124 



NA TURE 



[January ^, 1900 



The important calculations of the perturbations of the Leonid 

 meteor-stream by the major planets since the year 1890, recently 

 published by Dr. A. Berberich, of Berlin,^ in which the effect 

 of those perturbations to alter the form of the stream's orbit and 

 hence the distances from the sun, at ihei;' nodes, of those parts 

 of the stream which the earth would encounter, respectively in 

 November of the years 1898 and 1899, led that distintruished 

 German .astronomer to the conclusion that inward deflections 

 towards the sun of 0-0163 ^"d o 0048 earth's orbit radius, or of 

 about one and a half, and half a million miles respectively, 

 would be produced in the two meteor clusters at their nodes, by 

 the special perturbations exerted upon them respectively by the 

 major planets ; and as the orbit of Tempel's comet of 1866, 

 which they may be supposed to have been nearly following, 

 passed already at its node, in January of that year, at o'oo65 

 earth's orbit-radius, or 604,000 miles inside the earth's orbit, 

 the offing distances of these two clusters' centres on the inside 

 of the earth's track when the earth passed near them in 

 November, 1898 and 1899, would be respectively about two 

 million and one million miles, if they pursued the same orbit as 

 the comet had in 1866, before undergoing the exceptionally 

 strong perturbations ; while in their previous revolution they 

 would have been but little more than half a million miles inside 

 the orbit of the earth ; and if the meteor clusters passed through 

 in 1866 and 1867 were also moving along the comet's orbit 

 then, and sufficed to produce imposing meteor-showers when the 

 earth approached to within about half a million miles from their 

 stream centres, it need certainly excite no wonder if no meteor- 

 showers of extraordinary brightness should have happened to 

 occur on the November dates of 1898 and 1899, when the earth 

 approached no nearer than to two million and one million milts 

 from the meteor-current's centre 



But Dr. Berberich's investigation really showed what marked 

 differences of effect are produced by the planetary perturbations 

 on different portions of the long meteor-stream, so that instead 

 of any parts of it now following exactly the same orbit as the 

 comet, it must all have become waved and sinuous along a mean 

 orbit path ; and no prediction of the showers probable intensity 

 at a new return can be at all based certainly on an apparent 

 centrality and on great brightness of its just previous periodical 

 appearance. The succession of fine showers of 1799, 1832-3, 

 and 1866-7 appears to have been interrupted for the present by 

 some such deformations impressed by past perturbations, during 

 nearly twenty centuries, on the meteor-current. But these may 

 be replaced next year, with equal probability, by new and con- 

 trary ones in the portion of the stream which the earth, it may 

 be hoped, will pass through more centrally than seems to have 

 occurred this year, in November, 1900. It may also still be 

 somewhat premature to regard the strength of the November 

 shower as having fallen this year beyond all traces of resem- 

 blance below its anticipated brightness, until detailed reports 

 _ may still for a long time be expected from many anxious meteor- 

 ' watching stations in the Antipodes, like the great observatories 

 -of Australia and the younger, but yet very well equipped 

 meteorological and astronomical observatory at Hong Kong. 



The following were the times of observation, (Table II.), and 

 the radiant-point results, (Table III.), of my recent morning 

 views, in clear sky, of 69 non-Leo7tid and five Leonid shooting- 

 stars seen in the I2hrs. watch on November 6th-i6th. The 74 

 meteors were for the most part small, only about twenty having 

 surpassed third magnitude stars, and none having exceeded the 

 brightest fixed stars in brightness. Only six or seven uncon- 

 formable meteors, besides one Leonid, left momentary light- 

 streaks ; two from the radiant at k, and two from radiants near 

 •Tr or p Leonis, and two more from the radiant near the equator 

 at p, 29 AJonocerotis. A greenish-streaked, ist magnitude 

 meteor from this latter point, on November 8th, had, in fact, 

 so perfectly the appearance of a true long-pathed, swift Leonid, 

 as quite to deceive me, at first, into a supposition that it must 

 surely be a fine and very early harbinger of the coming meteor- 

 shower, until its path was mapped and traced liack to its real 

 Monocerotid centre. 



With the exception of a (c Le,>nid on the morning of Novem- 

 ber 14th, the thirty-eight meteors grouped under the five co- 

 Leonid radiant centres in Table III. were all seen among sixty- 

 four ordinary shooting-stars on November 6th-ioth ; the four 

 remaining ordinary meteors added to the list in broken watches 

 in the following very clouded star-shower nights, having all 



1 Astronomische Nachrichten,'^o.-^^'2(>, October; and The Obseri'ato>y, 

 vol. xxi. p. 4t6, December, 1898. 



NO. 1575. VOL. 61] 



belonged to very feeble showers from other ordinary centres. But 

 the five L^eonids seen then in a few restricted glimpses of the 

 sky, gave a pretty exactly defined radiant-point, which, though 

 obtained from several different nights of observation, might yet, 

 it was thought, be esteemed accurate enough, and of sufficient 

 general interest to be included in the Table. 



The paths were all projected on a chart of stars laid down for 

 the epoch a.d. 1900, on the extraordinarily accurate gnomonic 

 polar net drawn to single degrees of right-ascension and declin- 

 ation about a centre of projection in declination 45°, by Prof. 

 Lorenzoni, and published at the astonishingly low price of 0"4//;-« 

 (about i\d.) per large " double-crown "-sized sheet of exquisitely 

 printed zincographic engraving, at the Meteorological Observ- 

 atory of Fontaniva, Venice, for the use of Italian and other shoot - 

 ing-siar observers. The radiant-point positions were thus very ac- 

 curately extracted, and the unusual precision of thegnomonically 

 ruled map seems to have been very strikingly illustrated by the 

 smallness of the areas from which the tracks referred back to 

 each of the radiant -points diverged. The radii of these circular 

 areas drawn round each radiant, as a centre, of just sufficient 

 width to include the most distant of the path lines regarded as 

 belonging to that radiant, are shown in the third column of the 

 Table. But they sometimes overreached the proper smallness of 

 a focal region, when only one or two very outlying path lines 

 occurred, as happened in the plotted set of | Taitrid paths, 

 among an otherwise well centred group of path-directions. 

 The concluded centre-places were compared with two radiant- 

 lists published by Mr. Denning ; one of fifty ordinary meteor- 

 showers visible at about the same time with the Leonids (or, 

 about a week later, also with the Bielid meteors),' and the other 

 his extensive "General Catalogue" above referred to. The 

 first and fourth columns of the Table give the Numbers in those 

 two Lists, of separately accounted " Co-Leonid" streams, and of 

 more or less long-enduring ordinary meteor-systems, or ' ' shower- 

 series," with which the present set of showers appeared to be 

 identical; and the average positions of the latter "shower- 

 series," as given with their running numbers in the catalogue, in 

 the " Index-List" of Mr. Denning's " General Catalogue," are 

 added in the fifth column of the Table to the preceding column's 

 Numbers in that General Catalogue, or its Index-List. The 

 agreements found, very closely confirmed the two lists' positions, 

 excepting in the ca.se of the main stream of Taurids, which, as 

 I hope to recur to hereafter in a communication of some notes 

 on large co-Leonid and co-Bielid meteors to supplement this 

 letter, appears on this occasion to have proceeded from a rather 

 outlying centre, rather nearer to o than to e Tauri. 



A shower centre at |, o Tanri, very prominent in October 

 and November, apparently reaches its maximum on November 

 2nd, when Mr. Denning noted its place very exactly, in 1886, by 

 a considerable shower of seventeen meteors, at 55°, +9°. One 

 member of this stream, it has been already mentioned, with a 

 radiant-point at 55°, -t- 4°, was doubly observed at Bristol and 

 Slough this year, on November loth ; and another as early as 

 September 17th, in 1898, by Mr. A. King, at Leicester, and here, 

 brighter than stars of the first magnitude, with a radiant-point at 

 57°, 4-7°. The shower was well defined this year by many 

 tracks, very near its mean position in Mr. Denning's "General 

 Radiant Catalogue," although no place seems to have been ac- 

 corded to it in the select List of Fifty Showers visible at the 

 same time with the Leonids. The/, q, or " 30 Monocerotids'" 

 (No. 3), which form a rather weaker shower-series of similar 

 duration to the f, or " e Taurids," and which furnished a few- 

 bright streak- leaving meteors this year from close to their mean 

 centre in the " General Radiant Catalogue," are also missing 

 from, and are no doubt properly passed over in the special 

 co-Leonid List, as they not only formed a less plentiful .shower 

 than the I Taurids, in these watches, but they were also not all 

 quite .so certainly assignable as were the great majority of the 

 I, Taiirid tracks, to their adopted centre. 



Among many recorded radiant-points near Leo's Sickle, only 

 that near k Leonis was found to be distinctly active, presenting 

 itself very sharply before any true-directed " 7 Leonid" meteor- 

 paths were charted ; and though only a slender shower of 

 slightly streaked and rather sparingly bright meteors, it must 

 doubtless produce on ordinary Leonid shower nights some of 

 the swift shooting-stars resembling L.eonids which in yearly 

 watches for the great shower's return, are sometimes seen 

 diverging Irom a little north of Leo. On the morning of 

 November 14th, 1877, a marked abundance of apparently just 

 1 Astroiiomische Nachrichten, No. 3513 ; August, 1898. 



