44 JVf/. Herscheji's Catalogue 
fame. Let the phenomena of the adjufting ftar be well 
attended to ; as, whether it be per fed ly round and well de- 
fined, or affeded with little appendages that frequently keep 
playing about the image of the ftar, undergoing fmall altera- 
tions while it paffes through the field, at other times remain- 
ing fixed to it during the whole paffage* Such deceptions may 
be deteded by turning or unfcrewing the objed-glafs or fpecu- 
lum a little in its cell, when thole appendages- will be obferved; 
to resolve the fame way. Being thus acquainted with the 
imperfedions as well as perfedions of the inflrument, andi 
going immediately from the adjufling ftar, which for that 
feafon alfo fhould be as near as may be, to the double liar which 
is to be examined, we may hope to be fuccefsfuL The afire- 
nomica] Mr. Aubert, who did me the honour to follow this 
method with y Leonrs, which he did not find to be double 
when the telefcope was adjufled by y i’tfelf, foon perceived the 
fmall flar after he had adjufled it upon, Regulus* The inflru- 
ment, being one of Mr. Dollond’s bell feet achroma- 
tics, fhewed Mr.. Aubert the two flars of y Leonis in very 
clofe conjundion, or rather one partly hid behind the other. 
On comparing thefe appearances with my obfervations of that 
double flar, we muft not be furprifed to find that I place therm 
at a vifible diflance from each other : for the Newtonian re- 
Oedors, on the plan of my 7- feet one, as I have found, will 
give a much fmaller image of the flars than the 3! feet achro- 
matic refradors wherefore the two flars, which in refradors 
as it were run into each other, will in the refledor remain 
feparate. For this reafon alfo, thofe who only ufe fuch re~ 
fradors mufl not be difappointed if they cannot perceive the 
26th, 30, 31* 36, 41, 44? 46, 47? 60, 75, 82, 86, and 87th, 
ilars of my firfl clafs to be double. 
A 
