T il 
H. Draper— Oxygen in the Sun. 263 
in 1871, though it has been much modified since. It was ob- 
vious that increased light-collecting power and precise equatoreal 
movements were necessary for the modern applications of 
physics to astronomy. More recently still there has been at- 
tached to the same equatoreal stand an achromatic telescope of 
twelve inches aperture made by Alvan Clark & Sons, this being 
particularly intended for solar spectroscopic work. 
oon after the 28-inch Reflector was turned to stellar and 
Pee cue lines at the more refrangible end of the spectrum. 
ch proc , the 2-inch induction 
coil being succeeded by one of six inches, and that in turn by 
a Ruhmkorff coil capable of giving a ge of seventeen inches. 
e battery was eventually superseded by a Gramme dynamo- 
