Page 416 - 89 history of astronomy_opt

studied the dispersion of light by a prism.
Admitting the light of the sun through a
narrow slit in a window-shutter, an inverted
image of the slit can be thrown, by a lens of
suitable focal length, on the wall opposite.
If a wedge or prism of glass be interposed,
the image is deflected to one side; but, as
Newton had shown, the images formed by
the different colours of which white light is
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