of a new Variable Star, rq^ 



A fpherical form, or a large body revolving round it, or witii 

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

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

 je61:u res with regard to Algol be attended with difficulties^ fome 

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

 9; Antinoi- 



Thofe perfons who are accuftomed to examine the fl:ars atten- 

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

 do not always perfe6tly agree in our obiervations ; thefe fmall 

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

 afcertained with the naked eye, w^iich has often made me la- 

 ment,'^ we had not fome contrivance for determining their relative 

 brightnefs, and even I attempted feveral methods, but did not 

 purfue them with fufficient attention and diligence to obtain 

 any fatisfi6lory refults ; neverthelefs I (hall juft mention them^ 

 as perhaps fomebody elfe may overcome thofe difficulties, 

 which to me appeared fo Ytxy confiderable. ' 



1. In 1778 I had fmall pieces of fine glafs ftained with dif- 

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

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

 ilars of different brightnefs ; and thu-s I obferved fome of the 

 ftars and planets* 



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

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



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

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

 ti telefcope till they become invifible ; this is performed by- 

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

 ©f focal diftance being previoufly determined, the brighter tlie 

 itar the greater length of tube mufl be (lid either in or out to 

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



2-. tudes. 



