They saw and named Alcor, thousands of years before telescopes were invented, and long before there were any books to help them.
Alcor (al´-kôr), g Ursæ Majoris, "the cavalier" or "the rider."
Alcor is indeed distant from Mizar by about one-third the apparent diameter of the moon, yet no one would think so!
Just above it is a very small star that astronomers call Alcor, or the rider.
Its distance is a little over half that between Mizar and Alcor.
To be able to see Alcor with the naked eye means that one has excellent eyesight.
The naked eye perceives near it a smaller star, named Alcor.
A person with good eyesight can see quite near to it a fifth magnitude star, known under the name of Alcor.
A subset of ALGOL.
[Sammet 1969, p. 180].