August 24, 1893] 



NATURE 



401 



with the solution of the pure crystallised salt. Recrystallisation 

 of the whole is attended with a considerable loss. The crystals 

 are quite permanent, however, when stored in dry bottles with 

 well-fitting stoppers. 



Notes from the Marine Biological Station, Plymouth. — Last 

 week's captures include the Anthozoan Gephyra Dohrnii, the 

 .^olid Amphorina cceruUa, the Cirrhipede Scalpdlum vulgare, 

 and the Brachyura Ebalia tumefcuta and Achatis Cranchii. 

 The floating fauna continues to be rich in trochophore larvae of 

 various types, as recently recorded ; the larva of Polygordius 

 was last week taken in addition. Among Protozoa, Noctihica 

 has become more plentiful ; but the week has been especially 

 marked by the presence of Radiolaria of several species in 

 numbers altogether unprecedented in our experience. Other 

 signs of an Atlantic element in the floating fauna of late are 

 furnished by the continued abundance of the Siphonophore 

 Muggiaa atlantica, both colonies, eudoxomes and larvae, and 

 by the capture of two specimens, sexually mature, of Doliolum 

 Trilonis. The Hydroids Aglaophenia pluma and myriophyllum 

 and the Nudibranch /Eolidiella Aldtri are now breeding. 



The additions to the Zoological Society's Gardens during 

 the past week include a Mona Monkey {Cercopitkectts mono) 

 from West Africa, presented by the Misses Price ; a Yellow- 

 cheeked Lemur {Ltmur xanthromystax) from Madagascar, 

 presented by Miss Annie Gervers ; a Bonnet Monkey {Macacus 

 sinkus) from India, presented by Mr. J. W. Harris ; a Short- 

 toed Eagle (Circaelus galHctis) from Morocco, and six Little 

 Bitterns {ArdMa minula) from Europe, presented by Lord 

 Liiford ; a Black-headed Gull (Larus ridibimdus) from Brit. 

 Isles, presented by Mrs. H. S. Wardrop ; an Indian Kite 

 (Mdvus govinda) from Eastern Asia, presented by Mr. A. 



Savory ; four Tortoises ( ) from Formosa, presented by 



Mr. P. Aug. Hoist ; a Golden Cat (Felts moormensis) from 

 Sumatra, a Slender-billed Cockatoo {Licmetis tenuirostris) from 

 Sou h Australia, and six Avocets {Recurvirostra avocetta) from 

 Holland, deposited ; six Avocets {Rtcurvirostra avocetta) from 

 Holland, a Common Tern {Sterna hirundo) from Holland, a 



Japanese Ape (Macacus speciosus) from Japan, and a 



Hawk Eagle {Spizactus ) from India, purchased. 



OUR ASTRONOMICAL COLUMN. 



, The Cordoba Durchmusterung.— Mr. John Thome, the 

 ; Director of the National Argentine Observatory, is to be con- 

 'gratulated upon the publication of the Cordoba Durchmuster- 

 ung Catalogue, containing the brightness and position of every 

 , fixed star down to the tenth magnitude comprised in the belt of 

 the heavens between 22° and 32° of south declination. The 

 ■results are a continuation of the Durchmusterungs of Argelander 

 land Schonfeldt from their southern limit. In the present 

 volume 179,800 stars are catalogued, but altogether the places 

 of 340.380 stars have been determined down to - 42°. The ob- 

 servations for this great catalogue were begun in 1885 and ended 

 jearly in 1891. They reach the enormous nujnber of i,loS,6oo, 

 and were made entirely by Mr. Thome and Mr. R. H. Tucker. 

 The area over which the observations have extended is 6075 

 idegrees of a great circle, hence the mean density of stars is 

 l56-2 stars per square degree. The corresponding mean density 

 ,for Argelander is 15-2, and for Schonfeldt 185. The density 

 varies considerably, however, in different parts of the sky, and 

 ranges from 70 to 160 stars per square degree in the Milky Way. 

 Mr. Thome says that a series of twelve maps, each embracing 

 I'.wo hours of right ascension and twenty degrees in declination, 

 -las been constructed upon the scale adopted by Argelander, and 

 jivill be issued during next year with the second volume of the 

 Catalogue, containing stars within the belt from 32' to 42' south 

 declination. The construction of these maps, and the prepara- 

 ; ion of a catalogue like that of which the first part has just 

 jeached us, involves an enormous amount of labour. Indeed, 

 t is difficult to understand how, amidst the vicissitudes to which 



NO. 1243, VOL. 48! 



an observatory in the Argentine Republic must be subject, and 

 with such a meagre staff as that under Mr. Thome's direction, 

 it has been possible to do so much excellent work. 



The RoRDAME-QuilNlsSEr Comet. — On July 11 the Ror- 

 dame-Quenisset comet [b 1893) was photographed at Goodsell 

 Observatory, and a fine photogravure reproduction of one of 

 the views forms the frontispiece to the August number of 

 Astronomy and Astro- Physics. In a letter that appears in the 

 same journal. Prof. J. E. Keeler describes the spectroscopic obser- 

 vations of the comet made at Alleghany Observatory. On July 

 10 the three usual carbon bands were seen, connected by a narrow 

 continuous spectrum from the nucleus. Each band appeared 

 to terminate sharply on its less refrangible side, where also the 

 brightness was greatest. No direct comparison of spectra could 

 then be made, so the positions of the bands were estimated. 

 A photograph of the comet spectrum in juxtaposition with the 

 solar spectrum obtained from the moon was procured on July 19. 

 Upon the photograph could be seen a hazy band at \ 472 and 

 another terminated by a line on the less refrangible side at A. 388, 

 and fading away towards the more refrangible end of the 

 spectrum. Between these two bands others were susjiected, but 

 could not be made out with sufficient accuracy f. r a determina- 

 tion of wavelength. A comparison of the spectrum uf the 

 comet with that of a spirit lamp on July 20 showed that the 

 bands were coincident in the two spectra. The brightest comet 

 band — that in the green — appeared to have a second maximum 

 coincident with the second maximum of the corresponding carbon 

 fluting 



A Simple Equatorial Mounting. — M. J. Jarson describes 

 in V Astronomie for August a simple, if nut new, means by 

 which small telescopes can be moved equatorially, thus per- 

 mitting an observer to keep objects in the field of view with- 

 out constantly moving the telescope in altitude and azimuth. 

 Applying this method, for instance, to a small telescope 

 mounted on a small vertical tube, tripod fashion, such as those 

 generally used at seaside resorts, the following account may show 

 the simplicity of the arrangement. On the stand of the tele- 

 scope a bar of wood or of iron is fixed horizontally, in which 

 is a hole sufficiently large to pass a cord. The podtion of the 

 hole is determined by the rule that the line joining the centre 

 of motion of the telescope in declination to this hole makes an 

 angle with the horizontal bar equal to the latitude of the place 

 of observation. By connecting the object-glass end of the tele- 

 scope to this hole, by means of a chain or cord, any celestial 

 object can be followed in the heavens by simply keeping the 

 cord tight and moving the telescope. A weight fastened to the 

 eye end secures the tightness of the cord. The telescope will 

 then describe an arc of a circle in the heavens, and not a 

 straight line as formerly. For different objects it is obvious 

 that one must vary the length of the cord ; but for making pro- 

 longed studies of any particular one possessors of small instru- 

 ments will find this a most useful arrangement. 



A Remarkable Source of Error. — Dr. E. Von Rebeur- 

 Paschwitz, in No. 3177 oi \\i^ Astronomische Nachtichten,-^w\i- 

 lishes some interesting curves traced by a horizontal pendulum 

 during the prevalence of certain slight earth tremors occurring 

 on different occasions and at different places. Traced photo- 

 graphically on sensitive plates moving with a velocity of twenty- 

 four inches per minute, these tremors show a stiiking similarity 

 to those observed by Prof. Milne in Japan. It appears that the 

 surface of the earth is occasionally subjected to wave motions 

 analogous to those disturbing a sheet of water, and often per- 

 sisting with great regularity for several hours. 'Their connection 

 with steep barometric gradients is probable, although that does 

 not appear to be the only condition. In auy case, the tremors 

 appear in the presence of strong winds, at least in the neigh- 

 bouring country, and they travel with at least the velocity of 

 2 km. per second. The influence of these trtmors upon obser- 

 vations of polar distances, and upon spectro- photographic work, 

 is sufficiently obvious to render it desirable that all ob.eivatories 

 should be fitted with automatic instruments for registering these 

 disturbances, and arrangements should be made for their study 

 and comparison. 



The Apex of the Sun's Way.— In a letter to the editor 

 of the Bulletin Aslronomique, Prof. H. G. van de Sande 

 Bakhuyzen says that he has determined the apex of the move- 

 ment of our system from all Bradley's stars of which the dis- 

 tances from the pole of the Milky Way are less than 50°. In 



