44 Mr. Herscheis^s Catalogue 



fame. Let the phaenomena of the adjufting fiar be w^ll 

 attended to ; as, whether it be perfe<flly 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 pafles through the field, at other times remain- 

 iiig fixed to it during the whole paliage. Such deceptions may 

 "fee detected by turning or unfcrewing the obje6t-gl.ils or fpecu- 

 lum a little in its cell, when tliofe appendages will be oblerved 

 to revolve the fame way. Being thus acquainted with the 

 imperfections as well as perfections of the inflrument, and 

 going immediately from the adjufting ftar, which for that 

 reafon alfb fhould be as near as may be,, to the double flar which- 

 is to be examined, we may hope to be fuccefsful. The afire* 

 nomical Mr. Aubert, who did me the honour to. follow this, 

 method with y Leonis, which he did not find to be double 

 wheathe tekfcope was adjufled by y itfelf, foon perceived the 

 fmall ftar after he had adjufted it upon Regulus. The inftru- 

 ment, being one of Mr. Doi.lond's befl 3! feet achroma- 

 tics, fhewed Mr. Aubert the two ftars 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 mufl not be furprifed to find that I place them, 

 at a vilible diftance' from each other: for the Newtonian re- 

 fle<5lors, on the plan of my 7-feet one, as I have found, will 

 give a much fmaller image of the liars than the 3I feet achro- 

 matic refractors; wherefore the two ftars, which in refradtors- 

 as it were run into each other, will in the reflector remaia. 

 feparate. For this reafon alfo, thofe who only ufe fuch re- 

 fractors muft not be difappointed if they cannot perceive the 

 26th, 30, 31, 36, 41, 44, 46, 47, 60, -j^^ 82, 86, and 87th. 

 flars of my firfl clafs to be double, 



A. 



