ReflcBhns on the neiu Planet. f^ 



w'hich clifappear at another ? We are acquainted witli many 

 which have periodical changes of light of greater or longer 

 duration ; as, for example, thofe numerous chan-ieable Itars 

 called Sleihe miralnles. Whai has become of the celebrated 

 Tycho Brahe's Itar in Cafliopeia of the year 1572, which at 

 one time flione 7y< brii^ht as Sirius, and even exceeded VenuS 

 and Jupiter when in their perigeum ; fo that it could be feea 

 in the day with the naked eve; fince which time not the 

 fmallcil traces of it have been found ? We learn bv the old 

 chronicles, that in the lime of the emperor Otho I. about the 

 year 945, and alio in 1264 ", a new and motioniefs ftar ap- 

 peared between Cafliopeia and Cepheus. Some aftronomersj 

 therefore, conie6furcd that this might be the ftarof J573,which 

 appeared periodicallv in the courle of about 300 yearsf. Had 

 it anv alnnitv with the celebrated Itar difcovcred bv Kepler 

 in 1604 in the foot of Serpen tariii?, which feemed at one 

 time fo bright that it exceeded in fplendour ftars of the firft 

 magnitude, became inviiible next vear, and has never fince 

 appeared ? What are Hcrfchel's planetary nebulce ? Did not 

 Schroter % find that whole traces of luminous nebuhe diiap- 

 peared from the heavens ? What are our large fire-balls, 

 which move with a velocity a hundred times greater perhaps 

 than that of a cannon bullet, emit a bright light, burft, and 

 then disappear ? It is proved that thev are bodies belonging 

 to the univerfc, and not to our atniofphere. This was the 

 opinion of Montanari § in 1676, who, in his Fiannna I'o- 

 lante\\, calculates that oncof thcfc fire-balls, feen throughout 

 all Italy in the above year, was at tlic height of forty Ilalian 

 miles. Ail our readers muit remember the large fire-ball 

 feen in the year 1783 in every part of Europe, and pretty 

 well obferved. It was calculated by fome of the EngHlh aftro- 

 nomers that the height of this immenfe body of fire was 60 

 Englifh miles, and that its greateil diameter was 1 -th mile. 

 In feven minutes it would have pafled over a fpace equal to 

 the femidiameter of the earth 



Why may pot comets appear fomclimcs luminous and at 



* Lccivit. apud Tychon. lib. i. p. 441. F^icet. i'H. v. cap. i:. 



+ Sec Laplace's liv(>othc(ls on thisfubji-rt in his Exl>nft!. d'l Syjicmf tin 

 Mor.c/ey liv. V. p. 347. an. 7. the only real eil;tion in^uiii-to ackiiuvslcJged 

 by the author. 



* Bcytragc, p. j;2. 



§ Hailcy and Hevelius confidcrcd them alfo as cofinical bodies. 



{I La Fiamma volantc, gran Mereora vcduta Copra I'ltalia la fcr.i de 

 3 I Mario 1676, Sprcvilazioni fiiiche et alhonomichc efpn^flc dal Dott. 



Gcminiano Monranari in una Lcttcra idl, 111. Ecc. Sgr. Marcliefe 



Fedcrico Gonzaj^a, Bologna 1676. 05 pages <|U3rto: a very fcarcc work, 

 for which I am indebted to the kindncli of pioftflbr Klumcnbich, and 

 which Dr. Chhdiii, ^vho has coUcited on chib l"ubjc£t wiiK fo much care, 

 Ifras never al.lc to oLcalnf 



olhors 



