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and then cementing the pieces together at the edges, the 
rings were made permanent. 
He also showed how the parallel bands of colour could be 
imitated by prismatic refraction of white bands of the same 
ratio as to breadth. 
The author then applied these laws to explaining the 
phenomena of the prism. 
He argued that all matter was put in motion by light, 
just as we are sensible that every atom of a body is moved 
by heat. He showed, not only by diagrams but mechani- 
cally, the physical laws by which light was refracted and 
reflected, and expounded, as he considered, the true theory 
of prismatic refraction. 
As — how a ray of light was always refracted towards 
the base of a prism, and how it could not be physically 
otherwise. Then from these laws he concluded — Given 
the molecular vibration of matter, given the dispersion of 
light. 
He consequently arrived at the conclusion that light no 
more passed through glass than does sound. If we could 
withdraw the ether from a glass globe, we could no more 
see through the glass than we could hear through it if the 
air were removed. 
As to the ether being heterogeneous, we do not say the 
atmosphere is heterogeneous because one sound differs from 
another. 
Why should light, then, differ from sound ? Why com- 
pound, when the same uncompounded air can convey as 
great a variety of notes as there are shades or varieties of 
colours ? A prism no more analyses light or the ether in 
