1 1' I V. 1004. 



KNOWLEDGE & SCIENTIFIC NEWS. 



159 



suggested the enquiry as to the presence of titanium ami its 

 usual associate, vanadium, in stars of tlie third type on 

 account of the importance of those two elements in suiispot 

 spectra. 



■>r >r -)i- 



The Fifth Satellite of Jupiter. 



Miss E. E. Dobbin, whilst a student at the \erkes Observa- 

 tory in the summer of tqo2, undertook, at the request of 

 Professor Barnard, an investigation of the relative worth of 

 the orbits deduced for the fifth satellite of Jupiter by Or. 

 Cohn and M. Tisserand. Later, she undertook a complete 

 discussion of the problem, using only the observations of 

 Professor Barnard, in order to secure greater homogeneity. 

 The observations ranged from 1892 to H)0 5 inclusive, and her 

 discussion gives the following elements of the orbit : — 



(n) = 47"-96i 



(c) = 0-00308 



rfP = 2'''42g daily, or 887"'20 yearly. 

 I' = 227°-IO, !■—/,= KJi^'So 

 « = 722"63i6 daily 

 The most noticeable feature of these results is the smalliiefs 

 of the eccentricity as compared with that obtained by Dr. t'ohn 

 and M. Tisserand. Miss Dobbin is doubtful wluthcr the 

 change is real, and denotes a progressive perturbation wliich 

 will end in reducing the ellipse to a perfect circle, or is an 

 accidental one, and the question can only be decided after 

 another decade of observation or more. The satellite was 

 noted to be ahead of its ephemeris place in i<)02 and njoj. 

 This was due to the initial value of the longitutle of the node 

 being too small by o''7, or i''4, by which amoiml thi' orbit 

 should be moved forward. 



* * * 



Orbit and Spectrum of Delta Orionis. 



About four years ago M. Deslandres found that Delta 

 Orionis varied in its velocity in the line of sight, or, to use a 

 shorter phrase suggested by Dr. Hartmann, was an "oscillat- 

 ing" star. M. Deslandres deduced a period for it of i-gz days, 

 and a very eccentric orbit. The star was then placed on the 

 observing list at Potsdam, and Dr. Hartmann, having obtained 

 more than 40 plates of its spectrum, has carried out a new 

 discussion of its orbit ; for which he finds the period, 5 days 

 17 hours 34 minutes 48 seconds + 17 seconds, and an eccen- 

 tricity, O' 10334. In other words, the orbit is nearly circular. 

 But the striking discovery lies here: whilst the lines m general 

 are characteristically hazy, and show periodical displacements, 

 one line, the K line of calcium, though always exceedingly 

 weak, is always narrow and sharp, ctmi takes no part in the 

 periodic liisjtlacemeiit shou-n hy the other lines. Dr. Hartmann 

 concludes that this K line cannot be due to the spectrum of 

 the fainter component of the star, but that a cloud of calcium 

 vapour must lie between us and Delta Orionis, producing this 

 absorption. An analogous phenomenon was displayed by Nova 

 Persei at one time in 1901, and Dr. Hartmann notes that the 

 component of the solar motion for both Delta Orionis and 

 Nova Persei almost exactly corresponds to the velocity indi- 

 cated by these stable calcium lines, implying that in both cases 

 the intervening calcium clouds are almost completely at rest rela- 

 tively to the stars from which the elements of the sun's way have 

 been computed. The distance from us of this cloud cannot be 

 determined, but its extent might possibly be ascertained by 

 observations of the K line in neighbouring stars. 



* * * 



Sunspot Variation in Latitude. 



An interesting discussion took [ilace at the last meeting of 

 the Astronomical Society on June 10 on the above subject. 

 Dr. \V. J. S. Lockyer recently communicated a paper to the 

 Koyal Society, stating that " Sporer's Law of Spot Zones was 

 only approximately true, Sporer's curves being the integrated 

 result of two, three, and sometimes four ' spot activity track ' 

 cur\'es, each of the latter falling nearly continuously in latitude." 

 The Rev. A. L. Cortie and Mr. Maunder both read papers on 

 the same subject, the former showing that the limiting lati- 

 tudes for large sunspots rose from miniuuun to maximun) 

 instead of falling in the manner described by Dr. Lockyer, and 

 that the " spot activity tracks " of which he spoke had no real 

 existence. Mr. Maunder showed that the Greenwich Sunspot 

 Results for the last thirty years fully confirmed Spiirer's Law, 

 and proved that there was but one general zone of tpot acti- 



vity in each hemisphere. When e\ery separ.itc spot group 

 was plotted dowMi according to its solar latitude, it was S(-en 

 at once that tliere were no such separate downward moving 

 " spot activity tracks " as Dr. Lockyer had described. 



•X- X' » 



The R-oya.1 Observator'y', Greenwich. 



The annuiil report of the .Vstronomer Royal to tht' Hoard of 

 \'isitors was read on S.iturday, June 4. The year's record 

 had been destitute of sensational incidents, the most note- 

 worthy being the great magnetic storm of October 31-Novem- 

 ber I. Hut the report records the completion, or near approach 

 to couiijlction, of a number of most important enterprises. 

 The publication of the first volume of the " Astrographic 

 Catalogue" was noticed in " Kno\vi,i:dgk " last mouth. The 

 photography for the Greenwich section of the " Chart and Cata- 

 logue " is complete, and the progress made in the observation 

 of the reference stars for the astrographic plates has been so 

 satisfactory that it is expected that the work will be com|)leted 

 next year. The revision of " Groombridge's Catalogue lor 

 iSio " and the determination of 4000 proper motions therefrom 

 are complete, and the results are about to be published. Con- 

 siderable |)rogr<'SS has been made with the measurement of the 

 photographs of b'ros, taki-u ni njoo and kjoi for the solar 

 parallax. The rainfall of the year 1903 was 35'54 inches, the 

 heaviest ever recorded .-it Greenwich during the calendar year, 

 but the amount of sunshim- registered was a little above the 

 average, and the number of oliservations made with the transit 

 circle suffered no diminution through the unprecedentcdly wet 

 character of the year. 



«- * -x- 



The Smithsonian Expedition to observe 

 the 1900 Solar Echpse. 



The Smithsonian Institution sent an expedition under Pro- 

 fessor S. P. Langley to observe the total eclipse of May, 1900, 

 at Wadesboro, S. Carolina, which was especially interesting in 

 view of the fact that its leader had observed the famous eclipse 

 of 1878, two complete solar cycles earlier, at Pike's Peak. 

 Professor Langley observed with the same 5-inch telescope 

 that he had used on the former occasion, and says that "the 

 inner corona was filled with detail, but far less sharp and 

 definite than he .saw it on Pike's Peak in 1S78. He could not 

 identify any connection between the coronal structure and the 

 presence of prominences, while his impression was that the 

 details contained more ngival curves than straight streamers. 

 Having in mind the wonderful structure seen with tiic instru- 

 ment in the clear mountain air 22 years before, the impression 

 was a disappointing one." This absence of connection be- 

 tween the prominences and the coronal structure was not 

 borne out either by visual or photographic observations at 

 other stations or by the photographs taken at his own camp, 

 for in his general sunnnary and conclusion Professor Langley 

 says that "large prominences were present, and these appear 

 to have been associated with regions of coronal disturbance." 

 He goes on to say that " the etjuatorial streamers were fol- 

 lowed on photographs to nearly four solar diameters, and were 

 then lost by reason of diminished intensity rather than as 

 appearing to end." This coronal extension, though not so 

 great as that photographed by Mrs. Maunder in ludi.i in 

 1S98, seems to be greater than any secured in any of the 

 other expeditions in 1900. The feature, however, in the 

 Smithsonian Expedition which excited the most interest 

 was the use of the bolometer, and though its results were to a 

 great extent negative in character, they were no less important. 

 Professor Langley says: "In the bolometric observations the 

 heating eft'ect of the inner coronal radiations was recognised 

 and found unexpectedly feeble. The results seem to indicate 

 a comparative weakness of the infra-red portion of the coronal 

 spectrum, alike inconsistent with (lie hypothesis that it radiates 

 chiefly by virtue of a high temperature, or acts chiefly as a 

 reflector of ordinary sunlight. This, taken in connection with 

 the appe;n'ance of the corona, seems to support the hypothesis 

 that the principal source of its radiations is of the nature of an 

 electrical discharge. The well-known polarisation of itsoiiter 

 portions, and the pn^sencc of faint dark lines in the outer 

 coronal spectrum, announced many years ago by J.iussen and 

 confirmed by the photographs of Perrine in the eclipse of 1901, 

 prove that a small portion of the coronal radiation is due to 

 reflected photospheric light. But the photographs of the 



