i60 PHILOSOPHICAL TRANSACTIONS. [aNNO 1784. 



/. On the Variation of Light in the Star Algol. By Sir Henry C. Englejield, 

 Bart., F.R.S. Anno 1784, Vol. 74, p. 1. 



Sir H. first looked out at midnight, July 2, 1783, and readily found the star, 

 though hardly visible to the naked eye from the vapours near the horizon. It ap- 

 peared much larger than the f , and full as large again as the ■*, also in the field 

 at the same time. At 12~ h . he looked again, and saw but little difference, as 

 Algol was then also evidently much brighter than j. At that time he faintly per- 

 ceived it with the naked eye. At l h 10 m the star was but very little larger than 

 f, the diminution having gone on most rapidly in the interval between the last 

 two observations. Though higher above the horizon it was much less (if at 

 all) visible to the naked eye. At l h 35 m it was diminished, though but little, 

 since the former observation. It was still however a very little larger than f, but 

 not at all visible to the naked eye. At 2 h it was scarcely at all altered from the 

 last observation ; but, if any thing, seemed recovering its light. 



The fact of the diminution of Algol is however fully confirmed, if confirma 

 tion was wanting, by this observation, and the accuracy of the period fixed by 

 Mr. Goodricke ascertained, as the phenomenon was certainly within half an hour 

 of the time fixed by Mr. Goodricke, which, divided on 8 periods, gives only an 

 error of 4 minutes on the length of it ; and a nearer coincidence is not to be ex- 

 pected in a matter of this nature, where estimation is the only means of deter- 

 mining the brightness, and two persons can hardly agree within a few minutes, 

 from the difference of sight. 



77. and III. Observations on the Obscuration of the Star Algol, by Pa/itch, a 

 Farmer. Communicated by the Count de Bruhl, F. R. S. p. 4. 



Palitch, a farmer of Prolitz, a village in the neighbourhood of Dresden, saw 

 the greatest obscuration of Algol on Sept. 12, at 8 o'clock, p.m. On Oct. 2d 

 and 5th, he observed the same phenomenon again. On the 5th the greatest 

 diminution of that star's light happened some minutes before 7, when he judged 

 it nearly of the size of a star of the 4th magnitude : it continued increasing in 

 brightness till a quarter past 10 in the evening, at which time it had entirely re- 

 covered its usual brilliancy and size. 



Oct. 20th, he saw Algol nearly at its greatest obscuration, at 3 o'clock in the 

 morning. Oct. 22, near 12 p. M. he observed it again in the same state. Oct. 

 25, at about Q p. m. it appeared to him like a star of the 3d magnitude. He was 

 prevented by clouds from making long observations ; but as all those he has had 

 opportunities to make, indicate a period somewhat longer than that of 2 days 

 20 h 51 m , he is inclined to think that 2 d 20 h 52 m , will come very near the 

 truth. 



