Fifth book of lessons for the use of schools . bove proceed below, those fromthe right go to the left, those from the left towards theright; thus every object is represented in the picture asoccupying a situation the very reverse of that which itdoes in nature, excepting the flower-pot, E F, whichthough its position is reversed, does not change its OPTICS. 33; gituation in the landscape, for being immediately in frontof the aperture, its rays fall perpendicularly upon it,and consequently proceed perpendicularly to the wall,where they delineate the object. It is thus that thepicture of objects
Fifth book of lessons for the use of schools . bove proceed below, those fromthe right go to the left, those from the left towards theright; thus every object is represented in the picture asoccupying a situation the very reverse of that which itdoes in nature, excepting the flower-pot, E F, whichthough its position is reversed, does not change its OPTICS. 33; gituation in the landscape, for being immediately in frontof the aperture, its rays fall perpendicularly upon it,and consequently proceed perpendicularly to the wall,where they delineate the object. It is thus that thepicture of objects is painted on the retina of the pupil of the eye, through which the rays of lightenter, represents the aperture in the window-shutter;and the image delineated on the retina is exactly similarto the picture on the wall. The different apparent dimensions of objects, at dif-ferent distances, proceed from our seeing, not the objectsthemselves, but merely their image on the retina. Hereis represented a row of trees, as viewed in the camera. obscura; the direction of the rays from the objects tothe image is expressed by lines. Observe that the raywhich comes from the top of the nearest tree, and thatwhich comes from the foot of the same tree, meet atthe aperture, forming an angle of about twenty-fivedegrees; this is called the angle of vision, beingthat under which we see the tree. These rayscross each other at the aperture, and represent the treeinverted in the camera obscura. The dimensions of theimage are considerably smaller than those of the object,but the proportions are perfectly preserved. The upperand lower ra} from the most distant tree, form an angleof not more than twelve or fifteen degrees, and an imageof proportional dimensions. Thus two objects of thesame size, as the two trees of the avenue, form figuresof different sizes in the camera obscura, according totheir distance, or, in other words, according to the angleof vision under which they are seen. In sculptu
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