496 



NA TURE 



[March 26, 190,; 



A second enlarged edition of Prof. A. Fischer's admirable 

 " Yorlesungen iiber Bakterien " has been published by the 

 firm of Gustav Fischer, Jena. The first edition was pub- 

 lished in 1897, and was very favourably reviewed in these 

 columns (vol. lviii. p. 77, 1S98). The book is now double 

 the size of the original volume, the number of pages having 

 been increased from 186 to 374. Its value as a scientific 

 treatise on bacteriology has thus been increased, and students 

 of the subject may turn to the book with confidence that 

 they will find the present state of knowledge of bacterio- 

 logical science satisfactorily represented in it. 



The additions to the Zoological Society's Gardens during 

 the past week include a Bosnian's Potto (Perodicticus potto) 

 from West Africa, presented by Captain Jas. Startin, R.N. ; 

 a Rhomb-marked Snake (Trimerorhinus rkotribeatus) from 

 South Africa, presented by Mr. George Vanderspar ; six 

 Marbled Newts (Molge marmorata), three Palmated Newts 

 (Molge palmata), three Brown Newts (Spelerpes fuscus), 

 European, deposited; two Herons (Ardea cinerea) t European, 

 received in exchange. 



OUR ASTRONOMICAL COLUMN. 



Astronomical Occurrences in April: — 

 April 6. ioh. 11m. Minimum of Algol (8 Persei). 



9. Ilh. 48m. to I2h. 23m. Moon occults v Leonis 



(mag. 4-5). 

 9. I5h. 16m. to iSh. 48m. Transit of Jupiter's Sat. III. 



(Ganymede). 

 II. Moon partially eclipsed visible at Greenwich : — ■ 

 ioh. 34 '4m. First contact with the shadow. 

 I2h. I3'0m, Middle of the eclipse. 

 130. 51 6m. Last contact with the shadow. 

 Magnitude of the eclipse (S's diameter = 1) 

 = 0-973. 

 15. Venus. Illuminated portion of disc = 0832, 



Mars = o - 985. 

 20-22. Epoch of Lyrid meteoric shower (Radiant 271° 



+ 33°)- 

 26. nh. 54m. Minimum of Algol (8 Persei). 

 29. Sh. 43m. Minimum of Algol (8 Persei). 



Stellar Parallax. — The Transactions of the Astronomical 

 Observatory of Yale University (vol. i. part vi.) contain 

 a valuable determination of the parallax of the ten first 

 magnitude stars in the northern hemisphere by Dr. W. L. 

 Elkin, the director of the Observatory. This investigation 

 is part of a scheme for making a series of researches on the 

 parallaxes of stars of successive orders of magnitude with 

 the Yale heliometer, and was begun in the year 1885. In 

 the volume before us Dr. Elkin gives details of the method 

 of measurement adopted, the several series and comparison 

 stars, the observations and reductions, and finally a dis- 

 cussion of the results. Referring here only to the actual 

 results he obtained, the following table gives the adopted 

 values of the parallax of each of the stars, with their prob- 

 able errors : — 



a Tauri 

 a Auriga? 

 a Orionis 

 a Can. Min. 

 H Geminorum 

 a Leonis 

 a Bootis 

 a Lyrae 

 o Aquilse 

 a Cygni 



Adopted Probable 



Parallax. Error. 



+ 109 ±0014 



0079 O 021 



OO24 OO24 



0-334 0015 



0-056 0-023 



OO24 0'020 



0026 0-017 



0082 0-016 



+ 0-232 o'oig 



-0012 +0023 



Measures of Saturn's Rings. — A series of measurements 

 of the distance between the inner edge of the inner ring of 

 Saturn and the planet itself has been made by Prof. F. E. 

 Seagrave, of Providence. The mean result obtained shows a 

 distance of 3"'6g8 on the preceding side and 4"'oos on the 



NO. I743, VOL. 67] 



following side, and the diameter of the planet itself is given 

 as i7"-6i8. 



A comparison of this result with the mean of the results 

 obtained by previous observers shows that there is no proof 

 of the theory, first advanced by M. Struve in 1851, that the 

 inner ring of the planet was expanding inwards, and that 

 consequently the space between it and the planet was de- 

 creasing (Popular Astronomy, No. 103). 



Observations of Jupiter's Fifth Satellite. — In Bulletin 

 No. 28 of the Lick Observatory, Prof. R. G. Aitken gives 

 the details of the measurements made during 1900 and 1902 

 at the Lick Observatory of the positions of Jupiter's fifth 

 satellite. 



In each set of observations the position of the satellite is 

 referred to that of one of the others, and the time of observ- 

 ation, the position angle, the distance in seconds and the 

 number of settings are given in tabular form. 



The satellite was observed on ten nights, a magnifying 

 power of 270 being used during 1900, and a power of 350 

 during 1902. During the former period the planet itself 

 was occulted by means of a drop of Indian ink on a clear 

 glass plate placed between the micrometer threads and the 

 eye-piece, but during 1902 a piece of suitably placed smoked 

 mica was substituted for the glass plate. 



Observations of the Light of Nova Persei. — The 

 second publication, by the Harvard College Observatory, of 

 the variations in the magnitude of Nova Persei occurs in 

 vol. xlviii. (No. 2) of the H.C.O. Annals. 



About three thousand six hundred magnitude observations 

 have been compiled from various sources bv Mr. Leon 

 Campbell, under the direction of Prof. O. C. Wendell. The 

 time of observation, the original comparison stars (when 

 available), the magnitude of the Nova reduced to the 

 Harvard photometric scale, the name of the observer and 

 a reference number to the publication in which the observ- 

 ation was originally recorded are given for each observation, 

 and the observations are set out in chronological order. 



New Catalogue of Double Stars. — A sixth catalogue of 

 one hundred double stars, discovered by Mr. W. J. Hussey 

 whilst using the 12-inch and 36-inch Lick refractors, is con- 

 tained in Bulletin No. 27 of the Lick Observatory. The 

 previous five catalogues, each containing the names, posi- 

 tions and particulars of one hundred new doubles, have 

 appeared in earlier numbers of the Astronomical Journal 

 and the Lick Bulletins. 



Mr. Hussey calls special attention to two of the stars in 

 the present catalogue, Nos. 507 and 580 respectively. No. 

 507 (D.M. + 49°.95) is a remarkable triplet the components 

 of which are of nearly equal magnitude (A. = 9-3111., 

 B.=9'5m., C. =9'8m.) and form an equilateral triangle, and 

 the observer suggests that the measurements thereof should 

 form a conclusive test for determining personal equations. 

 No. 580 (1 Serpentis) is a probable binary the components 

 of which are equal in magnitude (5'om.) and the proper 

 motion exceedingly small, viz. — 0-004775. and — o"'0582. 



Magnetic Observations During Eclipses. — Dr. L. A. 

 Bauer, of the Coast and Geodetic Survey, Washington, has 

 collected all the available observations of the magnetic varia- 

 tions which are shown to take place during a total eclipse 

 of the sun, and has published them in No. 4, vol. vii. of 

 Terrestrial Magnetism and Atmospheric Electricity. 



It is suggested in the preface to the article that the eclipse 

 variation of the magnetic needle is analogous to the common 

 diurnal variation, and that the causes of the two phenomena 

 are also analogous, inasmuch as the diurnal variation may 

 be caused by the continual eclipse of that side of the earth 

 which, for the time being, is turned away from the sun. 

 For this to be the case we have to premise that these varia- 

 tions are caused by some undetermined radiation from the 

 sun which affects the magnetic needle. 



This suggestion is supported by the following result de- 

 duced from the collected observations, which refer to every 

 eclipse that has taken place since 1870 : — " The precise effect 

 of the eclipse magnetic variation is (1) opposite in the 

 two magnetic hemispheres ; (2) opposite for the morning and 

 afternoon hours." In other words, "the nature of the 

 eclipse variation is analogous to that of the diurnal varia- 

 tion, ditlering from it only in degree." 



Supposing that the magnitude of the effect produced varies. 



