of a new Variable Star, i or 



a fpherical form, or a large body revolving round It, or with 

 feveral dark fpots or fmall bright ones on its furface, alio giv- 

 ing an inclination to its axis, &;c. ; though moil: of thefe con- 

 jectures with regard to Algol be attended with difficulties, fome 

 of them combined do, I think, account for the variation of 

 yi Antinoi. 



Thofe perfons who are accuftomedto examine the flars atten- 

 tively will not befurprifed to find, that Mr. Goodricke and I 

 do not always perfe(5lly agree in our obfervations ; thefe fmall 

 differences in the magnitudes of the flars are very difficult to be 

 afcertained with the naked eye, which has often made me la- 

 ment, .we had not fome contrivance for determining their relative 

 brightnefs, and even I attempted feveral methods, but did nor 

 purfue them with fufficient attention and diligence to obtain 

 any fatlsfa£l:ory refults ; neverthelefs I fhall juft mention them., 

 as perhaps fomebody elfe may overcome thofe difficulties, 

 which to me appeared fo very confiderable. 



1. In 177S I had fmall pieces of fine glafi ftained with dif- 

 ferent (hades, which being applied to the eye end of a telefcope, 

 I could eafily find what degree of fhade was requifite to efface 

 flars of different brightnefs \ and thus I obferved fome of the 

 ftars and planets. 



2. Diaphragms were attempted ; but, befides other diffi- 

 culties, they did not efface flars of the firfl magnitude. 



3. A method which pleafed me much, and perhaps may not 

 prove unfuccefsful, is, by putting the flars out of the focus of 

 a telefcope till they become invifible ; this is performed by 

 drawing the eye-tube of a refra6lor either in or out; the point 

 of focal diflance being previoufly determined, the brighter the 

 ftar the greater length of tube mud be (lid either in or out to 

 efface it ; thus I was in hopes of determining their magni- 



z tudes^ 



