Deckmber, 1901.] 



KNOWLEDGE. 



271 



Although the aye-aye is certainly far from being a 

 common animal yet it is probably less rai-e than is 

 often supposed. Its supposed givat rarity a])pears to 

 bo largely due to the dread in which it is held by the 

 natives, who can seldom be induced to capture a 

 specimen. It is believed to be endowed with the power 

 of causing the death of those who attempt its capture, 

 and it is consequently only some of the bolder natives 

 who will venture on this undertaking, and then only 

 after providing themselves with a chju'm to counteract 

 the effects of the creatures su])posed supernatural 

 power. Occasionally, according to ilr. Baron's account, 

 it is taken in traps set for lemurs ; but it is then, unless 

 the owner is possessed of the aforesaid charm, invai-iably 

 set at liberty, after being anointed with fat in order to 

 propitiate its goodwill and forgiveness. Only very 

 occasionally is a specimen offered for sale in the market 

 at TamatAve, when a good price — presumably from 

 Europeans — is alwa3's obtained. 



♦ 



THE REAL PATHS OF FIREBALLS AND 

 SHOOTING STARS. 



By W. F. De.n.m.nc, f.r.a.s. 



During the fifteen years from 1886 to 1901 tiic real 

 paths of 300 fireballs and shooting stars were computed 

 by the writer. The observations were principally made 

 at Bristol, at Slough by Prof. A. S. Heischel, and at 

 Bridg\vater by Mr. II. Corder. .Simultaneous watches 

 of the sky were arranged between these and several other 

 observers in various parts of the country for the special 

 purpose of obt^aining duplicate records of identical 

 meteors, and those who participated in the work having 

 been habitually engaged in this field, it is thought the 

 data which have accrued may be regarded as fairly 

 accurate. Most of the results of individual path-com- 

 putations have been already published in the Journals 

 of the Livei-pool Astronomical Societj* (1887-9) and 

 British Astronomical Association (1892-1901), the work 

 having been in part undertaken in connection with the 

 meteoric sections of the societies named. 



I have been arranging and classifying the results with 

 the object of deriving mean values for the various kinds 

 of meteors, as the materials appear to be sufficiently 

 ample to allow figures to be amved at which, if not 

 conclusive and final, will at least approximately repre- 

 sent the facts and possibly lead the way to a more 

 thorough investigation at a future time, when many 

 thousands instead of a few hundreds of trustworthy 

 observations of this kind have accumulated. The mean 

 heights, etc., are summarized in the following table : — 



• h*iii?ht ^^*" '^^° *^^'"' ^^^^ ^°- 



? height lentrth relo- ailiturle in 

 bpinn •'*' °' city per of <lia- 



-^ ending, path. sec. radiant, srram. 



Fireballs — Miles. Miles. Miles. Miles. Degs. 



Terv swift, witli s-trealis, 'i 



Perseids, Orionids, Leo- ^ S5-2 50 550 37-5 3'J 1 



nids, &c * 



Moderately slow, with-) 71-7 23-3 S-iO 18Z 35 2 



tolerablv high radiants ) 

 Slow-moring, low radiants 58 4 260 1160 14 C 16 3 

 Slow-movin.:, radiant* ■) .^.^ ^-.q joj^.^ jg.y ,-, 4 



close to liorizon > 



Shooting Stabs — 

 A'erv 8«i£t, with streaks, "J 



Pepcids, Orionids, Leo- f ^,j.- ..-.- ^3 3 410 3ti o 



nids, &c. , radiants pretty \ 



high ' 



Terv swift, with streaks, ■) -.3.3 gg.- j;,.;, 39.0 H G 



radiants low ) 



Bather slow, high radiants 671 474 272 19-3 47 7 

 Slowish, low radiants ... 602 51-3 35 5 17-4 15 8 



The following conclusions have been drawn from a 

 study of the results and from an examination of other 

 materials of similar character which have licen published 

 by various observers and conipulei-s from time to time. 

 Some of the statements have been made in previous papers 

 by the writer, but in a dclached and loss dolinito manner. 



The swift metcoi-s are decidedly higher in the atmo- 

 sphere than the slow meteors. The luminous flights of 

 fireballs ai'e much longer generally than those of ordinai-y 

 shooting stai-s. Both fireballs and shooting st;us from 

 low radiants have longer paths than those from radiants 

 at high altitudes. 



Nearly all the slow-moving fireballs are directed from 

 radiants in the vicinity of the horizon. The great 

 majority of fireballs travel slowly, and their radiants arc 

 placed in the western half of the sky and somewlicrc in 

 the region of the earth's anti-apex.* The most numerous 

 class of shooting stiirs would appeal- to be formed by the 

 swift meteors directed from radiants fairly elevated in 

 the eastern sky, but this will not be found invariably 

 true for all seasons, there being many strong showers 

 clustered at distances rather remote from the ape.x of 

 the earth's way and yielding an abundance of shooting 

 stai-s which exhibit a medium or slow rate of velocity. 

 Theoretically the swift meteors should greatly pre- 

 dominate were meteor streams generally distributed in 

 an equable manner, but this is far from being the case, 

 and the result is that moderately slow or slow metcoi-s 

 arc often more plentiful than any other class. It is 

 tiiic that our lists of real paths contain a gi-eat excess 

 of swift meteors, but it must be remembered that the 

 bulk of the observations has been effected during the 

 Lyrid, Perseid, Orionid, Leonid and Gcminid epochs, 

 when such meteors are exceedingly frequent, though most 

 of them have their origin in the special systems referred 

 to and do not prove a general prevalence of rajiidiy 

 moving objects. 



A singularly well-marked height at which slow-moving 

 fireballs disappear is 26-29 miles. Comparatively few 

 large or small meteors become extinct when between 31 

 and 42 miles above the eaith. Nearly all the well- 

 observed meteors have vanished either between elevations 

 of 20-30 or 45-GO miles. Fireballs are more frequent 

 within two hours or so after sunset than at any other 

 time of the night; in fact the number of these bodies 

 which make their apparitions in the evening twilight 

 is quite remarkable. They are also often noticed in the 

 morning not long before sunrise. This notable frequency 

 cannot be explained on the supposition that more people 

 being about at the hours stated than at other periods 

 near the middle of the night there would naturally be 

 more records of these objects. Regular meteoric ob- 

 servers do not witness many fireballs of the larger kind 

 because such botlies commonly make their appearance at 

 times either before or after the usual hours when meteor 

 watches are conducted, and indeed they often present 

 themselves when least expected and in conditions of sky 

 not well suited for their observation. 



The zodiacal constellations are very rich in prominent 

 fireball radiants. (Monthly Polices, 'Vol. LVII., p. .561.) 

 For insUnco, there are well-defined showers from Pisces 

 (Aug.-Sep.), Aries (Oct. -Nov.), Taurus (Nov.), Gemini 

 (Dec). Cancer (Jan.-Fcb.), Leo (Feb.-Mar.), Libra (April), 

 Scorpio (.lune-July), Sagittarius (June), Capricornus 

 (July-Aug.). and Aquarius (July-Aug.). The slow- 

 moving fireballs from radiants in the west would seem to 

 be usually isolated and to be unaccompanied by any 

 smaller meteors forming a definite shower-radiant. They 



• Month!;/ Notices. Vol. LIV., ]•. 538. 



