, depended on their 

 conductances alone. This was readily intelligible in a 

 general way : for the square of the complex index of 

 refraction for rays of frequency pJ2ir is of the form 

 K- 47tc 2 P' 1 <tl, and as both terms of it are found to be 

 effective in metals for ordinary light, the second term, 

 involving p' 1 and the specific conductance <r, must 

 predominate far in the infra-red. But the entirely 

 unexpected feature was that the agreement was so close 

 that optical observations by themselves could give a 

 good value for the ordinary conductance o- of a metal 

 for continuous currents. In other words, the response 

 to electric force in metals is so prompt that the mechan- 

 ism of conductance becomes completely established 

 within the fraction io" 13 of a second of time, thus 

 giving an essential datum for the understanding of the 

 process of transfer of electrons in metallic bodies. 



The decisive completeness of this incidental verifica- 

 tion of the Maxwellian scheme of radiation naturally 

 attracted general attention, in its contrast with the long 

 years that elapsed in the early time before the cause of 

 the imperfect correspondence of the refractive index 

 with v 'K for transparent media was fully appreciated. 



One was struck with the ease and simplicity of 

 Rubens' modes of thought. The problems which he 

 wished to attack came naturally to him, without an)' 

 incrustation of theoretical complexities. x Like Faraday 

 and many another experimenter, he was an example 

 of how far simple physical intuition could lead. The 

 directness and cordiality of his personal qualities must 

 have won and retained the regard of all who knew him. 

 Joseph Larmor. 



Lieut. -Col. G. L. Tupman. 

 Lieut. -Col. George L. Tupman, who died at 

 Harrow on November 4 at an advanced age, was for 

 many years a devoted amateur astronomer. He was 

 elected a Fellow of the Royal Astronomical Society in 

 1863, being one of the oldest Fellows at the time of his 

 death. He was on its council from 1873 to 1880, and 

 set retary from 1884 to 1889. His earliest astronomical 

 work was on meteor radiants ; he made numerous 

 observations of meteors while on service in the Mediter- 

 ranean, 1869-1871, and published a catalogue of radiants 

 in Mon. Not, R.A.S., vol. s?>- Tupman observed the 

 transits of Venus in 1874 and E882 from Honolulu and 

 New Zealand respectively, lie worked for some time 



1 Cf. ex. gr. Stores in discourses at the Royal Institution and to the 

 Chemical Society, as early as 1864 : "Math, and Phys. Papers," vol. iv. 

 pp. 244, 261. 



NO. 2770, VOL. I IO] 



.it Greenwich Observatory as a volunteer, both in pre- 

 paration for the transits and in their subsequent dis- 

 cussion ; his preliminary result from a discussion of the 

 1874 transit, 8"-8i3, is very near the value now accepted. 

 Since many of the stations were dependent on lunar 

 observations for longitude, he studied carefully the 

 errors of the lunar ephemeris from the results of all the 

 leading observatories. 



Tupman had a well-equipped observatory at Harrow, 

 with two equatorials, reflector and refractor, and a 

 transit circle. He made many meridian observations 

 of stars, also occultations (especially during the lunar 

 eclipses of 1884, 1888, 1895 for the determination of 

 the moon's diameter), comets, transit of Mercury, etc.; 

 he also frequently invited other astronomers to use 

 his instruments. A. C. D. Crommelin. 



II. J. Powell. 



By the death of Harry J. Powell, on November 26, 

 at the age of sixty-nine years, the country has lost one 

 of the earliest pioneers in the scientific manufacture 

 of glass. For some years he lived in the works at 

 Whitefriars, and during this time, and for many years 

 afterwards, he superintended personally the weighing 

 out and mixing of the material for the next week's 

 batch of glass. For forty-five years he was making 

 experiments with the object of improving the quality 

 of the flint glass made at Whitefriars, and attaining 

 perfection of colour in the glasses. These have led to 

 the magnificent results seen in the windows of the 

 cathedrals of Salisbury, Liverpool, and New York, and 

 in those of many churches in this country and abroad. 

 He not only improved the nature and colour of the 

 glass, but he was a designer of the first rank. Few of 

 the art museums of this country are without specimens 

 of His artistic skill. 



Mr. Powell was well known to most scientific men, 

 and was always ready to put his knowledge and 

 technical skill at their disposal. The vacuum flask, 

 the idea of which was conceived by Sir James Dewar, 

 was made first by him, and it was to his experiments 

 that the success of Sir William Crookes's cerium glass, 

 lor rutting off the ultra-violet and heat rays, was 

 mainly due. At the outbreak of war, foreseeing the 

 shortage of glass for chemical purposes, he worked nut, 

 in conjunction with his son-in-law, a soda-lime glass 

 with very great resistance to changes of temperature and 

 action of water. This glass was used by the Admiralty 

 nil the construction of the horns of submarine mines. 



Mr. Powell retired from the business three years ago, 

 and devoted his time to an attempt to make generally 

 known the results of his knowledge and experience. 

 He worked up to the last, the final revision of a book, 

 "Glass-making in England," and of an article for 

 Sir Richard Glazebrook's " Dictionary of Applied 

 Physics," in which he propounded a new theory of the 

 origin of colour in glass, being completed only a few 

 days before his death. 



By the death of Dr. Herbert Langton on October 12, 

 in his seventieth year, the Museums Association loses 

 its honorary treasurer, the museum sub-committee 

 mI Brighton its chairman, and the British Ornithological 

 Union a valued member. A portrait appears in the 

 Museums Journal for November. 



