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"Any two colors standing opposite each other are complementary to each other. If such colors are blended, the resultant is white light; if any two alternate color are blended, the resultant will be the color that appears between them in the figure." — Avery, 1895

Complementary color wheel

"Any two colors standing opposite each other are complementary to each other. If such colors are blended,…

A diagram of action of diffraction grating.

Diffraction grating

A diagram of action of diffraction grating.

"Make a 'Newton disk', painting the prismatic colors in proper proportion as indicated." — Avery, 1895

Newton disk

"Make a 'Newton disk', painting the prismatic colors in proper proportion as indicated." — Avery,…

"...a tube with a slit at the further end through which the light enters, and at the other end a collimating lens which brings the rays into a parallel beam (the slit is formed between two parallel edges the distance between which can be varied at will)..." —Whitney, 1889

Prism Spectroscope from the Late 19th Century

"...a tube with a slit at the further end through which the light enters, and at the other end a collimating…

"Solar Spectrum.—If a ray, proceeding from the sun, be admitted into a darkened chamber, through an aperture in the window shutter, and allowed to pass through a triangular shaped piece of glass, called a prism, the light will be decomposed, and instead of a spot of white, there will be seen, on the opposite wall, a most brilliant display of colors, including all those seen in the rainbow." —Comstock, 1850

Solar Spectrum

"Solar Spectrum.—If a ray, proceeding from the sun, be admitted into a darkened chamber, through…

"C. Collimator; P, center of group of prisms; T, telescope; s, slit through which the ray of light enters, R, ray on its progress through prisms to telescope."—Finley, 1917

Spectroscope

"C. Collimator; P, center of group of prisms; T, telescope; s, slit through which the ray of light enters,…

"...an instrument which gives a spectrum when the source of the light is in a straight line with the eye—that is, which gives dispersion without deviation—is called a direct vision spectroscope..." —Whitney, 1889

Direct Vision Spectroscope

"...an instrument which gives a spectrum when the source of the light is in a straight line with the…

"A spectrum of sunlight is crossed by dark lines, many hundreds of whcih have been counted and accurately mapped. The more conspicious of these dark lines are distinguisged by letters of the alphabet. A few of these dark lines in the solar spectrum are due to absorption in the earth's atmosphere, but by far the greater number originate in the selective absorption of the solar atmosphere itself." — Avery, 1895

Visible spectrum

"A spectrum of sunlight is crossed by dark lines, many hundreds of whcih have been counted and accurately…