248 Mr, Herschel on the 



ocean, and therefore I fhall go no farther than the gages will 

 authorlfe ; but confideruig the little depth of the ftratum in 

 all thofe places which have been aftually gaged, to which muft 

 be added all the intermediate parts that have been viewed and 

 tonud to be much like the reft, there is but little room toexpedt 

 a connection between our nebula and any of the neighbouring 

 ones. I ouglit alio to add, that a telefcope with a much larger 

 aperture than my preient one, grafping together a greater quan- 

 tity of light, and thereby enabling us to fee farther into fpace, 

 will be the lureft means of compleating and eftablifliing the 

 arguments that have been ufcd : for if our nebula is not abfo- 

 lutely a detached one, I am firmly periuaded, that an inftru- 

 rnent may be made large enough to difcover the places where 

 the ftars continue onwards. A \txy bright milky nebulofity 

 niufl there undoubtedly come on, fuice the ftars in a field of view 

 will increafe in the ratio of n\ greater than that of the cube 

 of the vifual ray. Thus, if 588 frars in a given field of viev/ 

 are to be Icen by a ray of 497 times the diftance of Sirius ; 

 when this is lengthened to 1000, which is but little more 

 than double the former, the number of flars in the fame field 

 of view will be no iels than 4774 : for when the vifual ray r 



is given, the number S of flars will be::=^; where 72 — r+ i ; 



and a telefcope with a three-fold power of extending into fpace, 

 or with a ray of, 1500, which, I think, may eafily be con- 

 flrufted, will give us 16096 ftars. Now, thefe would not be 

 fo clofe but that a good power applied to fuch an inftrument 

 might eafily dlftinguifh them ; for they need not, if arranged 

 in regular Spares, approach nearer to each other than 6^^,27; 

 but what would produce the milky nebulofity which I have 

 ■mentioned is the numberlefs flars beyond them, which in one 



refpedl 



