splits light from an object into its array of colors and
records a photographic image of that spectrum on a glass
plate. This spectrograph was mounted at the end of the 36-inch
refracting telescope at the Lick Observatory in California.
It was used to photograph the spectra of stars.
spectrograph's prisms spread the light from a star into
a spectrum, and a camera focused the spectrum onto a small
recorded on the plate was a spectrum produced by an electric
arc between two iron electrodes.
astronomer would compare the lines in the star's spectrum
with unshifted lines in the iron arc spectrum to determine
how far the star's lines were shifted toward the blue
or red. This revealed how fast the star was approaching
or moving away.
spectrograph built in 1894
based on a design by W. W. Campbell
Lent by the Lick Observatory