Fifth book of lessons for the use of schools . eacup, andthe teacup at such a distancefrom the eye that the rim shallhide the shilling, it will becomevisible by filling the cup withwater. In the first instance, therays reflected by the shilling aredirected higher than the eye, butwhen the cup is filled with water, they are refracted byits attraction, and bent downwards at quitting it, so asto enter the eye. When the shilling becomes visible bythe refraction of the ray, you do not see it in the situ-ation which it really occupies, but an image of it higherin the cup; for as objects always appea
Fifth book of lessons for the use of schools . eacup, andthe teacup at such a distancefrom the eye that the rim shallhide the shilling, it will becomevisible by filling the cup withwater. In the first instance, therays reflected by the shilling aredirected higher than the eye, butwhen the cup is filled with water, they are refracted byits attraction, and bent downwards at quitting it, so asto enter the eye. When the shilling becomes visible bythe refraction of the ray, you do not see it in the situ-ation which it really occupies, but an image of it higherin the cup; for as objects always appear to be situatedin the direction of the rays which enter the eye, theshilling will be seen in the direction of the refractedray at B. The manner in which an oar appears bent inwater is a similar effect of refraction. When wesee the bottom of a clear stream, the rays which it re-flects, being refracted in their passage from the waterinto the air, will make the bottom appear more elevatedthan it really is, and the water will consequently appear. 349 FIFTH BOOK. more shallow. Accidents have frequently been occa-sioned by this circumstance; and boys who are in thehabit of bathing should be cautioned not to trust to theapparent shallowness of water, as it will always provedeeper than it appears. The refraction of light prevents our seeing the hea-venly bodies in their real situation. The light theysend to us being refracted in passing into the atmosphere,we see the sun and stars in the direction of the refractedray. If the sun were immediately over our heads, itsrays falling perpendicularly on the atmosphere wouldnot be refracted, and we should then see it in its truesituation. To the inhabitants of the torrid zone, wherethe sun is sometimes vertical, its rays are then not re-fracted. There is, however, another obstacle to see theheavenly bodies in their true situation, which affectsthem in the torrid zone as well as elsewhere. Light isabout eight minutes and a half in its passage f
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