Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 504
tends from the greenpart of the spectrum right into that part of the spec-trum called the ultra-violet. Of course it had to beput together from different pictures, liecause there is a dif-ferent length of exposure required for the different parts ;the exposure of any particular part of the… … I 1 482 STARGAZING : PAST AND PRESENT. [book vi. require to be exposed for eight minutes, and at the lineH, which is further away from the luminous part of thespectrum than G, there the exposure requisite would betwo or three minutes. In order, to obtain a photograph of the average solarspectrum,…
Astronomy · Telescopes
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