A spectrograph 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.

• The spectrograph's prisms spread the light from a star into a spectrum, and a camera focused the spectrum onto a small photographic plate.
• Also recorded on the plate was a spectrum produced by an electric arc between two iron electrodes.
• The 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.

Brashear spectrograph built in 1894
based on a design by W. W. Campbell
Lent by the Lick Observatory