Page:US patent 1682572.pdf/10

 to each other, and an optical wedge mounted within said telescope for sliding movement longitudinally thereof.

16. In an instrument of the character set 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 aperture and bring different portions of the spectrum into coincidence with said aperture.

In testimony whereof I have hereunto set my hand.