57^ 



NATURE 



[October 9, 1890 



phecy of the foreigner proved by its fulfilment the errors of the 

 Chinese mathematician, who retired in disgrace from the position 

 which he held. He went back to his home to write the book 

 called "The Inevitable Exposure," which contained a series of 

 calumnies and grossly untrue accusations against the Jesuit 

 fathers. This bad book made him much more notorious than 

 his works on mathematics. The unscrupulous enemies of the 

 Westerns have reprinted it again and again, and they still do so. 

 Very different was the tone of Mei Wu-ngan, who was invited 

 three days in succession by the Emperor Kanghi to converse with 

 him upon mathematical subjects. He had a fondness for mathe- 

 matics, and read voraciously. He was therefore in a position to 

 criticize Western knowledge in an appreciative manner. 



The additions to the Zoological Society's Gardens during the 

 past week include two Grizzly Bears {Ursus ho7-ribilis) from the 

 Missouri Brakes, Montana, U.S.A., presented by Mr. Ewen 

 Somerlid Cameron ; a Raccoon {Procyon lotor) from the Catskill 

 Mountains, New York State, presented by Mr. James H. 

 Frodsham ; a Greater Black -backed Gull {Larus marinus), a 

 Herring Gull {Larus argentatus), British, presented by Mr. A 

 M. Bailey ; a Common Tern [Sterna hirundo), British, presented 

 by Mr. A. C. Howard ; two Mississippi Alligators {Alligator 

 mississippiensis) from the Mississippi, presented by Miss Edith 

 Baker ; a Macaque Monkey (Macacus cynomolgus (, ) from 

 India, a Great Kangaroo {Macropus giganteus <J ) from Aus- 

 tralia, deposited ; a Horned Screamer (Palamedea cornuta) from 

 the Amazons, three Violet Tanagers {Euphonia violacea) from 

 Brazil, an Ocellated Sand Skink {Seps ocellata), South European, 

 purchased ; a Chestnut-breasted Duck {Anas castanea) from 

 Australia, received in exchange ; a Crested Pigeon {Ocyphaps 

 lophotes) bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 

 Objects for the Spectroscope. 

 Sidereal Time at Greenwich at lo p.m. on October 9 = 

 23h. 13m. 52s. 



(i)G.C. 4892 



(2) G.C. 4921 



(3) X Aquani... 

 (4)fPegasi ... 



(5) 19 Piscium 



(6) R Aquilce 



Mag. 



6 

 Var. 



Colour. 



R.A. 1890. Decl. 1890. 



Yellowish-red. 



Yellowish-white. 



Red. 



Very red. 



h. m. s. 



22 59 26 



23 10 22 

 23 u 9 



22 40 26 



23 40 46 

 19 I 5 



-f 5 46 



4-11 40 



+ 2 52 



Remarks. 



(i and 2) Neither of these nebulae have yet had their spectra 

 recorded. The first of them is about 4' long by 2' broad, and 

 has been described as "a streak tapering at each end "; in the 

 General Catalogue it is described as "pretty bright ; consider- 

 ably large; much elongated in the direction il°'9; between 

 two stars." The second is described as " considerably bright ; 

 pretty small ; irregularly round ; pretty suddenly brighter in 

 the middle." They are both very conveniently situated for 

 observation. 



(3) The spectrum of this star is a very fine one of Group II. , all 

 the bands being wide and dark. Carbon comparisons will prob- 

 ably be the most valuable observations of this star, the cha- 

 racter of the spectrum indicating that the flutings should be 

 considerably bright. 



(4) Secchi thought that this star had a banded spectrum, but 

 Duner states that it is one of the solar type (" Sp. W.a ! du type 

 le plus pur"). It still requires observing with reference to 

 Groups III. and V. 



(5) The spectrum of this star is one of the very finest of its 

 class (Group VI. ). It has been observed in considerable detail 

 by Vogel and Duner. All the principal and secondary bands 

 are well visible. The carbon band 6 (A. 564) is stated by Duner to 

 be feebler than the others, and so far as we yet know this is the only 



NO. TO93, VOL. 42] 



band in which any considerable variation is established. It will 

 be remembered that this is the cometary band which varies 

 most, but in comets it varies in position also. It seems possible, 

 therefore, that it may also change in position as well as in 

 intensity in stars of Group VI. Comparisons with a spirit-lamp 

 flame would easily decide this point. 



(6) This variable has a well-marked spectrum of Group II. 

 Duner describes it as "very fine," and states that the bands are 

 very wide and dark throughout the spectrum. The period is 

 about 345 days, and it ranges from 6 '4-7 '4 at maximum to 

 io*9-ll"2 at minimum. The star falls in species 9 of the sub- 

 division of Group II., and if it behaves like other variables with 

 similar spectra, bright lines should appear at or about maximum. 

 The spectrum should also be observed for brightenings of the 

 carbon flutings. A. Fowler. 



Observations of Comets. — Prof. E. E. Barnard, of Lick 

 Observatory, contributes a note on Comets 1889 I. and II. to 

 the Astronomical Journal, No. 225, and makes some suggestions 

 as to the possibility of seeing the short-period comets at aphe- 

 lion. The majority of observers neglect comets as soon as they 

 become faint or difficult to see. Prof. Barnard has made it a 

 point to take up comets when they have been dropped elsewhere, 

 and to observe them as long as they can be seen. Comet 1889 I, 

 has been observed at Lick Observatory from September 2, 1888, 

 to August 18, 1890— that is, for very nearly two years ; and 

 Comet 1889 II. from March 31, 1889, to August 24, i890--that 

 is, for 16 months 24 days : hence the duration of visibility of 

 each exceeds that of the great comet of 181 1, which was fol- 

 lowed for 16 months 20 days. At the observation of Comet I. 

 1889, on August 17, its distance from the sun was 6-25 times 

 the earth's mean distance. On August 24, Comet II. 1889 was 

 5-06 times the same unit from the sun, and Prof. Barnard thinks 

 he will be able to follow it for quite six* months longer. The 

 following are the aphelion distances of short-period comets 

 (excepting Tuttle's) recognized at more than one return: — 



Encke's 4*10 Brorsen's ... 5"66 



Tempel's IL ... 4-66 D'Arrest's ... 572 



Tempel's I. ..: 4-82 , Faye's ... 5*92 



Swift's 1880 ... 5-14 Biela's ... 6-19 



Winnecke's ... 5*50 

 It will be seen that Comet I. 1889 is now being observed at a 

 distance from the sun greater than it is possible for any of the 

 short-period comets to attain. It would appear, therefore, that 

 some of the latter class of comets ought to be followed through- 

 out their entire orbits. 



Photographing Stars in the Daytime.— In the .<4.r/r^- 

 nomica:l J ournal iox September 16, 1889, Prof. Holden gave an 

 elementary theory of the subject of photographing stars projected 

 against a bright background. He showed that, if the intrinsic 

 brilliancy of a star be ten times as great as its background, the 

 photographic image in the Lick telescope was 4124 times 

 brighter than that of the sky. It was also proved that small 

 photographic contrasts of this character could be increased with 

 a given telescope by simply cutting down the aperture. 

 Recently, Prof. Holden writes {Astr. Journ., September 19^ 

 1890), " the question has been examined experimentally by Mr. 

 W. W. Campbell and myself, using the great telescope (focus, 

 570 inches) and apertures of 33, 15, 8, and 4 inches. Photo- 

 graphs of Venus, Mercury, the moon, and of Alpha Lyrce have 

 been taken in broad daylight (2 to 5 p.m.) with the apertures 

 named, with a constant exposure of o'i3s., and on Seed 26 

 plates. In general, the smallest apertures used have given the 

 darkest images, as demanded by the theory." 



PHYSICS AT THE BRITISH ASSOCIATION. 

 TN Section A, nine Reports of Committees and fifty-four 

 ■*■ papers were read. Perhaps the distinguishing character- 

 istic of the Section is its tendency to bifurcation on the slightest 

 provocation. Several Sections do not meet at all on the Satur- 

 day, and manage to get through their business comfortably by 

 the Tuesday. Not so Section A. On the Saturday, under the 

 influence of electrolytical attractions and repulsions, there oc- 

 curred a dissociation of the Section into its constituent elements, 

 accompanied by a migration of ions from places of high poten- 

 tial (in a Bramwellian sense) to places of low, or vice versd. In 

 accordance with the law of ionic migration enunciated by Sir 

 Frederick at the concluding meeting, the ions collected at the 



