NA TURE 



[November 25, 1897 



index to current technical literature. The issue of a distinctly 

 European edition of the magazine was commenced last month, 

 and we are confident that it will meet with as much success here 

 as it has in the United States. 



The additions to the Zoological Society's Gardens during the 

 past week include a Macaque Monkey {Macacus cynomolgus) 

 from India, presented by Mr. F. Greswolde-Williams ; a 

 Suakin Gazelle {Gazella brookii) from Abyssinia, presented by 

 Dr. L. de Gebert ; two Ring-necked Parrakeets (Palaornis 

 torqtiatus) from India, presented by Mrs. G. F. Cooper ; a 

 Macaque Monkey {Macacus cynomolgus, albino) from Manilla, 

 presented by Mr. James Coombs ; two Double-spurred Fran- 

 colins [Francolinus bicalcaratus) from West Africa, four Rosy 

 Bullfinches {Erythrospiza gilhaginea), bred in England, pre- 

 sented by Mr. E. G. B. Meade-Waldo ; two Herring Gulls 

 (Lams argentatus), British, presented by Mr. T. Hope Robin- 

 son ; two Rhomb-marked Snakes (Triinerorhtnus rhombealus), 



two Snakes {Chlorophis hoplogasler), a Puff Adder [Bills 



arielans) from South Africa, presented by Mr. J. E. Matcham ; 

 a Ring-tailed Lemur {Lemur calla, 9 ) from Madagascar, a 

 Macaque Monkey [Macacus cynomolgus) from India, deposited ; 

 six Rosy-faced Love Birds [Agapornls roseicollis) from South 

 Africa, a Malaccan Parrakeet {Pahcornis longicauda) from 

 Malacca, four Siskins {Chrysomitris spinus), four Lesser Red- 

 polls {Linota rufescens), British, a Bridled Wallaby [Onychogale 

 frenata) from Australia, a Loggerhead TyxxxXe [Thalassochelys 

 caretta) from the Mediterranean, purchased. 



OUR ASTRONOMICAL COLUMN. 



The November Meteor Swarms.— Up to the present 

 time we have not received any news that the Leonids were more 

 abundant this year than last. Indeed, bad weather seems to 

 have universally prevailed about the time of observation. At 

 the Paris Observatory five observers only noted twenty meteors, 

 while M. Hansky, at the Meudon Observatory, saw in all seven, 

 four of which were Leonids. M. Janssen, in consequence of the 

 exceedingly bad weather experienced in Western Europe, tele- 

 graphed to San Francisco to inquire whether a more brilliant 

 display had been noted there. The answer he received was to 

 the effect that nothing more than the ordinary shower was 

 observed. Perhaps, however, observers may be (or may have 

 been) more fortunate with the Andromedes, which are expected 

 between the 23rd and 27th of this month. This swarm is also 

 of considerable strength, and should be more than usually active 

 Its period of revolution being six and a half years, and the last 

 maximum having occurred on November 23, 1892, we expect 

 the shower this month to be above the ordinary yearly display. 

 There are several points about the Andromedes that are of peculiai 

 interest. One of these is that the orbit in which they move is 

 very similar to that of the comet Biela ; in fact, the bodies which 

 produce the phenomena of shooting stars may be none other 

 than the component parts of this comet. In the years 1872 and 

 1885 the maximum display occurred on the 27th of the month, 

 but at the following expected shower it took place on the 23rd. 

 This difference is explained, according to Bredichin, by the per- 

 turbatory effects due to the proximity of the planet Jupiter, thus 

 causing the node to recede 4°. The radiant point of this swarm 

 (25° -t- 43°) has a large northern declination, which renders it 

 always above the horizon. The meteors themselves are different 

 from the Leonids in that they move more slowly, and are of a 

 yellowish tinge. 



In the note under this heading, that appeared last week, it 

 should have been mentioned that the observations recorded were 

 made by Dr. W. J. S. Lockyer at the Solar Physics Observatory, 

 South Kensington. 



In another part of this journal Mr. Denning summarises the 



results of this year's Leonid display. 



Current Astronomical Articles. — M. Gaston Armelin 

 contributes an interesting article on that curious variable Mira Ceti 

 to La Nature for November (No. 1274). After a brief historical 

 summary the writer describes some theories current to-day, 

 and points out the variations in the time of maxima observed 



NO. 1465, VOL. 57] 



of late J ears, and their consequent suggested explanations. —The 

 bulletin of the SociiU Astronomiqtte de France for the same month 

 contains, among other interesting matter, a drawing of comet 

 Perrine as observed at the observatory of Juvisy. M. Camille 

 Flammarion deals with the Leonid swarm of meteors. The 

 number contains several contributions of planetary notes. -r-In 

 the October number of Himniel und Erde, a brief account is 

 given of the present state of the proposed large Potsdam re- 

 fractor. There seems to have been some difficulty about the optical 

 parts, so that it has been decided to assume that the aperture will 

 be 80 cm., and commence at once with the construction of the 

 instrument and a suitable dome. This instrument when finished 

 will be then the largest in Europe, the aperture being nearly 

 thirty-two inches. This article contains the results of many in- 

 vestigations on the absorption properties of different thicknesses 

 and kinds of glass. 



Comet Perrine (October 16). — This comet is gradually 

 becoming fainter, but a continuation of the ephemeris for the 

 current week will perhaps prove useful : — 



I2h. Berlin M.T. 



1897. 



R.A. 



Decl. 



log r. 



log A. 



Br. 



Nov. 25 ... 18 16 49 ... -i-59 24-6 



26 ... 15 45 ... 58 44 "8 ... o'i376 ... 0-0278 ... 07 



27 ... 14 47 ... 58 6-4 



28 ... 13 54 ... 57 29-3 ... 0-1366 ... 0-0370 ... 07 



29 .. 13 6... 5653-4 



30 ... 12 23 ... 56 188 ... 0-1357 ... o 0459 ... 07 

 Dec. I ... II 43 ... 55 45-5 



2... II 7 ••• 55 i3"5 •■• 0-1351 ... 0-0546 ... 0-7 



3 ... 18 10 34 ... -F54 42-4 



Rev. Dr. Searle has resigned the directorship of the 

 astronomical observatory of the Catholic University of America. 

 His place will be taken by Mr. Alfred Doolittle. 



THEORY OF THE MOTION OF THE MOON} 



/^F the lunar theories hitherto completed the two greatest are 

 ^-^ undoubtedly those of Hansen and Delaunay. The former 

 has for its chief object the formation of tables : the inconvenience 

 of slowly converging series is avoided by using numerical values 

 throughout ; and the problem solved is the one actually presented 

 by nature, every known cause of disturbance being allowed for. 

 It suffers, however, under the disadvantage that there are no 

 means of correcting the results for any change in the values of 

 the constants that observation may demand. This drawback 

 was avoided by Delaunay, but only at (he expense of still greater 

 evils from the point of view of the making of an ephemeris ; for 

 owing to the slow convergence of certain series, twenty years' 

 labour did not suffice to give sufficiently approximate results ; 

 moreover, the problem had to be considerably modified from 

 the circumstances of nature, in order to achieve a result within 

 even so long a time. 



The memoir that Dr. Brown has lately presented to the Royal 

 Astronomical Society, forms the first part of a fre.sh attempt to 

 calculate the motion of our satellite. All Delaunay's modifica- 

 tions of the problem are adopted : that is to say, the sun and 

 earth are supposed centrobaric, the mass of the moon is neglected, 

 as is also the action of the planets, and the true mass of the sun 

 is increased by that of the earth. The calculation of the effect 

 of the attraction of the planets and of the protuberant parts of 

 the earth's equator will follow when the modified problem is 

 solved. The solution can also be easily modified so as to allow 

 for the greater part of the effect of the remaining modifications, 

 and the outstanding error Dr. Brown has shown to be insensible 

 to observation ; but it is, however, far larger than the minute 

 fraction of a second to which his calculations are pushed. 



Dr. Brown's theory resembles Delaunay's in being algebraical 

 with, however, one important exception : the ratio of the mean 

 motions is replaced by its numerical value. By this means the 

 slowly converging series that occur in Delaunay's theory are 

 avoided ; and no admissible correction of the value of the above 

 ratio can introduce any change in the results that would Le 

 sensible to observation. This modification in the form, combined 



1 " Theory of the Motion of the Moon." Containing a new calculation of 

 the e.xpressions for the coordinates of the Moon in terms of the time." By 

 Ernest W. Brown, M.A., Sc.D. (Reprinttd frcm the Memoirs of the Royal 

 Astronomical Society, vol. liii.) 



