The Photographic art-journal . vacuumprogresses in a perfectly straight line, andwe should, if we looked at a brilliantly il-laminated point—where it possible—undersuch conditions, see it in its true position,the numerous rays coming undisturbed di-rectly to the eye. But all matter, how-ever attenuated it may be, has the propertyof refracting, or bending the ray of light;consequently we do not see the stars intheir true position, owing to the refractivepower of the atmosphere. The most single illustration cf refrac-tion is to allow a sunbeam o, passingthrough, a small hole in the window-shutte
The Photographic art-journal . vacuumprogresses in a perfectly straight line, andwe should, if we looked at a brilliantly il-laminated point—where it possible—undersuch conditions, see it in its true position,the numerous rays coming undisturbed di-rectly to the eye. But all matter, how-ever attenuated it may be, has the propertyof refracting, or bending the ray of light;consequently we do not see the stars intheir true position, owing to the refractivepower of the atmosphere. The most single illustration cf refrac-tion is to allow a sunbeam o, passingthrough, a small hole in the window-shutter of a dark room, to fall upon the surface ofa fluid contained in a glass vessel, b b :instead of proceeding onwa?ds to a. it willbe found to alt^r its course at the surfaceof the fluid, and pass along the line to a substance has clifleient refractivepowers in virtue of its physical constitu-tion ; but a ray of light incident pe»peu-dicularly on a refracting medium, as tieray c, ( Fig. 1) suffers no refraction. If. 1. we float, one upon the other, fluids, &,<?,£?,having different powers of refraction, wea
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectphotogr, bookyear1851
