346 - Stir John Lubbock’s Address. 
opinion, indicate the presence of hydrogen: one of them agrees 
in position with a line characteristic of nitrogen. 
ut spectrum analysis has even more than this to tell us. 
The old methods of observation could determine the move- 
ments of the stars so far only as they were transverse to us;_ 
they afforded no means of measuring motion either directly 
towards or away from us. Now Déppler suggested in 1841 
that the colors of the stars would assist us in this respect, be- 
cause they would be affected by their motion to and from the 
earth, just as a steam-whistle is raised or lowered as it ap- 
proaches or recedes from us. Everyone oe observed that if a 
train whistles as it passes us, the sound appears to alter at the 
moment the engine goes by. This arises, of course, not from 
any change in the whistle itself, but because the number of 
vibrations which reach the ear in a given time are increased by 
the speed of the train as it approaches, and diminished as it 
recedes. So, like the sound, the color would be affected by 
such a movement; but Déppler’s method was practically imap- 
plicable, because the amount of effect on the color would be 
utterly insensible; and even if it were conberWiae the method 
which is due to hydrogen. noe if Sirius was dere teres or 
rather if it retained a constant distance from the earth, the line 
in succession to Sir G. “Airy, who has long occupied the post 
with so much honor to himself and advantage to science 
To examine the spectrum of a shooting star would seem even 
more difficult; yet Alexander Herschel has succeeded in doing 
so, and finds that their nuclei are — solid bodies : 
e has recognized the lines of potassium, sodium, lithium and 
other substances, and considers that the shooting stars are 
