The elements of optics; designed for the use of students in the university
James Wood
Paperback
(RareBooksClub.com, March 6, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1801 Excerpt: ...the image upon the retina is inverted with respect to the object; and if, by any means, the image of an erect object, be erect upon the retina, that object appears inverted. 240. It has been objected, that if the images upon the retina be inverted, external objects ought to appear inverted. To which it may be answered, that experience,; I-. 1... alone If the outer coat be taken from an ox's eye, whilst it is warm, the images of external objects are observed to be inverted upon the retina.: alone teaches us, what situation of the external object: corresponds to a particular impression upon the retina 5 nor is it of any consequence what that impression is, or in what manner it is made; but whenever the fame effect is produced upon the organ, we expect to find the fame external object, and in the situation to which our former experience directs us. 241. If the point P move along the line P2/?, from the right to the left, the image p moves from the left to the right, upon the retina. And in general, whenever the image, upon the retina, moves from the left to the right, we are led, by experience, to conclude that the object really moves from the right to the left. 242. If the form of the eye, the situation of the Jeveral humours, and their respective surfaces, remain unaltered, it is manifest that those rays only, which diverge from points at a particular distance, can be collected upon the retina. Thus, if the image of 2 be formed exactly upon the Tetina, the image of Sy a point farther from the eye than 3, will-be formed within the eye; therefore, the rays which proceed from this point, will be diffused over some space upon the retina; and, if they are mixed with the rays which diverge from other points in the object, necessary to be distinguished from the for...