crown glass

noun

1. an optical glass of low dispersion and generally low index of refraction.
2. an old form of window glass formed by blowing a globe and whirling it into a disk.

crown glass

noun

1. another name for optical crown
2. an old form of window glass made by blowing a globe and spinning it until it formed a flat disc

Word History and Origins

Origin of crown glass¹

First recorded in 1700–10

Example Sentences

In making crown-glass, which is used for windows, a slight alteration in the process is observed.

From Project Gutenberg

The focal length of double convex lenses of crown glass is about the same as the radius of curvature of either surface.

From Project Gutenberg

The achromatic lens consists of a double convex lens of crown glass combined with a plano-concave lens of flint glass.

From Project Gutenberg

English crown-glass; excellent quality, but not so white as the last.

From Project Gutenberg

Such a mixture will produce a dull metal, very attractive of moisture: defects to which the French crown-glass also is subject.

From Project Gutenberg