April 27, 1906.] 



SCIENCE. 



679 



Charles A. Parsons, Professor J. H. Poynting, 

 Professor Arthur Schuster, Mr. Leonard Hill, 

 Professor H. Moissan, and Sir James Dewar. 

 A RECENT Friday evening lecture at the 

 Royal Institution was given by Professor P. 

 Zeeman, of Amsterdam University, on ' Re- 

 cent Progress in Magneto-Optics.' According 

 to the London Times, Professor Zeeman gave 

 a general review of the experimental researches 

 on the relation betwen magnetism and light 

 which had occupied him during the last few 

 years. His observation, made in 1896, of a 

 slight widening of the spectral lines of sodium 

 under the influence of a magnetic field was, 

 he said, the origin of his work, which he car- 

 ried on in the light of the theory of electro- 

 magnetic and optical phenomena developed by 

 H. A. Lorentz. In accordance with this 

 theory he found that in a strong magnetic field 

 certain spectral lines were divided into three 

 components, when the magnetic force was at 

 right angles to the direction of propagation of 

 the light, and further, that the middle one of 

 these components was plane-polarized in a di- 

 rection different from that of the two outer 

 ones. When the magnetic force was parallel 

 to the direction of the propagation of the light, 

 the lines split up into two components, each 

 circularly polarized but in opposite directions. 

 From these phenomena it could be inferred 

 that in a luminous gas all vibrations arose 

 from the negative electrons, and the value 

 deduced for the ratio of the charge to the mass 

 of the electron was of the same order as that 

 obtained from the study of the cathode rays. 

 Professor Zeeman next considered the rotation 

 of the plane of polarization close to an absorp- 

 tion band, and then the double refraction and 

 resolution of the absorption lines. Finally, 

 he discussed the behavior of different spectral 

 lines in the magnetic field. In many metallic 

 spectra a number of the lines occurred which 

 were closely related and formed so-called 

 series. It was foimd that all lines of the 

 same series were split vip in the same manner, 

 e. g., all were resolved into triplets, or sextets, 

 or nonets; moreover, not only was the general 

 type of subdivision the same, but even the 



amount of separation, measured in oscillation 

 frequency. A second law was that the corre- 

 sponding series of different elements also 

 showed the same type of resolution and the 

 same amount of separation. The conclusion 

 seemed to be that all the lines of a series were 

 emitted by one oscillating system, and that, 

 therefore, there were as many series in the 

 spectrum of a substance as there were oscilla- 

 ting systems in its atom; and that the oscilla- 

 ting mechanism was the same in different ele- 

 ments. He thought there could be no doubt 

 that spectrum analysis and especially the 

 magnetization of the spectral lines would give 

 a clue to the inner structure of the atom. 



The Scottish Geographical Magazine states 

 that for some time past preparations have 

 been made for a French Colonial Congress, to 

 he held at Marseilles in September next, under 

 the presidency of M. J. Charles Roux, the well- 

 known writer on colonial subjects. From the 

 intimate connection which exists between 

 marine and colonial affairs, it has been decided 

 to extend the scope of the congress by the addi- 

 tion of an exhibition, intended to illustrate 

 all matters connected with the scientific study 

 of the sea and its fisheries. Its organization 

 was entrusted to M. Charles Benard, president 

 of the Oceanographical Society of the Golfe de 

 Gascogne, who has done more than any one else 

 to further the study of oceanography in France 

 within recent years. In recognition of the 

 fact that the sea knows no political boundaries, 

 it was wisely decided to give the exhibition an 

 international character, and the cooperation of 

 the leading oceanographers of all nations was 

 invited. A British committee was formed un- 

 der the presidency of Sir John Murray, in- 

 cluding representatives of the principal organ- 

 izations connected with the study of ocean- 

 ography and marine biology in this country, 

 and under its auspices a representative British 

 exhibit has been got together. The society 

 will be represented at Marseilles by Captain 

 Wilson Barker, and among other exliibits, has 

 sent the model of the Antarctic exploring 

 ship, Discovery, a special feature of the ex- 

 hibition being the illustration of the great 



