ICELAND SPAR • FREE TRANSLATOR.ORG • Definition of Iceland spar

"Iceland spar" Quotes from Famous Books

... as yet contrived and used for optical superimposition is a "double-image prism" of Iceland spar (see Fig., p. 228), formerly procured for me by the late Mr. Tisley, optician, Brompton Road. They have a clear aperture of a square, half an inch in the side, and when held at right angles to the line of sight will separate the ordinary and extraordinary images to the amount of two inches, ...

— Inquiries into Human Faculty and Its Development • Francis Galton

... an impression of four lines in the spectrum of Vega. Then Huggins attacked the subject again in 1876, when the 18-inch speculum of the Royal Society had come into his possession, using prisms of Iceland spar and lenses of rock crystal; and this time with better success. A photograph of the spectrum of Vega showed seven strong lines.[1415] Still he was not satisfied. He waited and worked for three years longer. At length, on December ...

— A Popular History of Astronomy During the Nineteenth Century - Fourth Edition • Agnes M. (Agnes Mary) Clerke

... duplicity in life seems to me at times ineradicable, at times like the confusing of something essentially simple, like the duplication when one looks through a doubly refracting medium. You think in this latter mood that you have only to turn the crystal of Iceland spar about in order to have the whole thing plain. But you never get it plain. I have been doing my halting utmost to get down sincerely and simply my vision of life and duty. I have permitted myself ...

— First and Last Things • H. G. Wells

... symmetry of aggregation, and hence conclude that the line perpendicular to the planes of freezing is a line of no double refraction; that it is, in fact, the optic axis of the crystal. The same remark applies to the line joining the opposite blunt angles of a crystal of Iceland spar. The arrangement of the molecules round this line being symmetrical, the condition of the ether depending upon these molecules shares their symmetry; and there is, therefore, no reason why the wavelength should ...

— Faraday As A Discoverer • John Tyndall