Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 107
Andnow we take away the crown glass and place in its steada prism of flint glass inverted ; the ray in this instanceis deviated less, but there is an equal amount of colour-ing at d. If now we use both prisms, acting in opposite 14 2 «4 STARGAZING : PAST AND PRESENT. [book n. directions, we shall… … ilG. 44.—Diagram Explaining the Formation of an Achromatic Lens. A, crown-glass prism ; B, flint-glass prism of less angle, but giving the same amountof colour ; c, the two prisms combined, giving a colourless yet deviatedband of light at d. shall pass through both. The addition of this prismof…
Astronomy · Telescopes
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