January i8, 1900J 



NA TURE 



271 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No nottce is taken of anonymous communications. ] 



Contemporary Meteor-Showers of the Leonid and 



Bielid Meteor-Periods. i 



Part 11. — Co- Bielid Showers. 

 Among nearly 120 meteor-tracks of the period November j 

 J0th-30th, partly seen here in recent years, and partly drawn 

 trom the Reports of the Luminous Meteor Committee of the 

 Hritish Association, of the years 1861-80, and among a list of ! 

 100 i9/V//V/- period meteor-paths observed in Italy, as will be 

 further illustrated and more especially described below, on 

 November I9th-30th, 1897, there were found to have occurred, 

 in this long-past years' collection, 30 Bielid meteors and 188 

 unconformable or ordinary nor.-Btelid meteor- tracks. Several 

 of the former meteors were recorded before the startling discovery i 

 in 1872, of the swarm of meteors connected with Biela's comet, 

 had made known the existence of a focus of cometary Biedd \ 

 meteors in this period near 7 Andromedae ; so that several I 

 evidently Bielid meteors of the list had nev-er before had their ! 

 true radiant-point, near 7, t Andromedae assigned to them. The | 

 'j;reat body of Bielid-\.ra.cVs having been subtracted, and the j 

 remaining 188 ordinary meteor-paths projected on a planisphere ' 



stream of r\ Taurids at about 56°, + 18°,^ this central shower ot 

 Taurids shows an almost cometary strength and stability of dis- 

 play, approaching in yearly constancy, although not at all in 

 proft^sion of its meteors, to the showers of August Perseids. 

 It produces, moreover, about the middle of November, a notable 

 number of large meteors, and even, as has been proved 

 in one case at least, also detonating fireballs. Its marked 

 superiority over ail the showers contemporary with it, only 

 excepting that of the Bielids, is easily seen by the slow gradation- 

 and comparative smallness of the meteor-frequencies noted in 

 the Table for the next most steady and productive showers. 

 But all these latter streams also considerably outshone the great 

 bulk of weaker streams marked by much fewer numbers of 

 satisfactorily assorted tracks ; and their six or seven especially 

 productive foci would no doubt, among many showers of very 

 variously interesting and eminent importance in the contem- 

 porary List, abundantly repay, in coming years, some further 

 study. To assist discussions by projections of any such new 

 observations, a few less productive radiant-points of Mr. 

 Denning's Leonid-Bielid Period List, may even, perhaps, be 

 here mentioned with advantage, although they each furnished 

 no more than four independent meteor-tracks, or 2 per cent, of 

 all the ordinary meteors' paths collected and compared together 

 in the mapped collection. 



Taking their numbers and positions as before from Mr. 

 Denning s list of fifty contemporary showers of the Leonid-Bielid 

 period, and adding in numbers and mean positions, D('99), of 

 a few shower-series from his extensive General Catalogue of 

 1899, the following were the recognised centres of divergence 



Table I\'. — Relative abtindances of meteors from different ordinary Meteor-showers in the Bielid Period, November 20th-yith, 

 among 188 ordinary and 30 Bielid shooting-stars mapped in some non-maximum Bielid nights of the years 1861-97 ; and relative 

 frequency of the Bielid meteors. 



Containing all the fifty radiant-points for the Leonid-Bielid period, 

 <>f Mr. Denning's Select List, the paths of all these meteors, with- 

 out any outstanding very refractory or certainly irreducible 

 exceptions, were found to be satisfactorily referable by trueness 

 of direction joined to suitable descriptions, to one or other of the 

 many radiant-points contained in Mr. Denning's List. 



Relative numerical strengths could thus be assigned to many 

 of the fifty contemporary showers, expressing the numbers of 

 tneteors traced truly and suitably back to all the best dis- 

 tinguished active sources, among about 30 more or less exactly 

 corroborated radiant-centres. For simplicity the numbers of 

 such meteors per hundred of all the 188 projected ordinary 

 meteor-tracks are noted, to show their relative numerical in- 

 tensities, against the seven most active of the thus detected 

 ordinary showers which are presented, in descending order of 

 meteor-density or shower-vigour, in the accompanying Table. 

 The percentage strength of the Bielid shower itself, which is intro- 

 duced for comparison with the less productive meteor-systems, 

 is reckoned on the same scale of proportion, to the total number 

 of non-Bielid meteors, with that of the slenderer displays, and 

 it only insignificantly outshone the brightest of those con- 

 temporary meteor-streams, from no observations having happened 

 to be made, in this collection, in any of the years when the 

 Bielid meteor-showers was at a maximum. 



The € Taurid shower, at 63°, +21°, stood nearly as high as 

 the Bielid stream itself, in marked abundance of its meteors. 

 Together with an apparently distinct, but perhaps associated 



NO. 1577, VOL. 61] 



of eleven weaker showers (or sometimes of small groups of 

 showers) each contributing about one in every fifty of the whole 

 projected number of ordinary meteor-paths. 



seen, almost entirely in 

 1897. 



I 9 + 34> * Andromedae 



D('99)39 44 + 57, "n Persei 



8 48 -h 43, &K Persei 



14 70 -(- 66, c , ox a Camelopardi \ scarcely seen in 1897. 



And nearer the equator, 



D('99)273 253 + 4, ' Piscium. 

 D('99)3 \ Q , Q i 7 ^^.?«« and 

 and 1 1 j ^ \^ Piscium. 



5 30-1- 16, a Arietis ) ,■ a • o 



6 43+ (>\aCeti 1 chiefly seen m 1897. 

 D('99)49 53 + 8, e or {o Tauri (three tracks only), 

 32 136 + 8, ^Hydrae; not seen in 1897. 



1 A good display of meteors of thi: 

 W. E. Besley, at Clapham Park, S.W., on November 8th. 



shower was seen this year by Mr. 

 , on November 8th. Seven bright 

 meteors (and another of ist magnitude on November loth), were noted in 

 the short space of ih. 48m., ending at i2h. 46m. on that night, with a very 

 well-defined radiant-point at 52°, -{-22°. Their apparent magnitudes in the 

 fixed-star scale were, 4, 2, i, 1,3, 2, \\, i,and they were long-pathed, slow, 

 trained meteors. Two of the brightest, at iih. 26m. and iih. 33m., on 

 November 8th, showed pale green colour in the heads. The meteors of the 

 showers near rj Tauri, at 56°, -|- 18°, it should be noticed, are chiefly observ- 

 able in the first half of November, and reach a well-marked maximum of 

 abundance on November 6th-ioth ; while the e Taurids, at (>^,-\-i\°, have 

 an equally distinct date of maximum on about November 20th, and are 

 usually seen in greatest numbers in the last half of November. 



