2,66 Mr. Herschel on the Conjlruciion of the Heavens. 



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

 if any i'uch they had, retarded in each others atmolphere, may 

 rufh at Lift together, and either in fuccefiion, or by one general 

 tremendous iliock, unite itito a new body. Perhaps the ex- 

 traordinary and iudden biaze of a new ftar in Cailiopea's chair, 

 in 1572, miglit pofiibly be of fuch a nature. Butleil I Ihould 

 be led too flir from the path of obfervation, to which I am 

 refolved to Umit mylelf, 1 fliall only point out a confiderable 

 ufe that may l>€ made of thele curious bodies. If a little atten- 

 tion to them ihould prove that, iiavlng no annual parallax, they 

 belong moft probably to the clafs of nebulae, they may then 

 be expe^^ed to keep their fituation better than any one of the 

 ftars belonging to our lyftem, on account of their being pro- 

 bably at a very great diflance. Now to have a fixed point 

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

 may be referred, is certainly of confiderable confequence ia 

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

 to anfwer that end (/6). 



Datchet fiear Windfor, W. HERSCHEI.. 



January i, 1785. 



{h) Having found two more of thefe curious objefts, I add the place of them 

 here, in hopes that thofe 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 diame- 

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

 very little elliptical, and all over of an xuiiform brightnt Is : with higher powers 

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

 5S 49' more north than that liar. 



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

 edges, but the hazinefs goes off 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 uniform brightnefs : I fuppofe the intenfity 

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

 third b (Fl. 6.) Crateris 28' 36'' in time, and is i" 25' more north tlian that flar. 



