Scientific amusements . the surface of the box; fasten a farthing.; If you gazeat these two pieces of money through- a small, circularhole in a piece of cardboard (as in Fig. 73), you will notbe able to distinguish one coin from the other. Theywill both appear the same size. lJlK&lSi^lSJ^^CE OF IMPRESSIONS OF THE RETINA. 87 Of course the distance at which the coin^ must beplaced will depend upon the powers of vision of thespectator. It is as well to fix the cardboard screen, andthen move the box farther or nearer, as may be time will come when the two coins will appear ofequal size
Scientific amusements . the surface of the box; fasten a farthing.; If you gazeat these two pieces of money through- a small, circularhole in a piece of cardboard (as in Fig. 73), you will notbe able to distinguish one coin from the other. Theywill both appear the same size. lJlK&lSi^lSJ^^CE OF IMPRESSIONS OF THE RETINA. 87 Of course the distance at which the coin^ must beplaced will depend upon the powers of vision of thespectator. It is as well to fix the cardboard screen, andthen move the box farther or nearer, as may be time will come when the two coins will appear ofequal size; but by gradually lessening, the distance thefarthing will actually appear larger than the experiment demonstrates that the eye under theconditions indicated is unable to appreciate the distancebetween two objects. By a similar phenomenon themoon, when viewed thi^ough an astronomical telescope,appears smaller than it looks to the unaided eye, whileas a matter of fact it is magnified by the
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Keywords: ., bookcentury1800, bookdecade189, booksubjectscientificrecreations
