AN APPROACHING STAR.—One of the most beautiful of all stars in the heavens is Arcturus, in the constellation Boötes. In January last the Astronomer Royal communicated to the Royal Astronomical Society a tabulated statement of the results of the observations made at Greenwich during 1883 in applying the method of Dr. Huggins for measuring the approach and recession of the so-called fixed stars in direct line. Nearly 200 of these observations are thus recorded, twenty-one of which were devoted to Arcturus, and were made from March 30 to August 24. The result shows that this brilliant scintillating star is moving rapidly towards us with a velocity of more than fifty miles per second (the mean of the twenty-one observations is 50.78). This amounts to about 2,000 miles per minute, 180,000 per hour, 4,320,000 miles per day. Will this approach continue, or will the star presently appear stationary and then recede? If the motion is orbital the latter will occur. There is, however, nothing in the rates observed to indicate any such orbital motion, and as the observations extended over five months this has some weight. Still it may be travelling in a mighty orbit of many years’ duration, the bending of which may in time be indicated by a retardation of the rate of approach, then by no perceptible movement either towards or away from us, and this followed by a recession equal to its previous approach. If, on the other hand, the 4,500,000 of miles per day continue, the star must become visibly brighter to posterity, in spite of the enormous magnitude of cosmical distances. Our 81-ton guns drive forth their projectiles with a maximum velocity of 1,400 feet per second. Arcturus is approaching us with a speed that is 200 times greater than this. It thus moves over a distance equal to that between the earth and the sun in twenty-one days. Our present distance from Arcturus is estimated at 1,622,000 times this. Therefore, if the star continues to approach us at the same rate as measured last year, it will have completed the whole of its journey towards us in 93,000 years.—_Gentleman’s Magazine._