6
1,682,572
to each other, and an optical wedge mounted within said telescope for sliding movement longitudinally thereof.
16. In an instrument of the character set5 forth, a collimator, a dispersion prism and a telescope having a fixed ocular aperture, fixed against movement relatively to each other, and optical means movable relatively to said telescope to move the beam dispersed by said prism transversely of said ocular 10aperture and bring different portions of the spectrum into coincidence with said aperture.
In testimony whereof I have hereunto set my hand.
Carl. W. Keuffel.
