of a new Variable Star . 135 
spherical form, or a large body revolving round it, or with 
feveral dark fpots or fmall bright ones on its furface, alfo giv- 
ing an inclination to its axis, &e. ; though moft of thefe con- 
jectures with regard to Algol be attended with difficulties, fome 
of them combined do, I think, account for the variation of 
^ AntinoL 
TChofe perfons who are accuftomed to examine the ftars atten- 
tively will not be furprifed to find, that Mr. Goodricke and I 
do not always perfectly agree in our obfervations ; thefe fmall 
differences in the magnitudes of the ftars 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 not 
purfue them with fufficient attention and diligence to obtain 
any fatisfa&ory refults neverthelefs I ftiall juft mention them, 
as perhaps fomebody elfe may overcome thofe difficulties, 
which to me appeared fo very confiderabie. 
r. In 177B I had fmall pieces of fine glafs framed with dif- 
ferent ftiades, which being applied to the eye end of a telefcope, 
I could eafily find what degree of ffiade was requifite to efface 
ftars 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 ftars of the firft magnitude. 
3. A method which pleafed me much, and perhaps may not 
prove unfuccefsful, is, by putting the ftars out of the focus of 
a telefcope till they become invifible; this is performed by v 
drawing the eye-tube of a refraClor either in or out ; the point ; 
of focal diftance being previoufly determined, the brighter the 
ftar the greater length of tube muft be Aid either in or out to 
efface it; thus I was in hopes of determining their magni- 
2' tudes,- 
