266 Mr. Herschel on the ConJlruSiion of the Heavens, 



fit for their former purpofes, and having their projedile forces, 

 if any fuch they had, retarded in each others atmcfphere, may 

 rufh at lait together, and either in fuccefilon, or by one general 

 tremendous fhock, unite into a new body. Perhaps the ex- 

 traordinary and fuddcn blaze of a new ftar in Cafliopea's chair, 

 in 1572, might pofiibly be of fuch a nature. But left I fhould 

 he led too fc\r from the path of obfervation, to which I am 

 rcfolved to limit myfelf, 1 (liall only point o\it a confiderable 

 ufe that may be made of the^e curious bodies. If a little atten- 

 tion to them iliould prove that, iiaving no annual parallax, they 

 belong moll probably to the clais of nebulae, they may then 

 be expected to keep their fituation better than any one of the 

 (lars belonging to our lyflrem, on account of their being pro- 

 bably at a very great diftanee. Now to liave a fixed point 

 fomevvhere in the heavens, to which the motions of the reft 

 may be referred, is certainl}^ of confiderable conlequence in 

 Aftronomy ; and both thefe bodies are bright and fmall enough, 

 to anfwer that end (/6). 



Datchet near Windfor, W. HERSCHEL. 



January i, 1 785. 



{h) Having found two more of tliefe curioTis objefls, I add the place of them 

 here, in hopes that thoie who have fixed inllruments may be induced to take an 

 early opportunity of obferviug them carefully. 



Feb. I, 1785. A very bright, planetary nebula, about half a minute in diarae* 

 ter, but the edges are not very well defined. It is perfedly round, or perhaps a 

 very little elliptical, and all over of an uniform brightntis : with higher powers 

 it becomes proportionally magnified. It follows y Eridani 16' 16" in time, and 

 is 49' more north than that ftar. 



Feb. 7, 1785. A beautiful, very brilliant globe of light ; a little hazy on the 

 edges, but the hazinefs goes ofi" very fuddenly, fo as not to exceed the 20th part 

 of the diameter, which I fuppofe to be from 30 to 40''. It is round, or perhaps 

 a very little elliptical, and all over of an imiform brightnefs : I fuppofe the intenfity 

 of its light to be equal to that of a flar of the ninth magnitude. It precedes the 

 third b (Fjl. 6.) Crateris 28' 36" in time, and is 1° 25' more north than that flar. 



