Mr. Goodricke’s Obfervations of a Variable Star. 49 
My firft obfervation was OCh 19, 1784; and as I .wifhed to 
eftablilh the feverai points of the variation with as great accu- 
racy as the nature of the fubjeft will admit of, I have delayed 
fending this account till now ; but as obfervations made through 
fo long an interval of time muft be very numerous, and would 
only fwell this paper to an unneceffary length, I have in the 
following feries formed a fele&ion, chiefly of thofe that were 
made under the moft favourable circumftances ; and I muft 
add, that none of thofe that are omitted contradict the refults. 
From this feries I have fettled, that the ftar has a periodical 
variation of 5 d. 8 h. 37^, during which time it undergoes the 
following changes : 
1. It is at its greateft brightnefs about one day and thirteen 
hours. 
2. Its diminution is performed in about one day and eighteen 
hours. 
3. It is at its greateft obfcuration about one day and twelve 
hours. 
4. It increafes in about thirteen hours. 
When it is in the firft point it appears as a ftar of between 
the fourth and third magnitude ; but its relative brightnefs 
does not feem always to be quite the fame, being fometimes 
between £ and 1 Cephei, and fometimes only equal to, or fome- 
thing lefs than, 1 Cephei, or between £ Cephei and 7 Lacertae. In 
the third point it appears as a ftar of between the fourth and 
fifth magnitude, if not nearer the fifth ; and its relative bright- 
nefs is as follows : nearly equal to g and £ Cephei, and confi- 
derably lefs than 7 Lacertae. 
The relative brightnefs and magnitude of thofe ftars to which 
the variable one was compared, is as follows : % Cephei, the 
brighteft, is between the third and fourth magnitude ; t Cephei, 
Vol. LXXVI. H the 
