double-convex

There is a beautiful transparent, double-convex body, about one-third of an inch thick, which looks very much like an ordinary glass lens, and is situated in the eye just back of the pupil.

The Home Medical Library, Volume II (of VI) Kenelm Winslow

One of the humors of the eye; a double-convex body situated in the front part of the eyeball.

A Practical Physiology Albert F. Blaisdell

This was the suggestion to use two plano-convex lenses, placed at a prescribed distance apart, in lieu of the single double-convex lens generally used.

A History of Science: in Five Volumes. Volume IV: Modern Development of the Chemical and Biological Sciences 1904

The old-fashioned double-convex lens used in telescopes became so heavy as its size grew, that it bent perceptibly from its own weight, when pointed at the zenith, distorting the vision; while when it was used upon a star near the horizon, though the glass on edge kept its shape, there was too much atmosphere between it and the observed object for successful study.

A Journey in Other Worlds 1894

The old-fashioned double-convex lens used in telescopes became so heavy as its size grew, that it bent perceptibly from its own weight, when pointed at the zenith, distorting the vision; while when it was used upon a star near the horizon, though the glass on edge kept its shape, there was too much atmosphere between it and the observed object for successful study.

A journey in other worlds A romance of the future John Jacob Astor 1888

"So," he writes, "I took my hatchet, chipped a small piece of ice into the form of a double-convex lens, [Page 33] smoothed it with my warm hands, held it up to the sun, and, as the old man was blind, I kindly burned a blister on the back of his hand to show him I could do it."

Recreations in Astronomy With Directions for Practical Experiments and Telescopic Work Henry White Warren 1871

It had been sifted by passing it through a solution of alum, and through the thick double-convex lens of the lamp.

Fragments of science, V. 1-2 John Tyndall 1856

Fig 5 represents a double-convex lens, Fig. 6 a double-concave, and

American Hand Book of the Daguerreotype 1853

By these it is seen that a double-convex lens tends to condense the rays of light to a focus, a double-concave to scatter them, and a concavo-convex combines both powers.

American Hand Book of the Daguerreotype 1853

If parallel rays of light fall upon a double-convex lens, D D, Fig. 8, they will be refracted (excepting such as pass directly through the centre) to a point termed the principal focus.

American Hand Book of the Daguerreotype 1853