Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 146
ring the per-formance of the object-glass from surfaces so arrangedthan if the curves were deep. COAP. X.] PRODUCTION OF LENrsr:S AND SPECULA. 123 But whatever curves he chooses he goes to work so thatthe spherical aberration of the compound lens shall beeliminated as far as possible, and the… … Fig. 64.—Images of planet produced by short and long focus lenses of the sameaperture giving images of difierent size, but with the same amount ofcolour round the edges. This matter requires a somewhat detailed treatmentin order that it may be seen how the four surfaces towhich reference has been…
Astronomy · Telescopes
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