One of the most remarkable features of the universe is that every so-called fixed star is moving forward on an undeviating path which, so far as we.can yet determine, is a straight line. Nothing is better calculated to give us an idea of the extent of the universe than the contrast between the speeds as we observe them from the earth. The actual speed is enormous when compared with any that we can produce by artificial means. The speed of a shot from the most powerful gun can scarcely, if at all, exceed half a mile per second. But if the motion of any star is as slow as one mile a second, it is only in very rare and extraordinary cases.
The average speed of the stars is about 20 miles a second; and this motion, it must be remembered, is not, so far as determined, motion round and round in an orbit, but a straight ahead motion, never relaxing and never swerving. Almost every star, there fore, travels hundreds of millions of miles every year, century after century. And yet so slow do the motions appear to us that the naked eye can see no change in the configuration of the constellations during a period of thousands of years.
A remarkable instance of this kind is afforded by Arcturus, " which is, so far as we know, one of the swiftest moving stars in the heavens. It seems quite certain that its speed exceeds a hundred miles eaoh second of time and it may be much greater. And yet if Job could come again to life aud study the constellation Bootis, in which Arcturus is situated, he would scarcely notice any change in its appearance.
There is not a star in the constellation Orion moving so fast that any change would be noticed by the naked eye in 100,000 year. Every star in the heavens appears in the same position when observed night after night. There are very few in which the astronomer can detect any motion by one year of observations.
Accurate determinations of position commenced with the observations of Bradley in the eigthteenth century who determined the position of more than 3000 of the brighter stars. Since his time the position of several hundred thousand stars have been accurately fixed. Yet so small is the apparent proper motion in most cases that it has been actually detected in the case of only a few thousand stars. Even now there are scarcely a hundred stars of which the motions are known to exceed one second in a year. To understand what this means we must reflect that it would take a good eye to see that two stars in the sky, 200 seconds apart, were not a single object.
Had it not been for the great precision of the telescopic determination, astronomers would not have known to this day that any star in the heavens had moved from the place which it occupied in the time of Ptolmy, 1800 years ago. The star , Z. C 5243, if it were to continue its course round the sky without ever stopping, would take more than 140,000 years to make the circuit of the heavens and the actual speed of this star is known to be about 100 miles per second. - "The Mining World."