64 LIGHT SCIENCE FOR LEISURE HOURS. 



star-motions observed and measured by Dr. Hugging, 

 is the amazing velocity with which some of the stars 

 are moving. Astronomers had ascertained that Sirius 

 is moving athwart the line of vision much more rapidly 

 than the sun is travelling through space. But Sirius 

 is so exceptional both in his brightness and in his esti- 

 mated bulk, that his enormous velocity did not appeal- 

 altogether surprising. It did not lead the generality 

 of astronomers to consider that the sun's velocity and 

 the average velocity of the stars had been greatly under- 

 estimated. But now we learn from a method of research 

 which is far more trustworthy than any applied to the 

 measurement of thwart motions, that some of the stars 

 are moving from or towards the earth with a velocity 

 far exceeding that of Sirius. If we take the thwart 

 motion of Sirius at twenty-five miles per second, and 

 his motion of recession at twenty miles (this being the 

 value assigned by the latest and best measurements), 

 we find for this absolute motion the amazing velocity 

 of about thirty-two miles per second. But Dr. Huggins 

 finds that Arcturus is receding from the sun at the rate 

 of 55 miles per second, Vega at the rate of about 50 

 miles, Arided (the chief brilliant of the Swan) at the 

 rate of 39 miles, Pollux 49 miles, and Dubhe of the 

 Great Bear at the rate of fr6m 46 to 60 miles per 

 second. Beside such motions as these, our sun's esti- 

 mated velocity of about 4| miles per second, which had 

 seemed so imposing when it was considered that he 

 bore with him at this enormous rate his whole family 

 of planets, sinks into relative insignificance. We here 



