1S06.] Mr.Farey, on Shootivg-Slars, I'etecrs^ S(c. lis 



trious employer and patron in this and 

 Otlier uleuii and curiuus purfuits. 



Tlie want of leil'iire has lincc prevent- 

 ed, the exact correction of the time (from 

 that (lievvn by my clock) when each of 

 tlicfe fcries of obfervations vvtre made; 

 and the making of a co'.npai'if jn of tlit 

 intervals between fuch hars as (hot or 

 moved in the J'ame, or nearly hmiiar, di- 

 rections, ia order to fcarch for the re- 

 turn of particular futclJifula; if fortu- 

 nately any I'uch iliould have been feveral 

 times obferved. 



During thefe obfervations, repeated 

 opportunities occurred for myfelf and 

 my alTiftauts to notice all gradations of 

 the phenomenon, from the very minute 

 fliootinf::-ilars wliich inltantaneoully dart 

 for fliort diftances, often not more than 

 two or three degrees, and can be only 

 feen under very favourable circumftances, 

 as to the clearnefs and degree of illumi- 

 nation of our hemifphere at the time, to 

 thofe larger kind of meteors whicli attract 

 e\ery one's attention by their brinlitnefs 

 and the length of their apparent courfe ;* 

 and nothing has occurred in all thefe en- 

 quiries to ihake the opinions above men- 

 tioned, but, on the contrary, I think 

 tliem confirmed in every particular. 



Let us now conlider fonic of the circum- 

 ftances oCafatc/litula, or meteor, revolving 

 round, or kept from falhng direct to the 

 earth, by its projectile or centrifugal force 

 in its orbit ; and enrjuire, by tlie help of 

 Kepler's famous rule, as to the diftances 

 and periodic tiir.es of planets and fatcl- 

 litcs, viz. " the J'ijuarca of the periodic 

 times are as the cubes of the mean dif- 

 tances," what mult be the time fpent in 



* Few perfons, until they have carefully 

 atten'iej to the fubje.ft, can be aware how 

 Very r.^-quently iliooiing-ftars can be feen in 

 all their degrees, evsu their more ftrikine ap- 

 pearances ?.s Lrilliant fmall meteors by thofe 

 |iurpc/fely looliing out for fuch phenomena ; 

 while the obfervarions cal'uall% maue, if more 

 tarcfuily coUefted, woulJ be ound vcr)' nii- 

 ner.iiis. Your meteorological reporter, at 

 page 103, records a meteor fcea by him 

 nearly over London, on the Kjth, at 9 h. i2 

 m. p. M, ; and by a letter of the 2nd inftant, 

 vhich I received from Mr W Bafkcrville, 

 c' Hope's Htai Alley, he favif anotiier meteor 

 pafs over Lomlon on t'le 17th, at 9 h. P. M. 

 aifterent from the one which I have CeC ribed j 

 unlefs, inoecd, Mr. B. could be miitaken as 

 mucb as an hour in the time of the appear 

 ance he mentions, which in feveral o its 

 Other [uiticulars, ag -es with Meflrs. Foster 

 and Hubert's oblervationiat U h. on the fams 

 evening. 



AIOMKLy Mag. No. 14T. 



the complete revolution of a fulellitufa to 

 fupport iti'eif by its voioiity ni an orbit, 

 at 1, 2, S, &c. to if) niilcs refjeruveiy 

 abo\e tie <a;th*s fiafa^e; thus, as the 

 cube of 240,000 milts 'the intau d ftamce 

 of tlie IMoon from tlie Earili's cemre; ; is 

 to the fquai e of Q,'S(JO 588 icconds (,the 

 time of the Moon's revolution^ ;: fo is 

 the cube of G980 (one miie more thaa 

 the mean radius of the l-'artlij : to 50-11 

 feconds, or 1 h. 24 m. 1 f., the t:me of 

 a revolution at 1 mile hi'_h. In like 

 manner. .5043", 5045", 5U4 7", 5049*', 

 5051", 3053", 5054", 5050", and 

 5,058", aie the periodic times at 2, 0,4, 

 5, C, 7, 8, 9 and 10 miles refpcctively 

 above iJie earth's iurfacc* If we en- 

 quire the meay velocity per fecond, of a 

 Jatelliiuhi revolving at 1 mile above the 

 earth's furface, we have S,080X2X 

 3-141503-r-o041zr4-9(jl miles the velo- 

 city nearlv per fecond ; and, in like 

 manner, 4-960, 4-9ti0, 4-95J, 4-958, 

 4-958, 4-957, 4-95(3, 4-955, and 4-955, 

 are tlie velocities in miles refpectivelj', 

 neccflary tor re\oluiion at 2, S, 4, 5, 6, 

 7, 8, 9, and 10 miles above the earth's 

 furface. 



Accordiag to the obfervations upon the 

 meteor of the 17th of July, triven at p. 

 104, ;in apparent arc or courfe of 77* 

 was delcribed in 7" of time, w hich gi\es 

 11° of apparent motion in 1* ; and, fup- 

 poiing it was moving at the rate of 4.9(J1 

 miles per fecond, the vclotiiyneceflary to 

 maintain itfelf from fulling at 1 Ji'.ife 

 high, we have 4 -9G 1-4- tangent of ll°rr' 

 25-522 mi:es, the direct or hypotheimlal 

 diliancc nearly of the meteor in this cafe ; 

 in like manner we il.all find 25-518, 

 25-515, 25-511, 25-508, 25-.o04, 25:500, 

 25-497,25-490, and 25-490 miles reijiec- 

 tivelyas ti;e diretr diltance^,fapj.oling the 

 meteor le^oivinti either at 2, 0, 4, 5, G, 

 7, 8, 9 oi 10 miles high rcfpectivciy. 



>; ow, iince this meteor \a as feen ia Lam- 

 beth at 15" ofeknationjC^"^ bcforeit crofl- 

 ed the meriduui or foutli poiiit, and when 

 44° pait the fame its elevation was 11°, 

 It is r afonahle to conclude that 1?-^° 

 was nesr y its altitude when on the vno^ 

 ridian; and if on paper we project an 

 aiigle of 1S|°, a the angle at the baife, 

 or at the obferver's eye, of the 'rii:ht- 

 aii^led trian<;ie, whofe hvpothenufe is 

 the direct diltance of the meteor when S. 



■ * At 'lO miles high, the prr.ba!.<le limits 

 of the atmofpiiere, the periodic time v.ill be 

 found .) I lb", and the velocity 4-yiS miles 

 {'fv k-coftd. 



T atul 



