The most beautiful colour effects may be produced with these diffusion gratings, as we have shown at the Congress of Rheims in 1907. We have a considerable collection of these diffusion gratings, some with very fine lines, giving a very extended spectrum, and others with coarser striations which give a large number of small Spectra.
"The Mechanism of Life"
Stéphane Leduc
Arguing thus, we may legitimately gather from observed phenomena, that something exists, which even though it be not directly within the range of our senses, must certainly be capable of producing such phenomena: just as the perturbations of one planet have revealed the existence of another; and the lines in their Spectra have taught us the chemical constitution of the sun and stars.
"The Old Riddle and the Newest Answer"
John Gerard
122, have Spectra of the solar type, and in general stars of this class are nearer to us than are the stars with Spectra unlike that of the sun.
"A Text-Book of Astronomy"
George C. Comstock