86 PHILOSOPHICAL TRANSACTIONS. [aNNO 1786. 



same. 3. Therefore it may be considered as invisible also during 6 months. 

 4. It is considerably quicker in increasing than in decreasing, perhaps by half. 



Hevelius's 30th Hydrae is the above star ; he marks it of the 6th magnitude. 



The famous Nova of 1604, in Serpentarius. — A full account of this star is 

 given by Kepler, and it seems to have had a similar appearance to the Nova in 

 Cassiopea ; therefore the reflections delivered there need not be again repeated. 



|3 Lyra. — Mr. Goodricke discovered the variation and period of this star, and 

 hopes soon to settle its difi^erent phases with more exactness. In his last account 

 he mentions having first suspected the period to be only of 6 days 9 hours ; such 

 has always been my opinion. 



Nova near the Swans Head of I670. — This star was first seen in December 

 1669 by Don Anthelme; it soon became of the 3d magnitude, and disappeared 

 in 1672, after having undergone several variations. I have constantly looked for 

 it since November, 1781, without success ; had it increased to only the 10th or 

 1 1th magnitude, I should have perceived it, having taken an exact plan of all the 

 surrounding stars. 



u Antinoi. — The variation and period of this star I discovered last year, and 

 communicated an account of it to the r. s. The period, as settled in my former 

 paper, is 7^^ 4*^ 38"^; but for reasons there alleged, it must be much less precise 

 than the following, viz. 7^ 4^ 15*". 



I see no reason to alter materially the other points ; but believe them more 

 exact thus : 40** at its greatest brightness ; Q&^ in decreasing ; SO*' at its least ; 

 36^ in increasing. It also, in every period, seems to attain the same degree of 

 brightness when at its full, and to be equally decreased. 



Fariable in the Swans Neck. — During these 3 years I have observed this star 

 with particular attention, and determined the middle time of its greatest bright- 

 ness very exactly ; whence it is inferred that its period will be found of only 396 

 days 21 hours. 



Particulars of the changes it undergoes are, 1 . When at its full brightness it 

 has no perceptible change for about a fortnight. 1. It is about 3^ months in 

 increasing from the 11th magnitude to its full brightness, and the same in de- 

 creasing. 3. Therefore it may be considered as invisible during 6 months. 4. It 

 does not attain the same degree of brightness at every period, being sometimes 

 of the 5th, and other times of the 7th magnitude. 



Its mean right ascension, computed from my observations, and reduced to 

 Aug. 1, 1783, is 295° 33' 48y^ 



Variable in the Swans Breast. — ^This star was first seen by G. Janson in 160O, 

 and afterwards frequently observed by different astronomers, but with intervals of 

 10 or more years, which is probably the reason why no regularity in its changes 

 has yet been deduced. I have examined minutely the observations made in the 



