018 PHILOSOPHICAL TRANSACTIONS. [ANNO 1784. 



contain nebulae; and finding this to hold good more than once, I ventured to 

 give notice to my assistant at the clock, " to prepare, since I expected in a few 

 minutes to come at a stratum of the nebula?, finding myself already (as I then 

 figuratively expressed it) on nebulous ground." In this I succeeded immediately; 

 so that I now can venture to point out several not far distant places, where I 

 shall soon carry my telescope, in expectation of meeting with many nebulas. 

 But how far these circumstances of vacant places preceding and following the 

 nebulous strata, and their being as it were contained in a bed of stars, sparingly 

 scattered between them, may hold good in more distant portions of the heavens, 

 and which I have not yet been able to visit in any regular manner, I ought by 

 no means to hazard a conjecture. The subject is new, and we must attend to 

 observation?, and be guided by them, before we form general opinions. 



Before concluding, I may however venture to add a few particulars about the 

 direction of some of the capital strata or their branches. The well-known 

 nebula of Cancer, visible to the naked eye, is probably one belonging to a cer- 

 tain stratum, in which I suppose it to be so placed as to lie nearest to us. This 

 stratum I shall call that of Cancer. It runs from i Cancri towards the south 

 over the 67 nebula of the Connoissance des Temps, which is a very beautiful 

 and pretty much compressed cluster of stars, easily to be seen by any good teles- 

 cope, and in which I have observed above 200 stars at once in the field of view 

 of my great reflector, with a power of 157. This cluster appearing so plainly 

 with any good, common telescope, and being so near to the one which may be 

 seen by the naked eye, denotes it to be probably the next in distance to that 

 within the quartile formed by y, S, n, 9 ; from the 67th nebula the stratum of 

 Cancer proceeds towards the head of Hydra ; but I have not yet had time to 

 trace it farther than the equator. 



Another stratum, which perhaps approaches nearer to the solar system than 

 any of the rest, and whose situation is nearly at rectangles to the great sidereal 

 stratum in which the sun is placed, is that of Coma Berenices, as I shall call it. 

 I suppose the Coma itself to be one of the clusters in it, and that, on account 

 of its nearness, it appears to be so scattered. It has many capital nebulas very 

 near it ; and in all probability this stratum runs on a very considerable way. It 

 may perhaps even make the circuit of the heavens, though very likely not in 

 one of the great circles of the sphere : for unless it should chance to intersect 

 the great sidereal stratum of the milky way before-mentioned, in the very place 

 in which the sun is stationed, such an appearance could hardly be produced. 

 However, if the stratum of Coma Berenices should extend so far as (by taking 

 in the assistance of M. Messier's and M. Mechain's excellent observations of 

 scattered nebulas, and some detached former observations of my own) I appre- 

 hend it may, the direction of it towards the north lies probably, with some 



