LOCATION.--α Persei lies on a line drawn from β to γ Andromedæ, and is about 9° from the latter. The most striking feature in Perseus is the so-called "segment of Perseus," a curve of stars beginning about 12° below Cassiopeia, and curving toward Ursa Major. Note the famous variable Algol the Demon star. It represents the Medusa's head which Perseus holds in his hand. It varies from the second to the fourth magnitude in about three and one-half hours, and back again in the same time, after which it remains steadily brilliant for two and three-quarters days, when the same change recurs. Algenib and Algol form with γ Andromedæ, a right-angled triangle. Note a dull red star near Algol, and a pretty pair just above Algenib. An opera-glass reveals much that is worthy of observation in this region of the sky. It has been said of the clusters between Cassiopeia and Perseus that they form the most striking sidereal spectacle in the northern heavens. They are visible to the naked eye. Algenib never sets in the latitude of New York, just touching the horizon at its lower culmination. It is estimated that Algol is a little over a million miles in diameter, η has three faint stars on one side nearly in a line, and one on the other--a miniature representation of Jupiter and his satellites. Algol, when on the meridian of New York City, is only one tenth of a degree from the zenith point. This remarkable variable has a dark companion star revolving near it obscuring its light in part from us at stated intervals. By means of the spectroscope the speed diameter and mass of this invisible star has been reckoned. [Illustration: PERSEUS] PISCES (pis´ēz)--THE FISHES. (Face Southeast.) LOCATION.--This constellation is represented by two fishes each with a ribbon tied to its tail. One, the Northern Fish, lies just below β Andromedæ,--the other, represented by the circlet, is just below Pegasus. The ribbons, represented by streams of faint stars, from a "V" with elongated sides, and terminate in the star Al Rischa, The Knot. Below ω, and to the east of λ the spot marked (*) is the place which the sun occupies at the time of the equinox. It is one of the two crossing places of the equinoctial, or equator, of the heavens, and the ecliptic, or sun's path. Below Pisces is Cetus, the Whale. Pisces is thought to have taken its name from its coincidence with the sun during the rainy season. Three distinct conjunctions of Jupiter and Saturn took place in this constellation in the year 747 of Rome. Pisces was considered the national constellation of the Jews, as well as a tribal symbol. In 1881, Jupiter, Saturn, and Venus were grouped together in Pisces. The Circlet is a very striking group forming a pentagon. The glass reveals two faint stars in addition, making the figure seven-sided or elliptical in form.