Jones, H. Spencer (Harold Spencer), 1890- · London E. Arnold & co. · leaf 340
from shght differences in the sensitivities of the platesor in their treatment during development. The principle of themethod by which photographic magnitudes are determined isto give one exposure on the field of stars under investigationand then a second exposure in which the intensities of the… … (a) Parallel wire Diffraction Gratinc uskd at thp;KovAi. Observatory, Greenwich. f ■ ,1 1 i m ^^^^^^1 PlMAmK:^<* - ^ (b) Star images obtainkh with Grating. THE STARS 295 easily effected by reducing the aperture, the light falling on theplate being then reduced proportionally to the area of…
Astronomy
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