October 7, 1897J 



NATURE 



543 



so bright among the latter class of meteors j from which it would 

 appear that the maximum of this year's weak display was pro- 

 bably impending still and not yet arrived at until after (lay- 

 break on August II, when at ih. 45m. a.m. on that morning, 

 M. Libert ended his long watch of the shower on the night of 

 August 10. With one stray flight from v, f Persei, six of the 

 ten Perseid meteors seen by Mr. Hardcastle diverged from 

 Tj, i- Persei, and three from B, C. Camelopardi. A bright 

 streak-leaving Perseui from the latter radiant-point was also 

 noted, with seven non Perseid meteors in one hour, at Lyming- 

 ton, as late as the night of August 19. 



A long-continued watch was kept for 5^ hours at Exeter, on 

 August 9, by Mr. W. E. Besley, and the paths of 108 meteors 

 were recorded {£»:^/ts/i Mechanic, vol. Ixvi. p. 16, August 20, 

 1S97), among whose projections on a map, he states, a very dis- 

 tinct radiant-point of 71 Perseids was shown at 43^", -f 57°; 

 extremely near the place, at 43° "6, -f 57°- 1 assigned by Dr. 

 Kleiber for the cometary mainstream of the shower. No 

 evidences of a companion-stream at B, C Camelopardi seem to 

 have been noticed among the Perseid-paths by Mr. Besley ; 

 though it seems not impossible, in a case of such near contiguity 

 of two co-operating meteor-streams, if only a few, or scattered 

 tracks from the less productive stream, perhaps, were noted, 

 that some real traces of the weaker and difiuser close-adjoining 

 -hower's existence, might easily be overpowered and hidden by 

 he close-crowded group of path-lines round the principal 

 -iiower's centre. 



In a previous, almost equally extensive watch, however, kept 

 on the nights of July 30, and August 2-4, at Westminster in 

 London, of the results of which, in the English Mechanic (vol. 

 Ixv. p. 601, August 13, 1897), Mr. Besley also gave a most 





Oj/^tr^. I 



M 



n 





~fDl. Hit, /XA. f3.k /AA /si 



<6j3 C3 > ■ ;-HA)3f/>.- 



f3>-W>T- 



±SJL 



-tfHJq-i I — ^2p2)- 





•-{/]— -4- 



Vi ^fii^H t itflO) UTf a/ntLlpifisi/r-CMxlKa^ .J 





A.5H. 



WE.B. 



£A^ 



ASJL 



JSAR 



excellent condensed description, 47 meteors were noted at times 

 almost simultaneous, on August 2 and 3 with my watches here ; 

 and together with three non- Perseid radiant points in Triangulum 

 and Andromeda, and near C Persei, a distinct radiant-point 

 which Mr. Besley regarded as that of the " true Perseids," was 

 nl)tained from five meteor-paths, lour on August 3, and one on 

 \ugust 4, at 321°, + 57^" ; only 2° from, the place at 35°, + 56°, 

 \here on the night of August 2 the radiant-point III. first 

 .allowed itself distinctly in my watches, accompanied by a closely 

 adjoining and equally distinct and productive shower-centre (the 

 shower II.) at 30°, + 54°. Although my watch and Mr. 

 Besley's were partly contemporaneous on the night of August 2, 

 when six and ten meteors respectively were noted here from the 

 close pair of radiant-points III. and II., yet the five "true 

 Perseids" mapped by Mr. Besley were not seen among the 

 16 meteors whose paths he recorded on that night, but among 

 the 27 noted on the following night and one on the night of 

 August 4. These dates of our recorded maxima seem, however, 

 to have been only apparently in disagreement, because, as the 

 above diagram (Fig. 2) of the hours of watching shows, the rate 

 of appearance of the " x-Perseids"^ was at the most only three 



1 The star x, and the conspicuous star-cluster in Perseus in which it 

 appears to the naked eye to be involved, are situated at about 32^°, -|- j6}°, 

 within i°of the place assigned by Mr. Besley to the Perseid radiant- 

 point on August 3-4, and only 2° or 3° from the places which were here 

 obtained for Radiant III., at 35°, -f 56°, on August 2, and 36°, -(- 55* for 

 July 30-August 8. The star's name may thus be used conveniently, for 

 shortness, as is done above and at a few former places in this r/sum/, to 

 distinguish this radiant-point III. from the earlier Radiant II. near 

 4 Persei from July 30 to August 4, which seemed to precede it there quite 

 distinctly and in good agreement with the theory, both in R.A. position 

 and in time. 



per hour, and in the times lost in noting observations, either 

 shower might thus easily pass by unnoticed in a watch, for each 

 of us in turn on those two nights, only barely extending to two 

 hours. 



In short watches on August 3, 4, and 5, at Lymington, three 

 meteors proceeding from the " x-Persei " position were mapped 

 by Mr. J. A. Hardcastle, and a second Perseid on the latter 

 date from between v and ^ Persei. The first two path-lines' 

 directions backwards, passing on either side of x to a point of 

 intersection at 33°, -f 54° (about 3^ south of x). and that of the 

 third within 1° east of or preceding x Persei, through 32', -f 57°. 

 One " </)-Perseid" and four sporadic meteors were also mapjied 

 at Lymington in a short watch on August 6, and nine sporadic 

 meteors, but no shooting-star from Perseus, on August 7 ! 



There seems to be clear evidence in all these observations 

 that pretty consjiicuous appearances are observable in July and 

 August, of well-marked brief baltnes of Perseid shooting-stars, 

 which follow each other in a regular order up to the chief annual 

 display, from about three weeks before it ; and additional ob- 

 servations of these feeble meteor-currents will be very useful to 

 determine the exact durations, radiant- point positions and re- 

 lative intensities as well as variations of intensities in future 

 years, of these weak supplementary streams apparently derived 

 by thinning out of the main current's ring-like, lengthened 

 cluster, on the ring's preceding side. 



In the Perseid meteor-swarm's original progressive lengthen- 

 ing by dissimilar times of revolution and orbit-.sizes among its 

 individual meteors, until the slower- and faster-moving stream - 

 ends overlapped each other along the orbit in several repeated 

 circuits, the slightly different-sized orbits must be a little dif- 

 ferently affected and impressed with node-line motions by 

 planetary disturbing actions, and they must thus have gradually 

 become very slightly separated from each other. But in the 

 case of any local knot or condensation which the original meteor- 

 cloud may have contained, from the very approximately equal 

 revolution-times and orbit-sizes with which the meteorites in 

 such a small cometary knot or parcel would all set out together 

 from the scene of initial disturbance which first deflected the 

 Tuttle's comet meteor-cluster of Perseids into its present long- 

 elliptic orbit, the densities and contracted limits of such small 

 groups at intervals along the winding convolutions of the 

 lengthy coil, would rftiturally still be retained, though less com- 

 pactly, compared to poorer intervals between them ; and weaker 

 annual showers flanking the main one at some constant distances 

 in time and longitude before or after it may thus be expected to 

 be visible, like the present short series of them, or like the 

 larger train of attendant Perseid -showers which Mr. Denning 

 has recorded, all verifying Dr. Kleiber's view of their origin so 

 exactly by their radiant- point positions. 



But the mean rate of motion in longitude of my few observed 

 shower-centres, although also in very distinctly good and not- 

 able agreement with the theory, appears to have been a little 

 over-rapid, or ahout 22" in eighteen days, instead of a little less 

 than 1° per diem ; and long-maintained activities of the grander 

 central and of the laterally cast-off poorer meteor-streams 

 seemed also in my watches to be as clearly evident and nearly 

 as prominent a property of their radiations as the advance in 

 longitude, both by often noted derivations of single and sparse 

 meteors from them on very different dates from those of the 

 showers' maximum abundances, and more especially by maxima 

 of some of the showers having been noted simultaneously (as 

 those of the showers II. and III. together on August 2, and of 

 showers III., IV., and V. together on August 8 and 9), in.^tead 

 of, as the theory postulates, and as the showers I. and II. ex- 

 emplified much more distinctly and it may quite possibly be 

 shown hereafter by further better observations, more truly and 

 correctly, with an interval of some few days between them in 

 succession. 



The mode of the figure's construction which shows the 

 radiant-point directions of the 1 14 Perseid paths recorded, re- 

 quires a little explanation. As my view of the sky was chiefly 

 overhead (embracing the north pole of the ecliptic the more 

 readily to detect any changes in longitude of the radiant- point's 

 position), the observed meteor-paths from Perseus nearly all 

 shot upwards, and would confuse each other by cross-inter- 

 sections if it were attempted to represent all the four or five 

 radiant-points together by their means, on a single map. But 

 as only depictions of the path-directions traced back to the 

 several radiant-points, and not of the paths themselves were 

 needed for the figure, these direction-lines only are represented 



NO. 1458, VOL. 56] 



