Page:Popular Science Monthly Volume 47.djvu/523

Rh power of such an instrument divides the star into two twinkling points. They are about two and a quarter minutes of arc apart, and exceptionally sharp-sighted persons are able to see them divided



with the naked eye. Now take the three-inch telescope with a moderate power, and look at them. Each of the two stars revealed by the opera glass appears double, and a fifth star of the ninth magnitude is seen on one side of an imaginary line joining