478 



NATURE 



\_Sept. 15, 1 88 1 



f)r the mean value gh. 5Sm. 35-25., but when the individual 

 observations are compared with it, a well-marked maximum 

 displacement of the centre of the spot, to the amount of i"-4, 

 is exhibited, apparently indicating that it gradually oscillated to 

 thi^ extent in longitude, which on the urface of Jupiter corre- 

 sponds to about 3200 miles. The observations however may be 

 well represented by making the period of rotation a function of 

 the time; thus the period gh. 55m. 33-25. -F o-l8s. V is found 

 to satisfy all the measures with a mean maximum error of 0"-$ : 

 the zero-epoch being September 25, 1879, and t the number of 

 days after that date. The mean-rotation period derived from 

 observations of polar spots is gh. 55m. 35-ls., that deduced 

 from the small spots indicating an average displacement during 

 two months of 2", or about 4600 miles. The rotation re-uliing 

 from the observations of equatorial spots is gh. 50m. g'Ss. with 

 uniform motion. Prof. Hough states that the actual size of the 

 cTeat red spot, as seen with the Chicago telescope (iSJ inches 

 aperture) is — length, 29,600 miles; breadth, 8300 miles ; and he 

 remarks that smaller telescopes make the approximate Imgth 

 considerably le s than the real value. 



The nebula near Merope in the Pleiades, of which so much 

 has been written, was not seen with the Chicago refractor in 

 1879, but as so many observers have de-cribed it. Prof. Houjh, 

 in conjunclion with Mr. S. W. Burnham, made a thorou,di exami- 

 nation of the locality, with the result that they sati lied them- 

 ! elves that "the nebula did not exist, but that the appear- 

 ance described by different astronomers was wholly an optical 

 illusion, due to the glow from Merope and neighbouring 

 stars." This opinion will probably be disputed in many 

 ijuarters. 



The Washburn Observatory, Wisconsin. — No. i of 

 " Contributi ns from the Washburn Observatory, of the Uni- 

 versity of Wisconsin," has been received. The establishment is 

 under the direction of Prof. Edward S. Holden, late of the 

 Naval Observatory, Washington. Work was commenced in the 

 latter part of April in the present year, with the Clark refractor 

 of 15-56 inches aperture, and Prof. Holden has had the good 

 fortune to secure the co-operation of that emin nt observer, Mr. 

 .S. W. Burnham, who left Chicag:) at the beginning of April 

 to accept a post in Washburn Observatory, and although the 

 publication to which we refer is dated May 31, some five weeks 

 after the commencement of operations, thirty-four new double- 

 stars had been detected and measured by Mr. Burnham, and a 

 number of other dou' les, discovered in the course of zone-obser- 

 vations in which Prof. Holden took part, were also measured. 

 In addition we have a list of new nebulce detected in the zone- 

 observations, several of which appear to deserve special attention. 

 On Maya, in R.A. l8h. Sm. N.P.D., 108" 20', a void space 

 was remarked in the Milky Way ; it is thus described : "This is 

 a black circular hole (10') in the Milky Way. The stars around 

 it are exce sively crowded, and inside there are but two stars, 

 one 10 mag., the other very small." 



The number of newly- discovered objects — double stars and 

 nebula; — of which we have the particidars in this first " Contri- 

 lu'ion " from the Washburn Observatory, is quite extraordinary, 

 considering the few weeks over which observations have ex- 

 tended. We wish continued success 'to the Observatory of the 

 University of Wisconsin. 



Schaeberle's Comet. — The following meridian observations 

 S.P. of Comet c 1S81, made with the transit-circle at the Rad- 

 cliffe Observatory, Oxford, have been communicated by Mr. F. 

 J. Stone, the Radcliffe observer. The N.P.D. is uncorrected 

 for parallax. 



G.M.T. R.A 



h. m. s. 



Tuly 31. 9 54 47'5 



(a) Aug. 2, 9 56 28-0 



4, 9 59 56-5 



6, 10 6 1-3 



10, 10 29 50-1 



{b) 19, 12 35 2-4 



(ij) Comet very faint. Only an approximate observation. 



(/») Much brighter. Observation good. 



Encke's Comet. — The early observations of this body point 

 to a negative correction of the mean anomaly to the extent of 3', 

 which corresponds to a retardation in the time of perihelion 

 passage of about C^-ieg The perturbations from the action of 

 Jupiter during the last revolution have been much greater 

 than between 1875 and 1878, in which latter year the necessary 



N.P.D. 



6 28 21-6 ... 4°4 3 46-1 



6 37 55-6 -.. 42 57 (36) 



6 49 17-7 ... 41 47 I3"3 



7 3 i6-6 ... 40 35 47'9 

 7 42 55 6 ... 38 21 31-6 



10 23 57-4 ... 40 44 50-7 



correction to the mean anomaly given by the calculations of the 

 late Dr. von A^ten, was about one-third as great, but in the 

 same direction. The work of his successor, Dr. O. Backlund of 

 Pullcowa, has been executed with a most thorough determination 

 of the planetary p-rturbatious, which is extended to the prepara- 

 tion of the ephemeris. 



The first glin pe of the comet, so far as we know at present, 

 was obtained by Dr. Hartwig and Prof. Winnecke with the six- 

 inch cmet-seeker at the Observatory of Strassburg on August 20. 

 Five days later it was clearly seen in the same instrument as a 

 nebulosity 4' in diameter. 



Elongations of MiM.is. — The following Greenwich times 

 of apparent preceding elongations of this difficult object depend 

 upon the same elements as previously used in this column : — 



Sept. 19 at 15 36 

 20 at 14 13 



Sept. 21 at 12 50 

 22 at II 27 



Sept. 23 at ID 4 

 24 at 8 41 



GEOGRAPHICAL NOTES 



The International Polar Conference, which was held last 

 year at Berne, and the previous year at Hamburg, met last 

 month at St. Petersburg. The object of this Conference is 

 ihe organisation of a series of stations around the Polar area 

 for the continuous prosecution of scientific observations. Since 

 its last meeting it has lost Eieut. Weyprecht, who was ihe 

 originator of the idea of such a scheme. Delegates were pre- 

 sent from all the leading European States except Engl.md, and 

 from the United States of America. The fir.st subject discussed 

 was the time at which observatie^ns should be taken, and their 

 frequency. Observations will begin for all the expeditions in 

 the Polar regions, as also for observations in the temperate zones, 

 as soon a? possible after August i, 1882, and will finish as close 

 as possible to September I, 1883. All the meteorological and 

 mngnetical phenomena will be observed hourly during all this 

 time ; and, besides, there will be taken on the 1st and 15th of 

 each month magnetic observations every five minutes for 

 twenty-four hours, and every twenty seconds during an hour of 

 the day fixed on i 1 advance, and that everywhere after the mean 

 time of Gottingen. Theso latter observations have for their 

 special end to obtain a perfect knowledge of perturbations or 

 mngnetic storms, and their connection with the .aurora borealis. 

 On the ba is of a programme of observations to be made, already 

 elaborated by the Hamburg Conference, the obligatory meteoro- 

 logical observations were discussed — i.e , observations which all 

 the stations must make in order to in.sure the scientific success of 

 the enterprise. The result of the discussion was the fixing of 

 the principles, and in part also of the melhods and instraments 

 of observation, to insure the accuracy and comparability of the 

 meteorological observations to be made. Happily the Conference 

 numbers among its members several distinguished men of science, 

 who have acquired in former expeditijns in the Polar regions 

 very great experience of the difficulties to be met with in taking 

 observations, who were atile to give advice useful in obviating 

 beforehand those obstacles, by the arrangement of the ins'ru- 

 ments, and by the method of taking ob ervations. One day 

 was devoted by the Conference to visiting the celebrated me- 

 teorological and magnetic observatory of Pavlovsk, and discussing 

 there Ihe choice of the best apparatus. The members visited in 

 detail the provisional installations which have been made at 

 the observatory for inspecting the magnetic instruments intended 

 for the Russian expedition to the month of the Lena. At the 

 third sitting of the Conference, the magnetic observations were 

 discussed : these also meet with difficul'ies unknown in tem- 

 perate zones. It is not only the great cold, but also the feeble- 

 ness of the horiz' ntal intensity of terrestrial magnetism, as also 

 the frequency and greatness of the perturbations, which render 

 observations very ciiflicult and delicate. At the fourth meeting 

 the Conference was occupied with observations on the aurora 

 borealis, and w ith the question of facultative observations, those 

 which are recommended to the expeditions, without being con- 

 sidered indispensable — as observations on the temperature of the 

 soil, evaporation, terrestrial galvanic currents, atmospheric elec- 

 tricity, &c. The conference, among other things, decided to 

 apjily to different institutes to assure their co-operation, and to 

 request magneiic observatories in the temperate zones, especially 

 those in the southern henvsi here, to participate in the simul- 

 taneous obsei vations, as also to ask the directors of the tele- 

 graphs of different countries to study more accurately terrestrial 



