486 



NATURE 



[February 9, 191 1 



three parts of coarse sand. Tests conducted at the Uni 

 versity of Illinois show that the reinforced concrete column 

 possesses about double the strength of the plain steel 

 column prior to reinforcement. 



The 'London representative of the firm of E. Merck, of 

 Darmstadt, desires us to say that the " Index " referred 

 to last week (p. 453) can be obtained at the address of 

 the London house, 16 Jewry Street, E.C., and that the 

 price of the book is ds. 6d. 



' The first number of The Irish Review, a monthly 

 magazine of Irish literature, art, and science, will be 

 issued next month. The review will be for Ireland what 

 such periodicals as The Quarterly Review, The Edinburgh 

 Review, Le Mercure de France, have been for neighbour- 

 ing countries. It will compete with no existing periodical, 

 and will publish in its literary pages nothing of merely 

 ephemeral interest. In each number will be an authori- 

 tative article on a subject of scientific or economic research 

 33 applied to Ireland. 



Messrs. Flatters and Garnett, Ltd., 32 Dover Street, 

 Manchester, have issued two new catalogues. One pro- 

 vides interesting particulars of a series of new lantern-slides, 

 and is supplementary to the catalogue of lantern-slides 

 published by this firm in November, 1909. Attention may 

 be directed specially to the slides illustrating plant associa- 

 tions, by Mr. W. B. Crump; bird photographs from recent 

 negatives ; and the reproduction and development of Pintis 

 sylvestris. The second list deals with optical lanterns and 

 accessories. One novel item in the latter is a combined 

 lantern-screen and stand which can be erected in two 

 minutes. 



OUR ASTRONOMICAL COLUMN. 



Nova. L.icert^. — In his note to the Academy of Sciences 

 {Comptes rendus, January 23) describing the spectra of 

 Nova Lacertae secured at the Meudon Observatory on 

 January 15, M. P., Idrac directs attention to the great 

 width and the structure of the bright hydrogen lines. 



Each of the hydrogen lines H/3-Hf extends over about 

 40 Angstroms, and in HjS, H7, and H5 there are strong 

 maxima at about 12 Angstroms from the centre of each 

 band towards the red ; the photograph is probably too 

 weak to show them in He and H^. The band at K 464 

 is as strong as the hydrogen lines, and has hazy borders, 

 its width being about 50 Angstroms ; there is also a 

 bright line at about \ 437. 



The spectra secured are too narrow to show absorption 

 lines definitely, but one is suspected on the more refrangible 

 side of H7. Altogether, the spectrum appears to be of 

 the nova rather than of the long-period variable type. 



Mars and its Atmosphere. — A number of drawings of 

 the surface features of Mars, reproduced and described in 

 Circular No. 5 of the Transvaal Observatory, are of 

 interest, inasmuch as they represent • the observations of 

 two unbiassed observers ■ using a 9-inch refractor under 

 favourable conditions. The observations were made during 

 the latter part of 1909 by Mr. Innes and Mrs. H. E. Wood, 

 and are depicted on forty -two separate discs ; Mrs. Wood 

 also contributes a composite map embodying the details 

 seen on her separate sketches. 



Mr. Innes saw many fine and elusive shadings, but no 

 " canals," in the usual acceptance of the word, were seen 

 by him. He directs special attention to the two conju- 

 gate, diametrical, double canals usually shown crossing 

 Hellas, and states that he was never able to see more 

 than a curious curved shading. On the other hand, Mrs. 

 Wood, in her drawing of October 25 (No. 40) and on the 

 composite map, shows Peneus and Alpheus in their con- 

 ventional forms. 



In Bulletin No. 180 of the Lick Observatory Prof. 

 Campbell and Dr. Albrecht describe the results secured in 

 an attempt to obtain evidence for Water vapour and oxygen 

 in the Martian atmosphere by the broadening or duplica- 



NO. 2154, VOL. 8-~. 



tion of the corresponding terrestrial lines on large-dis- 

 persion spectrograms. As red-sensitive plates are now 

 readily procurable, it was expected that this application 

 of the Doppler-Fizeau principle, which occurred to Prof. 

 Campbell in 1896, might prove fruitful. Spectrograms 

 were secured, some under excellent conditions, in January i 

 and February, 1910, with a specially designed grating-; 

 spectrograph made at the observatory, and the displace-, 

 ments of the lines carefully measured. 



The results indicate that the amount of water-vapour 

 existing in the planet's atmosphere on February 2, 19 10, 

 was certainly less than one-fifth that existing above Mount 

 Hamilton, where the air temperature was 0° C, the 

 relative humidity was 33 per cent., and the absolute 

 humidity was 1-9 grams per cubic metre ; the zenith 

 distance at mid-exposure was 55°. The amount of oxygen 

 above unit area on Mars was, apparently, also small as 

 compared with that in the earth's atmosphere. 



CoMETARY Theories. — In No. 4466 of the Aslronomische 

 Nachrichten Messrs. Roe and Graham, of the Syracuse 

 University, suggest a new theory of comets which they 

 believe to be based on phenomena in accordance with 

 modern mathematical physics. Briefly, it is that the sun, 

 as an intensely heated body in which violent chemical 

 action is taking place, emits abundant streams of negative 

 electrons, and so acquires a positive charge. Other bodies, 

 such as the earth and comets, will act similarly under the 

 action of some agent intimately associated with the ultra- 

 violet light radiations which they receive. As the comet 

 approaches the sun, the positive charge will tend to 

 increase, and the mutual repulsion of the charged particles 

 will overcome the relatively small cometary gravity, thus 

 producing streamers away from the comet and the sun.- 

 Various associated problems are discussed in the paper, 

 and various desirable lines of research are briefly 

 enunciated. 



In No. 4468 of the same journal Prof. Eginitis also 

 discusses the physical constitution of comets as exemplified 

 by the phenomena attending the recent passage of Hallev's 

 comet. After May 21, 1910, the tail appeared to be miich 

 brighter than before, and Prof. Eginitis attributes this 

 to the fact that then we were looking at it by directlv 

 reflected solar light — the side illuminated by the sun's ravs- 

 was exposed to us. Therefore, he argues, the rnaterial 

 composing comets is but slightly luminous, and we only 

 see it clearly when it is acting as a reflector of the solar 

 light. From this it follows that the physical constitution 

 of comets is not purely gaseous— the comet is a mixture 

 of gas with solid corpuscles. 



Polarisation in the Spectrum of o Ceti. — When, in 

 1898, it was found that the bright H7 line in the spec- 

 trum of Mira was triple, it was suggested that the pheno- 

 mena might be due to the Zeeman effect produced by 

 magnetic activity in the star. Polariscopic observations 

 were not then possible, and the faintness of Mira in 1890 

 defeated the preparations made for the maximum of that 

 year. 



During the maximum of 1909 preparations were again 

 made at the Lick Observatory, and photographs were 

 secured, but no definite general conclusion accrued. As 

 Dr. W'right explains, in Lick Observatory Circular, N^' 

 183, the whole problem is hedged with grave diflTicult: 

 chief of which is that introduced by the possibly consid 

 able changes of direction of the magnetic field in the st 

 All that can be deduced definitely from his observatic 

 is that they show that the multiple character of the \\r 

 is not due to a magnetic field maintaining a const; 

 direction throughout the source. 



The Earth's Action on Sunlight and Heat. — Mr. 

 James D. Roots sends us a pamphlet in which ' 

 enunciates a theory to answer the question: "What ]■ 

 comes of the Sunlight and Heat Absorbed by the Earth? 

 Mr. Root believes it is converted to " radio-activity, a 

 then by stages of change to electric current," which lea\ 

 the earth at the poles, completing a continuous cycle «u : 

 to earth, earth to sun. The story is not so continuous, 

 and often consists of such statements as " The mn' 

 currents rotate t'ne earth," but it is reassuring to le.i- 

 that Sir J. J. Thomson, in one passage of his' " F.! 

 tricity and Matter," "almost grasps the truth." 



