350 



NA TURE 



\_Fcb. 



[886 



The additions to the Zoological Society's Gardens during the 

 past week include two Maholi Galagos (Galago maholi) from 

 West Africa, presented by Mrs. Max Michaelis ; a Macaque 

 Monkey (Macacus cynomol^iis] from India, presented by Mrs. 

 Corbet ; an Indian Otter {Lutra ttair i ) from Ceylon, presented 

 liy Capt. J. C. Withers ; a Ring-tailed Coati {Nastia rufa i ) 

 from South America, presented by Lieut. J. H. N. Theed, R.N. ; 

 a Red-bellied Waxbill (Estrdda nihriveniris) from West Africa, 

 presented by Mrs. T. Johnson ; two Alligators (Alligator missis- 

 sipfiiiisis) from the Mississippi, presented by Mr. F. J. Dawe ; 

 a Malbrouck Monkey ( Cercopithecus cynosuriis 9 ) from West 



.\frica, two Lemurs {Lemur <5 i ) from Madagascar, 



a Common Boa {Box constrictor), an Anaconda {Eunectcs 

 murinus) from South America, deposited ; a Great Kangaroo 

 (Macroptts giganteiis), born in the Gardens. 



OUR ASTRONOMICAL COLUMN 

 The Double-Star 6i Cygni. — The determination of the 

 orbit of this double-star has hitherto baffled those astronomers 

 who have attempted to deduce it from the numerous measures 

 which have been made. Thus one computer finds the relative 

 motion of the components to be rectilinear, another hyperbolic, 

 and another circular, but in no case have the determinations 

 been altogether satisfactory. Recently, however. Dr. C. W. 

 Peters, of Kiel, has succeeded in obtaining elliptic elements, 

 with a periodic time of 782 '6 years and angle of eccentricity 

 = 10°, which appear to represent the great mass of observations 

 which have been made from the earliest times down to 1883, 

 with considerable accuracy. Herr Peters has computed the 

 following ephemeris from his elements : — 

 Epoch ... 1885-0 ... I886-0 ... 1887-0 ... 188S-0 

 Position ... 119° 44' .. 120° 7' ... 120^ 31' ... 120' 55' 

 Distance ... 2o"-6o ... 2o"-7i ... 2o"-8t ... 2i''<)2 

 Taking the parallax of 61 Cygni to be o"-45, it appears 

 from these elements that the combined mass of the system is 

 about one-half of the sun's mass, whilst the mean distance 

 between the components is about 70 times that of the earth 

 from the sun. 



The Zodiacal Light. — In October 1S83 Prof. Arthur Searle 

 presented to the American Academy of Arts and Sciences a 

 very valuable paper on the zodiacal light, in which he had col- 

 lected and reduced on a uniform system the evening observations 

 of all the principal observers. The principal points then brought 

 out were that in all probability the apparent changes in the 

 latitude of the zodiacal light were due mainly, if not entirely, 

 to tlie effect of atmospheric absorption, and that the method of 

 observation by drawing outlines must be replaced by careful 

 photometric observations if definite knowledge was to be sub- 

 stituted for the vague information we now possessed as to the 

 " Gegenschein," the "zodiacal bands," &c. ; and Prof Searle 

 concluded with the suggestion that the ordinary meteoric theory 

 would gain greatly in simplicity by the substitution of meteoric 

 dust scattered generally throughout the solar system for the 

 meteoric rings that have been usually imagined. Prof Searle 

 has continued his investigations in a recent memoir, in which he 

 corrects, for the effect of atmospheric absorption, Jones's obser- 

 vations of what the latter called the "stronger light" at the 

 elongation 60°, whether made in the morning or evening. The 

 result of the inquiry is to confirm the view arrived at previously, 

 that atmospheric absorption largely affects the apparent position 

 of the zodiacal light, and Prof Searle again lays stress on the need 

 for photometric observations. Prof. Searle concludes that, after 

 correcting for atmospheric ab-orption, there seems reason to think 

 that the zodical light has had, during the present half-century, a 

 more northern latitude near the longitude 180° than near the 

 longitude o". He also shows, from a careful study of the dis- 

 tribution of the stars in the DurcJimusterniig, that " upon the 

 meteoric theory of the zodiacal light it is to be expected that a 

 continuous zodiacal band should be present ; but the question of 

 its actual visibility is complicated by the slight maxima of stellar 

 density which are situated along those parts of the ecliptic most 

 readily accessible to obicrvation from stations in the northern 

 hemisphere." An interesting result is obtained from an examin- 

 ation of the elements of the 237 asteroids first discovered, from 

 which it would seem that "the belt of sky occupied by the 



projections of the orbits of" these asteroids "presents certain 

 peculiarities which correspond to those of the zodiacal light, 

 and suggest the hypothesis that the light may be partly due to 

 minute objects circulating in orbits like those of the smaller 

 planets." 



ASTRONOMICAL PHENOMENA FOR THE 



WEEK 1 886 FEBRUARY 14-20 



/pOR the reckoning of time the civil day, commencing at 



^ Greenwich mean midnight, counting the hours on to 24, 



is here employed. ) 



At Greenwich on February 14 

 Sun rises, 7h. i8m. ; souths, I2h. 14m. 23 -7s. ; sets, I7h. Iim. ; 

 decl. on meridian, 12° 56' S. : Sidereal Time at Sunset, 

 2h. 50m. 

 Moon (Full on February 18) rises, I2h. 34m. ; souths, 2oh. 27m. ; 

 sets, 4h. 2im.* ; decl. on meridian, 18° 22' N. 



cultaUoits of S'ars by the Mo.ti (visible at Greenwich) 



Corresponding 

 5,=,,- M=,» n;.,„ R.,„ angles from ver- 



Mercury in conjunction with and II 22' 

 south of Venus. 



CHEMICAL NOTES 

 We have already mentioned M. Konovaloff's researches iiito 

 contact actions, published in the Jownal of the Russian 

 Chemical Society (18S5, vii. and viii.) The following conclu- 

 sions of his inquii-y are worthy of being noticed : — The capacity 

 of solid bodies for condensing gases on their surfaces is gene- 

 rally recognised, but their capacity of dissociating them under 

 certain conditions must also be recognised now as a property of 

 all solid bodies, although shared in by them indifferent degrees. 

 Platinum enjoys this property to a high degree, but also 

 many other solid bodies, glass among them, the intensity of its 

 contact action obviously depending upon several circumstances : 

 its chemical composition, the structure of its surface, and its tem- 

 perature, as also upon the density of the gas it is brought in 

 contact with. It being so, it appears possible, in the author's 

 opinion, that in the dissociation phenomena studied by Sainte- 

 Claire Deville (and having so great an importance for the theo- 

 retical discussions upon the dynamics of chemical reactions), the 

 dissociation observed was a consequence of the contact action of 



