592 



NA TURE 



April 20, 1905 



of a different form of apparatus by Prof. Battelli and 

 F. Maccarrone {Physikalischc Zcitschrift, No. 6). It must 

 be concluded, therefore, contrary to M. Becquerel's views, 

 that such emanations consist neither of fragments of atoms 

 which have lost positive ions nor of the positive ions 

 themselves. 



A NEW method for the preparation of paraffins from 

 their monohalogen derivatives which is described by M. 

 Paul Lebeau in the current number of the Comptes 

 rendus (April lo), is noteworthy on account of the sim- 

 plicity of the reaction and the purity of the gas obtained. 

 Sodium is converted into sodium-ammonium by the action 

 of liquid ammonia, and this, treated with methyl chloride, 

 gives methane, readily obtained in a pure state by lique- 

 faction by means of liquid air. Ethyl and propyl iodides 

 react with the same ease, giving rise to ethane and pro- 

 pane, the purity of which was verified by combustion 

 analysis. It is pointed out by M. Lebeau that as these 

 reactions take place below the boiling point of liquid 

 ammonia there is small probnbilitv of any secondary re- 

 actions taking place. 



.The current number of the Quarterly Review contains 

 an article by Mr. A. E. Shipley on " Pearls and Parasites." 



We have received from Messrs. Isenthal and Co. a well 

 illustrated and conveniently arranged catalogue of technical 

 and laboratory electric measuring instruments and 

 rheostats. 



The issue of the Journal of the Royal Sanitary Institute 

 for April contains a full account of the papers read and 

 the speeches delivered at the conference on school hygiene 

 held at the University of London in February last, and 

 reported in Nature for February 16 (p. 377). 



Many characteristic scenes of the western coast and fjords 

 of Norway are described and illustrated in a pamphlet just 

 issued by the .\lbion Steamship Co., Ltd., Newcastle-on- 

 Tyne, as an itinerary of cruises to be taken this year by 

 the yachting steamer Midnight Sun. 



Messrs. John J. Griffin and Sons, Ltd., have pub- 

 lished a ninth edition of their illustrated and descriptive 

 catalogue dealing with apparatus suitable for the practical 

 study of sound, light, and heat. An examination of the 

 contents of the catalogue shows that a great improvement 

 is taking place in the apparatus employed in the labor- 

 atories and lecture-rooms where physics is taught. 

 Teachers and others should find this catalogue helpful and 

 suggestive. 



OUR ASTRONOMICAL COLUMN. 



.ASTROPHYSICAL WoRK AT THE SMITHSONIAN INSTITUTION. 



— Prof. Langley's report of the work performed in the 

 various departments of the Smithsonian Institution during 

 the year ending June 30, 1904, contains a report by Mr. 

 C. (;. Abbot of the observations made in connection with 

 the solar radiation at the astrophysical observatory. 



.Among many items of interest, the following may be 

 briefly mentioned : — The bolometer apparatus has now been 

 improved to such a state of perfection that a duplicate set 

 for investigating the radiation of stars has been con- 

 structed. A series of experiments with the improved pyro- 

 heliometer has shown that this instrument may now be 

 used with confidence to measure the solar radiation. 



The definition of the long focus mirror has been con- 

 siderably improved by churning the air inside the tube, 

 by protecting the tube from the direct solar rays with a 

 covering of canvas, by employing a number of supporting 

 plates as suggested by Prof. Ritchey in order to preserve 

 the shapes of the mirrors, and by nullifying the vibrations 

 due to traffic by placing indiarubber pads behind the 

 mirrors. Prior to these alterations the solar image was 



NO. 1851, VOL. 71] 



ill-defined ; different parts of it came in focus in different 

 planes, whilst the variation in the focal length of the 

 instrument often amounted to 10 feet during a single day. 

 Now the image is much better defined ; all parts of it are 

 focused in the same plane, and the focal length never 

 varies so much as 12 inches during a day. 



Well marked variations, amounting to 10 per cent, of 

 the total, have been recorded in the value of the solar 

 radiation, and Mr. Abbot expresses a strong hope that, on 

 combining the solar radiation and atmospheric transparency 

 results, long range climate forecasting will ere long be- 

 come possible. 



Value of the Astronomical Refraction Constant. — 

 The third volume of the Publications of the Granducal 

 Observatory at Heidelberg contains 234 pages devoted to 

 the discussion of the results obtained by M. L. Courvoisier 

 in a research undertaken by him for the determination of 

 the refraction constant. 



The instrument employed was a 6-inch Repsold meridian 

 circle, which, together with its various constants, is de- 

 scribed at length. Two hundred stars were observed, and 

 the observations and their peculiar errors are discussed. 

 The meteorological data for several periods during each 

 observing day are next given, the observations extending 

 from June 3, 1899, to July g, igoi, and this table is 

 followed by sections dealing with the stellar, latitude, and 

 declination observations respectively. 



The value obtained for the refraction constant is 

 60". 161 +o"o37. 



Reality of Various Features on Mars. — In No. 4007 

 of the Asironomische Nachrichien Signor V. Cerulli, of 

 Teramo, discusses the actual subjectivity of various Martian 

 phenomena, as seen in the telescope, from a physiological 

 standpoint. Having observed Mars regularly for ten 

 years, he appears to have arrived at the conclusion that 

 the actual existence of these features is as much a subject 

 for physiological as for astronomical investigation. He 

 states that the phenomena observed are so near to the 

 limit of the range of the human eye that in observing 

 them one really experiences effects accompanying " the 

 birth of vision." That is to say, the eye sees more and 

 more as it becomes accustomed, or strained, to the delicate 

 markings, and thus the joining up of spots to form 

 " canals " and the gemination of the latter follow as a 

 physiological effect, and need not necessarily be subjective 

 phenomena seen by the accustomed eye. 



Stonvhurst College Observ.^tory. — In addition to the 

 results of the meteorological and magnetic observations 

 made during 1904, Father Sidgreaves's annual report 

 briefly refers to the solar and stellar spectroscopical work 

 carried out at Stonyhurst during last year. 



Two series of spectrograms of j3 Auriga and y Cassio- 

 peiae were commenced, and the results already obtained 

 are very promising. A short table showing sun-spot areas 

 and the range of the magnetic declination appears to con- 

 firm the connection between these two values for the years 

 1898-1904. The spectra of sun-spots in the green and 

 violet regions have been photographed with a Rowland 

 grating spectroscope, and a number of experiments have 

 been made with the view of photographing the spot spectra 

 in the red region. 



Nature of Sun-spots. — In the April number of the 

 Bulletin de la Sociiii astronomiquc de France .Abb^ Th. 

 Moreux re-discusses his theorv concerning the formation 

 and nature of sun-spots in the light of data more recently 

 acquired, more especially during the great spot of February 

 last. He gives numerous drawings of this spot, and 

 several schematic diagrams showing the possible arrange- 

 ment of the photospheric clouds in and over the spot, and 

 arrives at the conclusion that spot areas are analogous to 

 anti-cyclonic areas in the terrestrial atmosphere. 



Instructions to Solar Observers. — Amateur observers 

 of solar phenomena will find the instructions to solar 

 observers, formulated by the " commission solaire " of the 

 Soci{'!ti5 astronomique de France, of great use and interest. 

 Chapter v. is published in the .April Bulletin of the society, 

 and deals with daily spectroscopic observations of the 

 chromosphere and prominemps by the Lockyer-Janssen 

 method. 



