. Quarterly journal of microscopical science . Hence we may safely assume tliat all small bodies, whethertransparent or opaque, are undistinguishable when held closeto tlie naked eye, in broad day-light, or diffused light of anykind, but that if it were possible to distinguish them while inthis position, they would appear magnified; and moreover,that this may actually be effected in many instances by theartificial contrivances to which we have been endeavouring: todirect attention. Fisr. If a single object be retained in a given position before ascreen, it will intercept the rays emitted f
. Quarterly journal of microscopical science . Hence we may safely assume tliat all small bodies, whethertransparent or opaque, are undistinguishable when held closeto tlie naked eye, in broad day-light, or diffused light of anykind, but that if it were possible to distinguish them while inthis position, they would appear magnified; and moreover,that this may actually be effected in many instances by theartificial contrivances to which we have been endeavouring: todirect attention. Fisr. If a single object be retained in a given position before ascreen, it will intercept the rays emitted from any number ofseparate luminous bodies, or sources of light, situated in frontof it, and so cast as many shadows. In tliis way the shadowsarc vmltiphcd. Tlus if a finger be held within an inch or twoof the wall, and a number of tapers at as many yards, the pencilsof light lioin the tapers crossing the finger in dillerent direc-tions, and being intercepted bv it, an equal number of shadowsare cast on the wall at intervals, related to the position of the POWER OF SHORT SPACES. 35 taper. And if an opening of given shape were substituted forthe opaque object, as many illuminated spaces would be j)ro-jected on the wall instead of the shadows. This is effected on a small scale in the diascope, where smallperforations which admit the light are substituted for thetapers, transparent designs on glass for the object, and theretina of the eye for the screen on the wall. Beautiful combination
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Keywords: ., bookcentury1800, bookdecade1850, bookpublisheroxfor, bookyear1853
