t>f a new Vatiable Star,.^ 155 



their change of poiitloii occafioned by the earth's diurnal 

 motion, and that particularly in ftars of a great altitude. 



The magnitudes of the ftars, to which /3 Lyrce was com- 

 pared during the progrefs of its variation, are as follows. 

 /3 Cygni and y Lyrae of the third magnitude ; | and 5 Kerculis 

 of between the fourth and third magnitude ; Herculis is 

 fomething lefs than a ftaf of the fourth magnitude; ^, k, audi 

 ^ Lyr;£ are ftars of between the fourth and fifth magnitude, if - 

 hot nearer the fifth. The relative brightnefs of thefe flats 

 follows the order in which they are fet down. 



Ohfervat'ions of ihe brlghtnefi and magnitude of 13 Lyrae. 



1784, Sept. 10. At 1 1 h. =*=, much lefs than y Lyras; 

 nearly equal to, if not rather brighter than f, x, and S Lyras, 

 and not fo bright as |, ^, and c? Herculis ; between the fourth 

 and fifth magnitude, 



Sept. II. At 8| h. nearly the fame as it was lafl night, if 

 not brighter; indifferent obfervation. 



Sept. ,12. At 8| h. and ph. between the third and fourth 

 magnitude ; lefs than y Lyras, brighter than 5, |, and Her- 

 culis, and much brighter than f, jc, and S Lyrae. Mr. E. 

 Pi GOT T agrees with me nearly. 



Sept. 13, 15, 18, 19, and 20. It was at or near its greateft 

 brightnefs. 



Sept. 23. At yi h. it was nearly eqjual to ^, x, and Lyrae, 

 and much lefs than ^, 9, and HercuHs. 



At io| h. the air being extremely clear, Icompared it more 

 attentively to the neighbouring ftars, and found it as follows : 

 rather a little brighter than $, a little lefs than f, and rather 



X 2 lefs 





