components are a fourth magnitude star accompanied by a distant double companion which is a binary (or revolving double star), and accompanies the bright star in its flight through space. There are two other faint and distant companions which do not partake in the motion of the ternary star. In the year 1864 the bright star was situated to the east of a line joining these faint companions, but owing to its large proper motion it is now to the west of them. In the case of the triple star Struve 1516, one of the companions, which was to the west of the primary star in 1831, is, owing to the proper motion of the bright star, now to the east of it. Prof. Asaph Hall has found a parallax for 40 Eridani of 0.223 of a second. This, combined with the observed proper motion, indicates an actual velocity of about 54 miles per second. The star Mu Cassiopeiæ has also a large proper motion. This star, about 4,000 years ago, must have been close to Alpha Cassiopeiæ, and might have been so seen by the ancient astronomers. The proper motion of the bright star Arcturus is so considerable that in the course of about 30,000 years it will be near the equator, and about 10° to the north of the bright star Spica, from which it is at present separated by over 30°. These motions are of course those which take place across the face of the sky. There are, however, motions in the line of sight--both toward and from the eye--which have of late years been revealed to us by the spectroscope, that wonderful instrument of modern scientific research, by the aid of which several new metals have been discovered, and which has been found so useful in chemical analysis, and even in the manufacture of steel by the Bessemer process. Some years since, Dr. Huggins, the eminent spectroscopist, found that the bright star Sirius, "the monarch of the skies," was receding from the earth at the rate of about 20 miles a second. Later observations at Greenwich Observatory showed that this motion was gradually diminishing, and within the last few years it has been found that the motion of recession has been actually changed into a motion of approach, showing that this giant sun is probably traveling in a mighty orbit round some as yet unknown center of gravity. From a consideration of stellar proper motions, it has been concluded that the sun--and therefore the whole solar system--is moving through space. Recent investigations make the velocity of translation about 19 miles per second (30 kilometers). The Greenwich observations place the "apex of the solar motion" (as the point toward which the sun is moving is called) between Rho and Sigma Cygni, while Dr. Huggins' results fix a point near Beta Cephei. Both these points are near the Milky Way.