Recreations in astronomy : with directions for practical experiments and telescopic work (1879)
Warren, Henry White, 1831-1912 · New York : Harper & Brothers · leaf 64
l objects witha telescope and spectroscope we must, in every instance,contract the apertureof the instrument un-til we ^ot only a small ,m of light. In or-der to have the colorsthoroughly dispersed,the best instrumentspass the beam of lightthrough a series ofprisms called a bat-ich one spread- _… … 50 ASTRONOMICAL INSTRUMENTS. spectrum can be examined on the retina of the eye fora screen. In order to still farther disperse the rays,some batteries receive the ray from the last prism at 0upon an oblique mirror, send it up a little to another,which delivers it again to the prism to make its…
Astronomy
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