30 
HAROLD’S DISCUSSIONS. 
and became a filmy cloud of “ star dust ”—the world 
stuff. 
9. The spectroscope reveals the constitution of all 
the solar bodies to be the same as the earth’s. 
Fig. 11.—Spectroscope. 
The spectroscope is a most wonderful, though, 
when understood, simple instrument invented by two 
German professors, Bunsen and Kirchhoff. It has 
proved of the highest scientific and practical value. 
