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NATURE 



[January 23, 1913 



■duced a long series of researches published in scien- 

 tific journals in this country, as well as in Germany. 

 These may be grouped under the following heads : — 

 Absorption and secondary radiation of kathode rays, 

 photoelectric effects, electrical conductivity of gases 

 and of flames, phosphorescence and radio-activity, in- 

 cluding its application to medical work. We wish 

 every success to this active and progressive institute. 



The receipt of the notification of the Metropolitan 

 Gas Referees for the current year serves as a reminder 

 that the qualitv of the gas supplied to the County ot 

 London is subject to severe control. The threat ot a 

 monopoly caused by the amalgamation of various gas 

 companies led to increased Parliamentary control, and 

 commencing with the City of London Gas Act, 1868, 

 there are several Acts dealing with the London gas 

 supplv, the latest being the London Gas Act, 1905. 

 Subject to these Acts, the details of the methods to 

 be used in gas-testing are left to three gas referees, 

 who have to prescribe and certify the situation and 

 number of the testing places, the apparatus and 

 materials for testing the illuminating power, calorific 

 power, purity and pressure of the gas provided by 

 the companies. The notification of the gas referees 

 gives the methods prescribed in detail. The con- 

 trolling authorities (the London County Council and 

 Corporation of the City of London) have also certain 

 discretionary powers as to the times of testing, and 

 these authorities also appoint the gas examiners. 



Messrs. Charles Griffin and Co., Ltd., have 

 published a tenth edition of an " Elementary Manual 

 on Applied Mechanics," by Mr. A. Jamieson. Many 

 new examination questions have been added, and the 

 symbols agreed to by the International Electrotech- 

 nical Commission, held in Turin in 191 1, have been 

 included. 



Messrs. J. Wheldon and Co., 38 Great Queen 

 Street, Kingsway, VV.C, have just issued a catalogue 

 (No. 60) of books and papers on microscopical science 

 ill most of its branches. The catalogue includes a 

 number of valuable works, both ancient and modern, 

 and the classification makes it easy to find the works 

 available in the various departments of microscopy. 



OUR ASTRONOMICAL COLUMN. 



Nova Geminorum, No. 2. — The photometric and 

 spectroscopic observations of Nova Geminorum, No. 2, 

 made at the Harvard and Arequipa Observatories, are 

 discussed in Circulars 175 and 176 of the Harvard 

 College Observatory. 



Prof. Wendell's magnitude observations shove 

 several fluctuations, with maxima on March 14, 17, 

 23, 30, and April 5; the magnitude increased con- 

 siderably during the night of March 14. 



The spectra were taken between March 13 and June 

 5, 1912, inclusive, and are discussed by Miss Cannon ; 

 some are reproduced in the second circular. On March 

 :3_ the spectrum was not of the usual nova type, i.e. 

 bright lines accompanied by dark lines; but was of 

 the class F, (Procyonian) type, with slight variations, 

 having dark lines only ; a reproduction of the spectrum 

 of Procyon is placed above the nova spectrum on the 

 plate accompanying the circular, and shows the simi- 



No. 2256, VOL. go] 



larity very strikingly. Miss Cannon remarks on the 

 fact that the earliest spectrum of Nova Persei (2) also 

 lacked bright lines, and that these are the only two 

 novae of which the spectrum has been secured while 

 the star's light was still rising to its primary maxi- 

 mum. The spectrograms taken on March 14 show 

 the spectrum in a transitional state, the characteristic 

 '■ nova spectrum " being fully developed on March 16. 

 The bright band at K, faint on March 20, had dis- 

 appeared by March 22, only a narrow dark line re- 

 maining ; on March 27 a brightening in the region of 

 the spectrum near ^4640 was noticeable, the con- 

 tinuous spectrum was faint, and the dark hydrogen 

 lines not clearly seen, but on March 30 both the con- 

 tinuous spectrum and the dark hydrogen lines were 

 again more intense, the latter being distinctly double. 

 A spectrum taken on May 10 is stated by Miss Cannon 

 to show increased intensities for bands at A.A4640 and 

 5016, while a bright band appears on the less refran- 

 gible edge of Hy ; this probably represents the appear- 

 ance of the nebula line 500S and the line which ap- 

 peared during the nebula stage of previous novse at 

 4365- 



The Variable Star 87, 191 1. — Froin time to time 

 we have referred in these columns to Mr. D'Esterre's 

 notes describing a possible nova in the constellation 

 Perseus. The star was conspicuous on plates taken 

 by Mr. D'Esterre on November 13 and 21, 1911, but 

 did not appear on three previous dates. Prof. E. C. 

 Pickering now states, in Circular 176, that Irom an 

 examination of the Harvard photographs. Miss Cannon 

 finds that the star was of the eleventh magnitude on 

 October 30, 1896, September 17, 1899, and January 

 28, 1902, but was not visible on sixty-eight other 

 plates, including one taken, with sixty minutes' ex- 

 posure, on November 3, 1885, which shows faint stars. 

 Prof. Pickering concludes that this object is certainly 

 not a nova, but appears to be a variable star with a 

 large range which is bright during a relatively short 

 portion of its variations; the period does not appear 

 to be uniform, and he suggests that the object pos- 

 sibly belongs to the U Geminorum and SS Cygni 

 class of variable stars. 



The Transit of Mercury, November 14, 1907. — 

 Prof. Donitch observed the transit of Mercury which 

 took place on November 14, 1907, from a special 

 station established at Assuan. The chief observa- 

 tions were spectroscopic, the spectra being taken with 

 a special spectrograph, at the times of internal con- 

 tacts, the slit coinciding with the sun's limb. The 

 resulting spectra show no lines other than those of 

 the solar spectrum, and lead Prof. Donitch to the 

 conclusion that the planet does not possess an atmo- 

 sphere extending beyond 15 km. from its surface; 

 but for the present he hesitates to consider this con- 

 clusion as rigidly established. (Bulletin de I'Acaddmie 

 Impdriale des Sciences de St. Pdtershourg, No. 17.) 



.Astronomical Annuals. — We have received M. 

 Flammarion's " .Annuaire Astronomique," for 1913, 

 and the " Anuario " of the Madrid Observatory. In 

 addition to its usual complete series of tables and 

 ephemerides, the former contains useful illustrated 

 reviews of the progress of astronomy and meteorology 

 during 1912, several special articles, and a frontispiece 

 showing six untouched photographs of the annular 

 solar eclipse of April 17, 1912. 



The "Anuario," besides the ordinary tables and 

 ephemerides, has a popular article on new stars, a 

 long article on the determination of azimuths in the 

 field, an interesting review of solar physics, with 

 special reference to the development of the spectro- 

 heliograph, and a risumi of the solar and meteoro- 

 logical ob'iervations of 19 11 and 1912. 



