Sept. lo, 1874] 



NATURE 



377 



Fraunhofer, at the beginning of this century, pointed 

 out the coincidence of place in the spectrum between 

 certain dark lines which he saw in the spectrum of the 

 sun and the bright lines in the spectrum of the flame of a 

 lamp. In Dr. Brewster's note-book, dated St. Andrews, 

 Oct. 28, 1 841, this passage occurs :— " I have this evening 

 discovered the remarkable fact that, in the combustion of 

 nitre upon charcoal, there are definite bright rays corre- 

 sponding to the double lines of A and B, and the group 

 of lines a in the space A B. The coincidence 0/ two yellow 

 rays with the two deficient ones at D, -with the existence 

 of definite bright rays in the nitre flame, not only at D but 

 at A, a ana B, is so extraordiimry that it inaicates some 

 regular co)inectlon between the two classes of phenomena." 

 We next have an important experiment made by Fou- 

 cault in 1S49, who pointed out that the electric arc pre- 

 sented us with a medium which emits the rays D on its 

 own account, and which at the same time absorbs them 

 when they come from another quarter. 



The received explanation of this coincidence between 

 the two bright lines of burning sodium vapour, and the 

 two dark lines D in the solar spectrum, which extended 

 the grasp of spectrum analysis from terrestrial substances 

 to the skies, was taught by Prof. Stokes in his lectures 

 about 1852, but was not published. 



In 1S53 the idea was first published by Angstrom.* 

 In his memoir, for the purpose of illustrating the ab- 

 sorption of light, he made use of a principle already pro- 

 pounded by Euler, in his Jhcoria liicis ct caloris, that the 

 particles of a body, in co7iscquence of resonance, absorb 

 principally those ethereal undulatory motions which have 

 previously been impressed upon them. He also endea- 

 voured to show that a body in a state of glowing heat 

 emits just the same ki?ias of light and heat which it 

 absorbs tinder the same circumstances. He further under- 

 took researches on the electric light, and stated that in 

 many cases the Fraunhofer lines were an inversion of the 

 bright lines, which he observed in the spectrum of various 

 metals. 



Early in 1859, Mr. Balfour Stewart independently dis- 

 covered the law which binds together radiation and 

 absorption, establishing it experimentally as an extension 

 of Prevost's law of exchanges in the case of the heat ra) s, 

 and generalising his conclusion for all rays. 



In October of the same year, 1S59, Kirchhoff esti- 

 blished experimentally the same law for the light rays. 



On the occasion of Angstrom's admission to the mem- 

 bership of the Royal Society, General Sabine in his intro- 

 ductory address mentioned that the obstacles opposed by 

 the language in which Angstrom's treatise had bten writien, 

 and by distance from the scene of his investigations, had 

 for three years prevented its very existence from being 

 known to the scientific world at large ; but when once 

 the nature of that treatise became known, the fact was 

 immediately acknowledged, that in Professors Stokes and 

 Angstrom we are bound to recognise the fathers of spectral 

 analysis. Indeed, in the " Optiska Underiokningar" of 

 the latter are to be found many of the fundamental prin- 

 ciples of much that has since been accomplished in that 

 department of scientific inquiry. In his work entitled 

 '■ Recherches sur le spectre solaire," with its atlas of the 

 normal spectrum of the sun. Angstrom has given us an 



• "Upliska UndpiTOkningar :" Tran 

 1853. Translated in Phil. Mag. 4th serii 



. Royal Academy of Stockholn 

 s, vol. ix. p. 237. 



indispensable adjunct for all future students of spectrum 

 analytical investigations. 



We have already sta'ed that Angstrom published 

 memoirs on subjects connected with nearly every depart- 

 ment of physical inquiry. Thus we have papers : — (i) "Sur 

 la polarisation rectiligne et la double refraction dcs cristaux 

 k trois axes obliques'' (Upsala Vetenskaps-Societets Acta), 

 in which he gives the solution of the problem involved in 

 the optical phenomena presented by such crystals which 

 had been sought, but without success, by Neumann and 

 MacCulIogh. (2) On the " Monoklinoedriska kristallernas 

 molekuliira Constanter" (Vet. Akad.'s Handlingar, 1859). 



(3) " Ny nietod at bestiimma kroppars ledningsformaga 

 for Vatme " — New method of determining the capacity for 

 conducting heat in the human body — (Vet. Akad. Forh. 

 1861) ; which contains the first determinations ever given 

 of the absolute values of the capacity for conducting heat. 



(4) " Sur deux inegalilds d'une grandeur remarquable dans 

 les apparitions de la Comete de Halley" (Upsala Vet. 

 Soc. Acta.). This treatise first excited the expectation 

 amongst astronomers of obtaining certain results by means 

 of a single method. (5) " Sur les Spectres des gas 

 simples" {Compies Rendus, 1871). 



These are among the most important of Angstrom's 

 numerous treatises, and in addition we may instance his 

 celebrated monograph, " M^m.oire sur la temperature de 

 laterre" (Upsala Vet. Soc.'s Acta.), as well as a paper 

 belonging to an earlier period, which appeared in the 

 " Denkschriften der Miinchener Academie," 1844, under 

 the title of " Magnetische Beobachtungen bei Gelegenheit 

 einer Reise nach Deutschland und Frankreich." 



As might naturally be expected, numerous scientific 

 Societies sought the honour of numbering Angstrom 

 amongst their members, as for instance : — Kungl. Vet. 

 Akad. i. Stockholm ; Kungl. Vet. Akad. i. Upsala ; the 

 Royal Societies of Berlin, Copenhagen, London, &c. He 

 was, moreover, appointed Corresponding Member of the 

 French Institute ; he twice obtained the Wallmarsk prize 

 of the Vet. Akad. of Stockholm in 1865, in conjunc- 

 tion with Professors Thalen and H. Holmgren, and 

 in 1869 with the former alone. He carried off two 

 other prizes given by the same Society, and once he ob- 

 tained a grant of money for his observations I'rom the 

 University of Upsala, before he had become a mem- 

 ber of the Upsala Vet. Soc, which was the more 

 acceptable to him, since for a long period he reaped 

 a very inadequate pecuniary return for his scientific 

 labours. Partly by the aid of the Slate, but mostly at 

 his own personal expense. Angstrom several times visited 

 the Continent, especially France and Germany. He was 

 absent from Sweden in the years 1S43, 1844, 1859, and 

 during the summers of 1866 and 1867 ; but with one ex- 

 ception he attended all the meetings of the Scandinavian 

 Association for Natural and Physical History. In recog- 

 nition of his great merits, Angstrom was made Knight 

 of the " Order of the North," and Commander of the 

 Vasa Order ist Class, and of the " Crown of Italy." 



THE IRON AND STEEL INSTITUTE 



THIS prosperous and useful association held its sixth 

 summer meeting last week, from the i st to the 4th 

 instant, at Barrow-in-Furness, a town whose rapidity of 

 growth is unparalleled out of America, Twenty-five years 



