196 
attained a maximum about the 25th of October. Its magni- 
tude at minimum was 11 3, and at maximum 8'9, the range 
of variation being therefore 2’4 magnitudes. As the ratio of 
light employed in determining the magnitudes is 2'512, it 
follows that the brightness of the new variable is nine times 
greater at maximum than at minimum. The observations 
made since the 28th of July last, compared with those of 
August 19th, 1859, and June 18th, 1860, indicate a period 
of about four months. 
As two telescopic variables had been previously discovered 
in Aquila , the new variable will, according to Professor 
Argelander’s system of nomenclature, be denoted by the 
letter T. 
Taking the naked-eye star p Aquilce, of the fifth magni- 
tude, as a point of departure, the small chart annexed to 
this communication will enable observers whose telescopes 
are not mounted equatorially to find the new variable without 
difficulty. The magnitudes of the comparison stars are : — 
a— 9'2. G?=i0’4. 
5=9-4. e=ll-0. 
c=l(H. /=12-0. 
These magnitudes have been determined photometrically 
by means of Mr. Brothers’s “ Iris Diaphragm.” I may 
however remark that the results for the star f have been 
rather discordant, and it may therefore prove to be slightly 
variable. It is very near the place of Argelander’s No. 
4077, and may probably be the star which he observed 
and which he estimated to be of the 9'4 magnitude. The 
place of T Aquite brought up to 1865 is 20h. 5m. 25'4s. + 
15°-13-4'. 
