Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 446
Fif;. 188.—•Comparison rii.siii, .showing the path of the Kay. The heliostat is a mirror, mounted on an axis, whichmoves at the same rate as the sun appears to travel, sothat wherever the sun is, the reflector, once adjusted,automatically throws the beam into the instrument, so … Fig. 189.—Coiiivarisaii Pri-sni ti.xed in the Slit. that the light of the moving sun can be observedwithout moving the spectroscope. An average solar spectrum is thus obtained, and, bymeans of a prism over one-half of the slit, it was quitepossible for Kirchhoft and Bunsen to throw in a spec-trum…
Astronomy · Telescopes
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