SIRIUS, otherwise called eanicula, or the dog-star, is a star of the first magnitude, the brightest in the heavens, and is situated in the constellation of cards major, or the "great dog." It is about 123 billions of miles distant from the earth. See STARS. It has long been known to possess a "proper motion!' (i.e. an independent progressive motion), was for a time believed to be in a straight line. but has now been shown to consist of au undulatory progressive motion on each side of a middle line. This motion was investigated by prof. Peters of the Pulkowa observatory, Russia, on the supposition that its anomalous character was produced by the attraction of sonic unseen neighbor, and his calculations being completed and verified (on this supposition) by 31r. Safford of Washington, the distance of Sirius from the center of gravity of both was determined to be 1495 millions of miles. In Jan., 1862, Mr. Alvan Clark of New York, chancing to observe Sirius through a powerful telescope, detected a minute star (which had never before been observed) situated ht an angular distance of 7" from Sirius repre senting about 4,300 millions of miles, and it is generally believed that this is the disturber in question. By photometric measurement it has been shown, that, supposing the intensity
of the sun's light for unit of surface to equal that of Sirius, it would require400 suns at the distance of Sirius to send us the light which that star does; and our sun at the distance of Sirius would appear less than a star of the sixth magnitude, and be invisible to the naked eye. The Egyptians called this star Sothis, and at oue time its " heliacal rising" (q.v.) was a sure forerunner of the rising of the Nile; while among the Romans it was considered as a star of evil omen, whose appearance above the horizon coincided with (or even caused) the unhealthy and oppressive heats of summer. Hence the origin of the various superstitious regarding the dog days (q.v.), many of which are still current. —The term "dog star" was also applied to Procyon, a bright star in canis minor, whose heliacal rising differs only by a few days from that of Sirius.