Curiosities of Light and Sight by Shelford Bidwell is a textbook about the awe-inspiring capabilities and the intriguing shortcomings of the eye. Excerpt: "In the present scientific age every one knows that light is transmitted across space through the medium of the luminiferous ether. This ether fills the whole of the known universe, as far at least as the remotest star visible in the most powerful telescopes, and is often said to be possessed of properties of so paradoxical a character that their unreserved acceptance has always been a matter of considerable difficulty. The ether is a thing of immeasurable tenuity, being many millions of times[Pg 2] rarer than the most perfect vacuum of which we have any experience: it offers no sensible obstruction to the movements of the celestial bodies, and even the flimsiest of material substances can pass through it as if it were nothing."
