Page:Star Lore Of All Ages, 1911.pdf/419

Rh have claimed that Perseus represents David with the head of Goliath, and the Apostle Paul with his sword and book.

The constellation is 28° in length, one of the most extended in the heavens. Its principal stars form a curved line that bears the name of "the Segment of Perseus," a figure that is almost as much of a stellar landmark as the Great Square of Pegasus.

The most interesting star by far that the constellation contains is the variable "Algol," the so-called "Demon Star," or "Blinking Demon."

The variability of this remarkable star was first scientifically noted by Montanari in 1670, but it is tolerably clear that these light variations had been detected long before his day. Indeed the winking of this star, so to speak, probably influenced those who christened it, so that they likened it to the eye of some great demon peering down through space seeking his prey.

Goodricke, in 1782, was the first one to advance the eclipse theory to account for the variations in the light of this star, and since that date it has been under the constant observation of trained observers.

In 1880 Pickering reaffirmed the eclipse theory, and Vogel subsequently proved the theory unquestionably correct by means of that wonderful instrument the spectroscope.

During 2,5 days Algol is constant at magnitude 2.3. It then begins to diminish in brilliance, at first gradually, and afterwards with increasing rapidity to 3.5 magnitude during a period of about nine hours; its total period being stated as two days, twenty hours, forty-eight minutes, and fifty-five seconds.

In accordance with the eclipse theory to account for the variations of light in Algol, it has been proved that this star is accompanied by a great dark satellite as large as our sun, which at regular intervals passes between us and Algol, cutting off a portion of its light. Algol is said to be one million miles in diameter, while the diameter of the satellite is given as eight hundred thousand miles. The distance between