February 2, 1905 J 



NA TURE 



329 



JuriTER's Sixth Satellite. — A further telegram respect- 

 ing the recently discovered sixth satellite of Jupiter has 

 been received from the Kiel Centralstelle. It contains a 

 statement from Prof. Perrine that the object discovered by 

 him is not identical with Prof. Wolf's minor planet 

 1905 P.V. The position of the satellite on January 17 at 

 8h. 44.3m. (Lick M.T.) was R.A. = ih. 21m. 8s., 

 dec. = +7° 27'. 



.A later telegram than the above, published in a supple- 

 ment to No. 3990 of the Astronomische Nachrichten, 

 states that Prof. Perrine observed the satellite on January 

 17.702 (G.M.T.), and found that its position with reference 

 to Jupiter was 266° and its distance 36'. 



EpiiEMERis FOR CoMET 1904 e. — The following is the 

 latter part of a daily ephemeris for comet 1904 e (Borrelly) 

 published by Herr M. Ebell in No. 39S9 of the Astro- 

 nomische Nachrichten. 



1905 a (true) S (true) log; log li Bright- 



Feb. I ... 2 9 8 ... + 15 17 ... 02092 ... 0-1501 .. 0-58 

 2 ... 2117 ... +15 54 

 1 . . 2 13 6 ... +16 31 

 4 ... 2 15 7 ... +17 7 

 _ 5 ... 2 17 8 ... +17 43 ... 0-2133 ■■ o'i638 ■■■ 0-54 

 Brightness at tiine of discovery = i.o ( = mag. 10. o). 



From the above it will be seen that the comet is now 

 travelling in a north-easterly direction through the con- 

 stellation Aries, and is observable — although very faint — 

 between sunset and midnight. 



Solar Eclipse Problems. — In an address read at the 

 International Congress of Arts and Sciences, held at St. 

 Louis in September, Prof. Perrine enumerated and dis- 

 cussed a number of the outstanding problems which still 

 confront solar eclipse observers. 



The first problem mentioned was that relating to the 

 existence of an intra-mercurial planet, and Prof. Perrine 

 states that this year's eclipse ought to settle the problem 

 so far as the existence of a body brighter than the tenth 

 magnitude is concerned. Such a body would not be above 

 12 or 15 miles in diameter, and it would take about a 

 million such to account for the anomalies in the motion 

 of Mercury. 



The movements and velocities of coronal matter are most 

 important problems which should be settled, and, as 

 stations situated so far apart as Labrador and Egypt may 

 be utilised during the coming eclipse, this should offer 

 ail exceptional opportunity of solving the problem, because 

 of the length of time between the passing of the shadow 

 at these places. Prof. Perrine suggests the employment 

 of cameras having focal lengths of 40 or 50 feet and 

 pointed directly at the sun, or, where the atmospheric con- 

 ditions are favourable, longer cameras, mounted horizon- 

 tally, might be used. The rotational velocity of the corona 

 as regards that of the sun's surface is another problem 

 which he discusses. Finally, he points out the urgent need 

 for a number of well-equipped and well-organised expe- 

 ditions, and suggests that the interchange of plans and 

 ideas before the eclipse takes place might lead to results 

 of greater value being obtained. 



The Conditions in the Solar Atmosphere during 

 1900-1. — An interesting discussion of the conditions 

 obtaining in the solar atmosphere during the minimum 

 epoch of 1900-1, as indicated by the author's eclipse 

 photographs taken in Spain and Sumatra, is given in the 

 January number of the Bulletin de la Socii'tc dc France by 

 M. N. Donitch, of St. Petersburg. He discusses in turn 

 the spectra of the chromosphere, the prominences and the 

 corona, the form of the corona, and the solar repulsion 

 theory of Prof. Bredichin as applied to the latter. 



In discussing the spectrum of the chromosphere, he refers 

 to Sir Norman Lockyer's eclipse results, and, in directing 

 special attention to the lines at A.A. 5317.7 and 4233.8 

 (Donitch), he states that his results as to the non-agree- 

 ment of these with the monochromatic coronal radiations 

 incontestably confirm the conclusions arrived at from the 

 English observations. 



The spectra obtained by M. Donitch show that the 

 prominences may be divided into two types, one composed 

 entirely of calcium vapours, the second containing in 

 addition hydrogen and helium. 



NO. 1840, VOL. 7 l] 



Triangulation of the Pleiahes Stars. — An important 

 addition to the data concerning the positions, the inter- 

 mutual distances, and the movements of the Pleiades stars 

 is contained in parts vi. and vii., vol. i., of the Transac- 

 tions of the .Astronomical Observatory of Yale University. 



During 18S4-6 the director. Dr. Elkin, made a series 

 of heliometer observations for the triangulation of the 

 Pleiades, and published the results in part i. of the same 

 volume of the Transactions. Since then, however, a new 

 source of systematic error affecting such results has been 

 discovered, and Dr. Elkin has, therefore, re-reduced his 

 observations. The final values are given in part vi., and 

 are therein compared with the similar results obtained at 

 Konigsberg in 1840 and those obtained during the more 

 recent triangulation carried out at ^'ale. The results of 

 these comparisons indicate a motion, in regard to the rest 

 of the grcup, of 9 out of the 58 stars common to the 

 three researches ; the apparent displacements determined 

 from the comparison of the Konigsberg and Yale results 

 are shown on a chart accompanying the present paper. 



Part vii. of the publication contains an account of the 

 second triangulation carried out at Yale by Mr. Mason F. 

 -Smith during the winters of 1900-1 and 1901-2, and 

 shows the complete reduction of the observations, together 

 with a final table in which the places of 58 Pleiades stars, 

 for 1885.0, are given with the precession and secular 

 variation values for each. 



A Bright Meteor. — Mr. J. Ryan, writing from the 

 Manor House, Kensal Green, N.W., states that he 

 observed a very brilliant meteor at about 11.58 on the 

 night of January 27. The meteor appeared about three 

 degrees below Orionis as bright as a star of the first 

 magnitude ; it travelled slowly in a path nearly parallel to 

 a line joining k and ^ Orionis, increasing in size until it 

 burst into a green ball when below 3 Orionis, and faded. 

 The complete path was traversed in about 8 seconds. 



THE GENERAL MOTION OF CLOUDS. 

 'T'HE issue of the Quarterly Journal of the Royal Meteor- 

 ological Society for October, 1904, contains a trans- 

 lation of the report on the international observations of 

 clouds presented by Prof. H. H. Hildebrandsson to the 

 Permanent International Committee during its session 

 at Southport in 1903. It is not too much to say that 

 this report is one of the most important contributions to 

 our knowledge of the physics of the atmosphere which 

 the last twenty-five years have brought forth, and the 

 Royal Meteorological Society has rendered a substantial 

 service by making the report accessible to English readers. 



Our knowledge, from direct observations, of the average 

 motion of the air over the greater part of the earth's 

 surface has been in a sense complete for a considerable 

 number of years, but of the currents in the upper air we 

 have until recently had little or no direct information, 

 and all schemes of a general circulation of the atmosphere 

 as a whole have had to substitute hypothesis for fact in 

 dealing with this part of the subject. It therefore became 

 of the highest irhportance to see whether any direct 

 evidence could be obtained on this point. The most obvious 

 method of attacking the problem consisted in observing 

 the direction and speed of drift of dust or water 

 particles suspended in the atmosphere. Dust particles are 

 seldom sufficiently numerous in the upper air to be of use 

 in this connection, but clouds occur in all parts of the 

 world, and their observation is comparatively easy. Even 

 this method, however, has its limitations. Observations 

 are clearly impossible on cloudless days, and. it also fre- 

 quently happens that the upper clouds are obscured by 

 lower cloud forms. 



To obtain any general results observations from every 

 part of the earth's surface were essential, and to secure 

 these the ponderous machinery of international cooperation 

 had to he called into play. In the year 187S a request 

 was addressed to the Permanent International Committee 

 to organise a comprehensive system of cloud observations. 

 After some preliminary consultations a scheme, in which 

 cloud forms were divided into two classes, viz. upper and 

 lower clouds, was adopted, and observations on this plan 



