Encyclopaedia; or, A dictionary of arts, sciences, and miscellaneous literature; constructed on a plan, by which the different sciences and arts are digested into the form of distinct treatises of . ^y^/.-t ,/ -yy^.H. K,. r^ v^___— — ^^—XT I b:. J/i^rl-Tf. t Part II. OPT Rcflfiaing not fo pleafant; for wliich reafon, die li is ftill vetiiiiied, to enlarge the fcope or area ot the 176 To find the magnifying power of tliis tclcfcope,Ifing mnkiply the focal diftance of the great mirror by the power. diftance of the fmall mirror from the image nex
Encyclopaedia; or, A dictionary of arts, sciences, and miscellaneous literature; constructed on a plan, by which the different sciences and arts are digested into the form of distinct treatises of . ^y^/.-t ,/ -yy^.H. K,. r^ v^___— — ^^—XT I b:. J/i^rl-Tf. t Part II. OPT Rcflfiaing not fo pleafant; for wliich reafon, die li is ftill vetiiiiied, to enlarge the fcope or area ot the 176 To find the magnifying power of tliis tclcfcope,Ifing mnkiply the focal diftance of the great mirror by the power. diftance of the fmall mirror from the image next theeye, and multiply the focal diftance of the Imall mir-ror by the focal diftance of the eye-glafs: then dividethe produifl of the former miiUipllcation by the pro-duct of the latter, and the quotient will exprefs themagnifying power. One great advantage of the refleding tclcfcope is,that it will aJmit ot an eye-glafs ot a much (horterfocal diftance than a refraifting telefcope will ; andconfequendy it magnify lo much the more : forthe rays are not coloured by refledtion from a concavemirror, if it be ground to a true figure, as they areby paflhig through a convex glafs, let it be groundever fo true. The nearer an objefl is to the telefco
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Keywords: ., bookcentury1700, bookdecade1790, bookidencyclopaedi, bookyear1798
