Duff, A. Wilmer (Alexander Wilmer), b. 1864, ed, Guthe, Karl Eugen, 1866-1915, Hallock, William, 1857-1913, Lewis, E. Percival (Exum Percival), 1863-1925, Goodspeed, Arthur W. (Arthur Willis), b. 1860, Carman, Albert Pruden, b. 1861, McClung, Robert Kenning, 1874- · Philadelphia, P. Blakiston's Son & Co · leaf 404
it is evident that the princi-pal focal distances are dif-ferent for different colors,being less for violet than forred (Fig. 263). There is noway to remedy this defect ina single lens, but it may begreatly reduced by a suitable combination of lenses. 453. Achromatic Combinations. By combining two… … r IG. 264. bined to give deviation without dispersion (Fig. 264),lenses are used, for each color If two - + = / /. / if the lenses are in contact. If we wish to combine the two colorscorresponding to the C and F lines, / must be the same for both. 388 LIGHT. If Up and Jif! be the refractive indices…
Physics
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