Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 454
found the brightlines of the vapour to correspond with any particulardark line of the spectrum of the star, he would knowwhether the metal exists at that star or not; so thislittle mechanical arrangement at once tells him whatthere is at the star, whether it be iron or anythingelse. In Figs. 197… … Fia. 199.—Direct-vision Star Spectroscope. (Secchi.) A new optical contrivance altogether has to be usedwhen star spectra are observed. The image of a star is a point, and if focussed onthe slit will of course give only an extremely narrowspectrum ; to obviate this a cylindrical lens is…
Astronomy · Telescopes
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