HELTER-SKELTER FLIGHT OF THE STARS 323 



Twenty years later Herschel made another attempt, with 

 seemingly more reliable data. It is evidence of the somewhat 

 speculative character of his ideas, that in his second trial he 

 seems to have gone wider than in the first. The exact point 

 can hardly be said to have been established even yet. We 

 have now clearly determined proper motions of hundreds of 

 stars, where Herschel had less than a score. A century or more 

 of observation, comparing, trying out, has served only to 

 confirm, broadly, Herschel' s earlier results. It may be that 

 the stellar apex, as he called it, towards which we are moving, 

 lies in the adjacent constellation of the Lyre rather than in the 

 outstretched arm of the Greek god. It is a question of but a 

 few degrees ; either way the vital fact is that our solar system 

 does move. The proof of this was Herschel's work. 



The direction of this translatory motion appears to be at an 

 angle of about sixty degrees to the plane of the ecliptic, in which 

 we move about the sun. The result of this is to cause the earth 

 to describe in tlte heavens, a spiral path. It might crudely be 

 illustrated by a bed-spring leaning over to one side. It is 

 perhaps worth noting that this corkscrew flight of the earth 

 does not produce a motion tending progressively to turn the 

 heavens upside down as some muddled minds have conceived. 



Herschel made more than one attempt to determine the 

 velocity of solar motion ; obviously the available data were 

 scant. It is of some interest that his conclusion was that " we 

 may in a general way estimate that the solar motion can certainly 

 not be less than that which the earth has in her annual orbit." 

 This is nineteen miles a second. The latest calculations do not 

 vary greatly from this figure. For a time it was supposed that 

 the sun was careening through space with a rush ; some estimates 

 put it as high as a hundred and fifty miles per second. It now 

 seems likely that it is not much more than ten or fifteen miles, 

 somewhere probably between these two. In this view the 

 annual displacement of the solar system is a little more than 

 double the diameter of the earth's orbit, or only about a tenth 

 or fifteenth part of the diameter of the system itself. 



Obviously if the stars were " fixed " it would require an enor- 

 mous range of time before this displacement would be sufficient to 

 cause any appreciable difference in the appearance of the firma- 

 ment. So, too, it will be a long time before we shall be able to 

 determine the larger question as to whether the motion of the 



