250 



KNOWLEDGE. 



[November 1, 1897. 



shining in Gemini. On November 14th, at 3 a.ji., our 

 satellite will be forty-five degrees west of the Leonid 

 radiant, and on the following morning, at same time, 

 thirty-two degrees west. If, however, the full moon of 

 November 13th, 1864, could not obliterate the display, it is 

 certain that the gibbous moon of 1897 will not succeed in 

 doing so. 



As a spectacle for the popular eye it cannot be said that 

 the November meteors of the present year are likely to 

 prove strikingly attractive, though for the astronomical 

 observer they wUl be sufficiently numerous to incite 

 enthusiasm. The sky should be watched on the mornings 

 of both November 14th and 15th, for the exact time of 

 the best display cannot be indicated with certainty ; in 

 fact, we would prefer to depend upon future observations 

 rather than draw unsafe conclusions from a discussion of 

 the imperfect, and somewhat meagre, records of the past. 

 Quite possibly, since 1866, the stream has become distended 

 along the orbit, for there is little doubt that originally 

 compact meteoric groups gradually resolve themselves into 

 continuous rings similar to that of the Perseids, which are 

 prominently visible every year. The Leonids, too, are 

 annually manifested, but with strong periodical maxima, 

 showing that their dispersion is comparatively slight, and 

 that the system still exhibits a high degree of condensation 

 near the parent comet. 



Perhaps the following brief synopsis of facts relating to 

 this meteor stream may be useful : — 



Place of apparent radiaut point R.A. 149° 28', Dec. + 22'' 52'. 

 Approximate star (mag. 5'7) 



J- Lconis (Bode) „ 149" 10', „ + 22° 28' (1890). 



Eadiant point rises ... ... 10.15 p.m. in N.E. 



Altitude at midnight, Not. 14tli 14 degrees in E.N.E. 



„ „ 3 A.ir., „ I5tli 42 „ „ E.S.E. 



„ „ 6 A.M., „ 15th 61 „ „ S. by E. 

 Perihelion distance of stream.., 90,000,000 miles. 



Aphelion „ „ ... 1,850,000,000 „ 



Apparentrelocityof the meteors 44 miles per second. 



The shower of Leonids certainly endures during the 

 fortnight from November 7th to 20th, inclusive. In future 

 years it will be important to determine whether the radiant 

 becomes displaced about one degree per day to the east- 

 ward similarly to the radiant of the August Perseids. The 

 accumulated observations of past years are not extensive 

 and accurate enough to finally settle the point, for the 

 shower is exceedingly feeble near its opening and closing 

 stages, and requires watching during the whole night 

 before its visible activity can be brought distinctly into 

 evidence. 



It is clear, from the great interest which this meteoric 

 shower is attracting, that a very large number of observers 

 will witness it, record its leading features, and describe 

 the most brilliant meteors. It would greatly facilitate the 

 comparison and reduction of meteor paths if observers 

 generally registered them according to the right ascension 

 and declination of their points of appearance and dis- 

 appearance. To describe an object roughly with reference 

 to its compass bearings and altitudes, or according to its 

 place near prominent stars from or towards which it 

 passed, is not often sufficiently accurate for ascertaining 

 the real path in the atmosphere. A uniform method of 

 tabulating the results in right ascension and declination 

 is more desirable, as conducive to greater accuracy as well 

 as economy of time on the part of those who endeavour to 

 reduce such observations. 



In separating the Leonids from meteors belonging to 

 the minor showers of the period and deducing the horary 

 rate of the former, it must be remembered that there are 

 a number of radiants of streak-leaving meteors in the region 

 closely surrounding the sickle of Leo, and that these are 



very liable to be mistaken for Leonids. The following are 

 some radiant positions of these circum-Leonid showers : — 



R.A. Doc. B.A. Dec. E.A. Dec. 



125° -1-40° 141°+ 27° 154° -f 41° 



182° -(-21° 146° -f 8° 157° -I- 49" 



133°-t-81° 148°-12° 166°4-81° 



186° -h 8° 154°-fl2° 166° -f 8° 



In 1898 the November meteors will probably be well 

 seen, as the moon will be absent from the sky ; and apart 

 from that, the earth will pass through a region of the 

 stream comparatively near the parent comet and presum- 

 ably rich in meteors. And in 1898 there is also the 

 certain prospect of witnessing a return of the meteors of 

 Biela's comet, for a similar interval will then have elapsed 

 as between the splendid exhibitions of 1872 and 1885 ; 

 but on the date (November 23rd) of the expected return in 

 1898 the moon will be approaching the full, and partially 

 interfere with the success of the observations. 



THE BRITISH TRAP-DOOR SPIDER. 



By Fred. Enock, F.L.S., F.E.S. 



IF it comes as news to some of the readers of Knowledge 

 to hear that we have in Great Britain representatives 

 of trap-door spiders, it is not to be wondered at, 

 considering how very few students of natural history 

 bestow the slightest attention upon spiders, of which 

 we have at least five hundred and twenty different species. 

 This number might be considerably augmented were there 

 more workers in this most interesting branch. The time 

 was when those who ran after butterflies were looked upon 

 as mild lunatics, but happily that idea has passed away in 

 civilized towns— but in the country the line is drawn at 

 collecting spiders, as I can testify from my own experience, 

 for it is a fact that for over three years, whilst living 

 at Woking, I was looked upon by the natives as mad, and 

 called " The Madman," simply because I searched for, and 

 carried home, all kinds of spiders ! Even in London a 

 lady once asked me, in the most serious manner, if I 

 " realhi liked spiders " — to which I replied in the affirma- 

 tive, and received a withering look of pity which quite 

 failed to wither me — so hardened had I become in my love 

 and respect for spiders ! 



In that most dehghtful book by the late T. Moggeridge, 

 entitled " Harvesting Ants and Trap-door Spiders," we 

 find that numbers of species of trap-door spiders are to be 

 found in the neighbourhood of Mentone and the South of 

 France. This work is charmingly illustrated with a 

 number of plates showing the various types of " trap- 

 doors " with which the spiders protect the entrance to 

 their nests, which consist of almost vertical burrows about 

 half to one inch in diameter, and of various depths. These 

 holes are lined with silk, the edges bevelled off, and a thick 

 lid, composed of layers of silk, fitted so exactly that when 

 closed down on its marvellous hinge it is most difficult 

 to detect. The resemblance of the trap-door to the 

 surroundings is increased by the spider adding small 

 pieces of moss and lichen to the upper surface of the lid. 

 Unfortunately for science, J\Ir. Moggeridge died before he 

 had completed his interesting observations, but his work 

 wiU ever remain as an example to all earnest naturalists 

 who desire to become observers of the habits and economy 

 of minute animals, rather than to amass huge collections 

 of species. 



The one representative of trap-door spiders is well figured 

 in Blaekwall's " Spiders of Great Britain." It was first 

 discovered by a Mr. Brown, at Hastings, in the year 

 1856, and received the name of Atypus sulzeri. Many 



