4S4 



NATURE 



[September 13, 1894 



swallowed up by the lake, but when one of the great downfalls 

 referred to occurred, it would not immediately sink, but would 

 lloat otT across the lake, a great floating island of rock. At 

 about three o'clock an is land of this character was formed 

 estimated to bs about 125 feet long, 25 feet wide, and rising 10 

 10 15 feet above the surface of the lake. Shortly after, another 

 great fall toak place, the rock plunging out of sight beneath 

 the lava. Within a few moments, however, a portion of 

 It, approximately 30 feet in diameter, rose up to an elevation of 

 from 5 to 10 feel above the surface of the lake, the molten lava 

 streaming from its surface, quickly cooling, and looking like 

 a great rose-coloured robe, changing to black. These two 

 islands, in the course of an hour, floated out to the centre, and 

 then to the opposite bank. A' eight in the evening they had 

 changed their appearance but slightly, but the next morning 

 they had disappeared." It was observed that, as the falls 

 occurred, the exposed surface, sometimes more than too feet 

 across, was left red-hot. Sometimes a great mass would fall 

 fo.-ward like a wall ; at others it would simply collapse and slide 

 down, and again enormous boulders, as big as a house, singly 

 and in group;, would break from their fastenings, and, all 

 aglow, leap far out into the laUe. It is believed that this is 

 the first break-down of Kilauea that has taken place in the 

 presence of observers, those prior to 1S6S being before the 

 establishment of the Volcano House, and those of iS5S, 1S86, 

 and 1S91, and several minor ones, all having occurred at night 

 when no one was present. 



The additions to the Zoological Society's Gardens during 

 the past week include a Slender Loris {Loris gracilis) from 

 Ceylon, presented by Miss Grace Thomson ; two Wild Swine 

 {Siis sp. ?) from Turkish Arabia, presented by Mr. F. G. 

 Beville, H.B. M. Consul; three Agoutis {DasyprociA sp. ?) 

 and two Orange-winged Amazons [Chrysolis amazonica) horn 

 llie Island of Tob.ago, presented by the Hon. W. Low ; a Raven 

 (Corjus ,jrax\, European, presented by Mr. Ogilvie Grant ; a 

 Green T\ix\\e(Cheljiieviriiii;) from the West Indies, presented by 

 .Mr. E. Leach; a Japanese Teal {Qiier,;iii.iiila /ormosa) from 

 North-eastern Asia, purchased : a collection of Marine Fishes, 

 purchased ; two Shamas (Cittocincla tiiiicriiia) from India, 

 received in exchange ; a Braiilian Blue Grosbe.ik {Giiiraia 

 eyanta), and a Red-headed Marsh Bird (Aii^eldiis ruficapillus) 

 from Brazil, received in exchange ; and a Diana Monkey 

 (Cerccpilh^ciis liiitia) from West .\frica, deposited. 



OUR ASTRONOMICAL COLUMN. 



The IIarvkst Moon. — This year's Harvest Moon will be 

 exceptionally conspicuous. On the day of full moon, Septem- 

 ber 14, the ascending node of our satellite's orbit will be only 

 1° 35' from the vernal equinox. The inclination of the orbit 

 to the horizon will therefore he very nearly the same as if the 

 node were exactly at the equinox. Owing to this, the moon is 

 longer above the horizon than she is at other limes of the year. 

 On the aver.ige, the moon rises fifty-one minutes later every 

 night ; but for a (ew evenings before and after the coming full 

 moon, Ihc average interval is only about ten minutes. 



EcLll'.sE OF THE Moon.— A partial eclipse of the moon, 

 partly visible at Greenwich, will occur early on .Saturday 

 morning. The tirst contact with the penumbra takes place at 

 two o'clock in the morning, the first contact with the shadow 

 at 3h. 36m., and the middle of the eclipse happens at 4h. 32m. 

 The last contact with the shadow will occur at 5h. 27m. As 

 the moon sets shortly after, the last contact with the penumbra 

 will not be observable. Taking the moon's apparent diameter 

 as equal to I, the magnitudeof the eclipse =: o 225. 



M. Tisserand on SATELLiTE-OKDns. — M. Tiiscrand's 

 recent investigations on the satellite of Neptune have already 

 been referred to in these columns (vol. xlix. p. 543^ He ha^ 

 shown that the equatorial protuberance of Neptune causes the 



NO. I29S, VOL. 50] 



direction of the major axis of the orbit of the satellite to change, 

 and that the reaction of the satellite itself modifies the position 

 of the plane of the planet's equator. As the mass of the 

 satellite is comparatively small, the latter eft'ect can be 

 neglected for a considerable period of time. But when the differ- 

 ence of mass between a primary and its companion is not great, 

 the case is altered. In the Hullilin Astrotiomi^jiic for August, 

 M. Tisserand investigates the various conditions affecting the 

 secular displacements of the equator'of a planet and the satellite- 

 orbit. He cites the .\lgol system as a case in which the two 

 members — that is, the luminous star and the dark companion re- 

 volving round it — have comparable masses. The distance 

 separating the pair is also commensurate with their dimensions. 

 Under these condition^, the variations of the equator, and those 

 of the orbit of the satellite, can be treated at the same time. 

 The secular inequalities undergone by the equator and the orhit 

 doubtless cause the proportion of the bright star's disc eclipsed 

 by the dark companion to vary with the lapse of ages. .\ secular 

 change in the range of variability must result from this. Ob- 

 servations extendmg over a long interval of time should also 

 show changes in the periods of variables like Algol. M. Tis- 

 serand considers cases of this kind and develops the formul.^ 

 relating to them. The discussion of the formuire is reserved for 

 a future communication. 



The DisTRiKUTioN of Xeisul.i: and Star-Clusters. — 

 Mr. Sidney Waters has mapped the positions of thenebul.-v and 

 star.clusters — 7S40, in all — contained in the New General 

 Catalogue, and two excellent lithographed charts, given in the 

 number of Monthly Notices, R. A.S., just issued (vol. liv. No. 8), 

 show the results of his labours. The Milky Way is drawn upon 

 the charts, the portion for the northern heaven.s being taken 

 from Dr. Boeddicker's fine maps, while that in the southern 

 heavens is copied from the Craiiomctria Atj^entiita. Mr. 

 Waters designed the maps with two objects. First, to study 

 the distribution of nebula- and clusters of stars, and, secondly, 

 to guide astronomers engaged upon the observation of nebulas 

 to fields of research. Clusters are shown upon the charts by 

 means of red crosses, resolvable nebulre by red dots, and irre- 

 solvable ones by black dots. The distribution of these objects 

 is thus taken in at a glance. Whether, in the light of recent 

 research, it was desirable to continue to recognise thisdifterence 

 between nebulie is a matter of opinion ; one point in favour of 

 the distinction is that it was followed in similar maps drawn by 

 Mr. Waters and laid before the Royal Astronomical Society in 

 1873, so that the two sets are easily comparable. The present 

 charts show very clearly the peculiarities of the distribution of 

 clusters and nebul.v. Referring to the former, Mr. Waters 

 says: "It is striking to note the fidelity with which they 

 follow not only the main track of the Milky Way but also its 

 convolutions and streams. They appear in many parts to seek 

 out the denser regions, and to avoid with an equal persistence 

 the dark spaces. " As to nebul.-e, we re-ad (and the maps bear 

 out the remarks): " .\ proportionate scattering of resolvabli- 

 nebuke follow the others throughout the charts, showing tin 

 they are probably intermixed, and that theresolvability of many 

 of them must not necessarily be regarded as a criteiion of their 

 distance. The remarkable avoidance of the nebul.-c of the 

 galaxy, although in some points reaching up to and encroaching 

 upon its edges, is equally significant with the coincidence of the 

 clusters with its main track. " It is pointed out that the exceed 

 ing nearness to one another of very many of the nel)ul.x' suggest^ 

 the probability of physical connection analogous to that ol 

 double stars, hence long- continued observations may lead to the 

 detection of similar orbital motions. (Uher fields of research 

 are suggested by the charts, and by exploring them new light 

 will certainly be thrown upon the structure of the sidereal 

 universe. 



THE AMERICAN ASSOCIATION FOR Till 

 ADVANCEMENT OF SCIENCE. 



i\ (H'.NER.VL account of the recent meeting of the American 

 '' Association for the Advancement of Science was con- 

 tiibuted to our last issue by Dr. \\'. H. Hale. We are now 

 able to give a few extracts from presidential addresses, together 

 with descriptions of some ol the papers re.ad before the 

 different sections. 



In the course of his reply to Ihe address of welcome to 



