Spectrograph is the larger of the two it becomes necessary to adjust the object glass 0 1 farther C Ia from the stellar spectrograph.
The narrow tongues of the silvered surface will now reflect corresponding parts of the star-spectrograph, and will obliterate corresponding parts of the solar spectrograph - as shown in figs.
How the stars really move in space, and how the sun travels among them, can be ascertained only with the aid of materials collected by the spectrograph, which has now fortunately been brought to comply with the arduous conditions of exactitude requisite for collaboration with the transit instrument and its allies, the clock and chronograph.
Then if the prism P4 is cemented to P3, a sharp image of such lines of the solar spectrograph as are visible in the field of view will be seen in the eyepiece.
Then the lines of the stellar spectrogram would be seen in focus of the eyepiece and the image of the solar spectrograph would be obliterated.