William Tyler Olcott

“ This bright star is Altair in Aquila. It forms with Vega and Deneb an isosceles triangle. Altair is at the apex, about 35 degrees from the other two. A triangle is formed by Vega, Altair, and Ras Alhague, in the Serpent Bearer, which is about 30 degrees west of Altair.
This is a double constellation composed of Aquila and Antinous. Altair is in the neck of the eagle, Alschain in the head of Antinoüs.
When the moon is absent, a rude arrow head can be traced out, embracing almost all the stars in Aquila. ”