Vega was the first star to be photographed, in 1850. It is visible at some hour every clear night, and has been called the arc-light of the sky. Its light has the bluish-white hue that suggests "a diamond in the sky." The spectroscope reveals that Vega is a star probably only in its infancy, as hydrogen is its predominating element. [Illustration: LYRA] CYGNUS (sig´-nus)--THE SWAN, OR THE NORTHERN CROSS. LOCATION.--Deneb, the brightest star in Cygnus, is at the top of the cross, and a little over 20° east of Vega. It forms a triangle with Vega and Altair in Aquila--Altair being at the apex, about 35° from Deneb and Vega. β Cygni is at the base of the cross, and a line drawn from Vega to Altair nearly touches it. It is a beautiful colored double for a small telescope. Note "61," one of the nearest stars to us. It was the first star whose distance was measured (by Bessel in 1838). It is a double star and 10.4 light years distant. The cross is nearly perfect and easily traced out. It lies almost wholly in the Milky Way. Note "The Coal Sack," one of the dark gap in the Milky Way. Cygnus contains an unusual number of deeply colored stars and variable stars. ο Cygni has a sixth-magnitude companion, and γ is in the midst of a beautiful stream of faint stars. This region is perhaps richer than any similar extent in the heavens. An opera-glass will reveal many of its beauties. Herschel counted 331,000 stars in an area of only 5° in Cygnus. [Illustration: CYGNUS] AQUILA (ak´-wi-lä)--THE EAGLE, AND ANTINOÜS. (Face Southeast.) LOCATION.--Half-way up the sky in the Milky Way, you will see three stars in a line, the middle one much brighter than the other two. This bright star is Altair, in Aquila. It forms with Vega and Deneb an isosceles triangle. Altair is at the apex, about 35° from the other two. A triangle is formed by Vega, Altair, and Ras Alhague, in the Serpent Bearer, which is about 30° west of Altair. This is a double constellation composed of Aquila and Antinoüs. Altair is in the neck of the Eagle, Alschain in the head of Antinoüs. When the moon is absent, a rude arrowhead can be traced out, embracing almost all the stars in Aquila. η is an interesting variable star, changing from magnitude 3.5 to 4.7 and back again within a period of 7 days 4 hours 12 minutes. Altair rises about 8° north of the exact eastern point on the horizon. In A.D. 389 a wonderful temporary star flashed out near Altair that equalled Venus in brightness and vanished within three weeks' time. [Illustration: AQUILA ANTINOÜS] DELPHINUS (del-fi´-nus)--THE DOLPHIN, OR JOB'S COFFIN. (Face Southeast.)