94 PLEASANT WA YS IN SCIENCE. 



add that the theory of star-drift, on the strength of which 

 the prediction was made, was in effect demonstrated by the 

 result 



The next application of the new method was one ol 

 singular interest I believe it was Mr. Lockyer who first 

 thought of applying the method to measure the rate of solar 

 hurricanes as well as the velocities of the uprush and down- 

 rush of vaporous matter in the atmosphere of the sun. 

 Another spectroscopic method had enabled astronomers to 

 watch the rush of glowing matter from the edge of the sun, 

 by observing the coloured flames and their motions ; but by 

 the new method it was possible to determine whether the 

 flames at the edge were swept by solar cyclones carrying 

 them from or towards the eye of the terrestrial observer, 

 and also to determine whether glowing vapours over the 

 middle of the visible disc were subject to motion of uprush, 

 which of course would carry them towards the eye, or of 

 downrush, which would carry them from the eye. The 

 result of observations directed to this end was to show 

 that at least during the time when the sun is most spotted, 

 solar hurricanes of tremendous violence take place, while 

 the uprushing and downrushing motions of solar matter 

 sometimes attain a velocity of more than 100 miles per 

 second. 



It was this success on the part of an English spectro- 

 scopist which caused that attack on the new method against 

 which it has but recently been successfully defended, at 

 least in the eyes of those who are satisfied only by ex- 

 perimental tests of the validity of a process. The Padre 

 Secchi had failed, as we have seen, to recognize motions 

 of recession and approach among the stars by the new 

 method. But he had taken solar observation by spectro- 

 scopic methods under his special charge, and therefore 

 when the new results reached his ears he felt bound to 

 con(rm or invalidate them. He believed that the apparent 

 displacement of dark lines in the solar spectrum might be 

 due to the heat of the sun causing changes in the delicate 



