468 



NATURE 



[Jum; 17, I9C9 



OUR ASTRONOMICAL COLUMN. 

 ' Tub Knsuing Return of the Perseid Meteors. — The 

 sonson especially fuvouriible for the observation of meteors 

 may be said lo commence in July, and after the full moon 

 of July 3 of the present year the sUy will befjin to exhibit 

 a marked increase of meteoric activity. 'Ihe Perseids, 

 Aquarids, and many other showers give evidence of their 

 presence at about the middle of July, and alTord an abund- 

 ance of material to the vigilant student until about the 

 third week in August. 



It is true that the great, annually visible stream of 

 Perseids has been already fairly well watched, but it seems 

 likely that we shall have to accumulate data for several 

 future centuries before our knowledge of the system may 

 be rcgard<'d as pretty complete and satisfactory. We do 

 not know the period of revolution of the parent comet 

 and of that particular region of the meteoric group where 

 the particles are collected most abundantly, nor have we 

 learnt the precise nature of the variations affecting the 

 annual returns of the shower. The different conditions 

 occurring every year in regard to the weather, mooEilight, 

 &c., render it extremely dilVicult to form correct conclusions 

 as to the strength of the region encountered at successive 

 returns. 



During the forthcoming display it is to be hoped that 

 observers will record the apparent paths of all the brighter 

 meteors they may observe, for the computation of the real 

 paths of these objects is very important. 



The Solar Parallax, fro.m Observations of Eros. — 

 A preliminary account of the results obtained from the 

 observation of Eros, at Mount Hamilton, for the deter- 

 mination of the .solar parallax, is given by Prof. Pcrrine 

 in No. 150 of the Lick Observatory Bulletins. The 

 observations were made during the Litter part of 1900, 

 and the full discussion is reserved for publication by the 

 Carnegie Institution of Washington. 



The solutions of 126 equations, giving the correction to 

 the assumed value of the parallax, 8-8o", are given, and 

 the various methods of weighting the means discussed. 

 Finally, the value 88067" ±00025" 'S adopted as the 

 result. 



Comparing the results of a long series of daily meridian 

 observations with the ephemeris, an apparent periodicity 

 of the residuals is exhibited, the double amplitude of 

 the variation being 005s., and the period .about nine days; 

 this periodicity is not accounted for by the effect of any 

 known bodies, but there appears to be some relation to 

 the period of light variation of Eros during the opposition 

 of 1900-1. For a further discussion it will be necessary 

 to have brightness observations of Eros made at the 

 same times as the position observations, but it is thought 

 that, even should this periodic inequality be found to be 

 real, the final value will be but little affected. 



A Dot'ItLE-IMACE CCEI.OSTAT FOR DETERMINING THE 



Moon's Position. — In No. 2016 of Nature (June 18, 1008, 

 vol. Ixxviii., p. 152) Prof. Boys described an apparatus, 

 designed by Mr. Wade, of the Egyptian Survey Depart- 

 ment, for the field determination of longitude, the moon's 

 position being known. 



Mr. Wade has now adapted his apparatus so that it 

 may be used for the inverse problem, viz. the determina- 

 tion of Ihe moon's position when the longitude is known, 

 and a lecture in which he described the modified instru- 

 ment appears in No. 30, vol. iii., of the Cairo Scientific 

 Journal (March, p. 64)". 



The two mirrors of Ihe former instrument are com- 

 bined in a ru'lostat mirror, on which two distinct faces are 

 figured, the one to reflect Ihe moon's image, the other to 

 reflect the images of the reference stars. The instrument 

 having been adapted for photographic observations, the 

 difficulties of the moon's relative brilliance and differential 

 motion among the stars had to he obviated, and this has 

 been done by the interposition of an especiallv designed 

 prism before that half of the camera objective which forms 

 the lunar image. This prism reduces the brightness of Ihe 

 image, and, when rotated by a handle at a uniform rate, 

 corrects the moon's motion to stellar rate. Thus pholo- 

 trraphs are obtained showing a properly exposed lunar 

 image among a number of star images, and it only rc- 



NO. 2068, VOL. 80] 



mains to measure the positions of the moon's centre, or 

 a well-marked crater, and the stars. .\ number of diflicul- 

 ties and devices are explained in Mr. Wade's paper, but 

 cannot be given in a brief note. 



The Determination of the Solar Constant. — In No. 4, 

 vol. xxix., of the Astrophysicat Journal, Messrs. .\bbot 

 and Fowie, jun., discuss a number of improvements and 

 new results in solar-constant determinations. 



Among olh<r results is a new value for the effective 

 solar tempi'rature, which Mr. L. B. .Mdrich computed 

 from the previously published results, by lioldhammer's 

 process, and found to be 6200° absolute. In the previous 

 results, publishid by the Smithsonian observers, allow- 

 ance was made for the extreme regions of the spectrum 

 not observable by them, and recent research indicates that 

 Ihe corrections then applied were all too small. By 

 employing a quartz prism and magnaiium mirrors, it is 

 hoped 10 seitle this point definitely in future researches. 



.\noiher new point, arising from a comparison of the 

 iqoS and i<)o() results, is the suggestion that in 1908 the 

 intensity of the ultra-violet rays in sunlight, as compared 

 with that of the red rays, was less than in .Vugust, 190I) ; 

 Ihe proposed new outfit should enable the question of the 

 reality of this apparent variation to be settled definitely. 

 The " solar co:istants " for Ihe two epochs indicate no 

 such variation in the total emission. 



Pyrhcliometric experiments during 1908 gave a correc- 

 tion to the unit of energy previously employed which 

 entails a lowering of the 1902-6 " solar constant " values 

 by 76 per cent., whilst the correction for ihe unobserved 

 infra-red ;ind ullra-violet radiations would raise them about 

 10 per cenl. 



THE WELSH GORSEDD. 

 'pHE ritual of the present-day Welsh Gorsedd, while it 

 ^ attracts the curious crowd, arouses the indignation 

 of many sobir-mindcd nationalists, who deplore the 

 tendency to " popery " so manifest in their fellows. But 

 while these good people remain outside the mystic circle 

 to rail and storm, every effort to persuade the bards tc 

 give up thi' (~iorsedd and its ceremonies has been unavail- 

 ing. The Gorsedd of the bards has grown year by year 

 in its influejice upon the life of the nation until it has 

 become the centre of authority for holding the only truly 

 national assembly of the Welsh people — the National 

 Eisteddfod. 



The bards, however, have done very little to satisfy the 

 curious or 10 appease the indignant by a rational explana- 

 tion of their doings, with the result that in certain quarters 

 judgment has gone against them by default. 



Perhaps the most serious effort to show them the evil 

 of their ways was that of Prof. J. Morris Jones, of Bangor, 

 during 1.S9I). In a series of articles published in Cyiiiri< 

 of that year he deplores the spirit of formalism that is 

 on the incre.ise in the " world and Church," and avows 

 that it is " full time for the country lo understand more 

 plainly the true history of the Gorsedd " and the " fiction 

 and deceit upon which its claims are based." The articles 

 are five in number, and it must be admitted that they are 

 a masterly contribution to the history of liorseddic litera- 

 ture of modern times ; since they appeared they have been 

 considered as containing the last word on the antiquity 

 of the Gorsedd, and as the author holds a position among 

 the highest authorities on the poetry and language of 

 Wales, it is in the nature of things that the results of 

 his inveslig;ition of this subject should carry great weight. 

 That this is actually so we will quote a paragraph from 

 a very important book on Welsh history in general, " The 

 Welsh People," by Sir John Rhys and D. Brynmor Jones. 

 In chapter xii. of that book, dealing with the " language 

 and lileralurc " of Wales, an allusion is made to the 

 Eisteddfod, and a quoiation is given from the " Laws of 

 Ilowel nda " concerning the ceremony of chairing the 

 bard. In a footnote relating to this quotation Ihe follow- 

 ing comment is made : — " We abstain from saying anv- 

 thing about Ihe ' Gorsedd ' as its antiquity is contested. 

 See ryiiirii for iSoii. where the reader will find several 

 articles on the subjeri bv Prof. J. Morris Jones, whom 

 we have to thank for calling our attention to the passage 



