The new imperial encyclopaedia, or, Dictionary of the sciences and arts : comprehending also the whole circle of miscellaneous literature ... . IL /#• 1 <n) F T I C .H. O RA 14:3 O RA ble object, at which it can be distinctly seen ; iuul let d representits ili^Umte Ironi tlie obiect-glass of tlie instriimei)!. Lei m be themagnifying power of the instrnm-nt ; tliat is, let the visual anglesutJteiKled at the eye by the object wh:n at the distance n, anu view-ed without the instrunn iit, be to the visual angle produced b theinitrunient as 1 ti m Let a be the diameter of the ,and 0
The new imperial encyclopaedia, or, Dictionary of the sciences and arts : comprehending also the whole circle of miscellaneous literature ... . IL /#• 1 <n) F T I C .H. O RA 14:3 O RA ble object, at which it can be distinctly seen ; iuul let d representits ili^Umte Ironi tlie obiect-glass of tlie instriimei)!. Lei m be themagnifying power of the instrnm-nt ; tliat is, let the visual anglesutJteiKled at the eye by the object wh:n at the distance n, anu view-ed without the instrunn iit, be to the visual angle produced b theinitrunient as 1 ti m Let a be the diameter of the ,and 0 be that )• the pupil. Let the instrument be so constructed,that no pails MJu-pencils are interceptid for want ot sufticienlapcilures of the intermediate glasses. Lastly, let the light lostin refieclion or refraction be neglected. The brightness of viioii a ;?] through the instnunent will be expressed by the fraction >ii p dthj brightness of natural vision being 1. But although this fracfiinmav exceed unity, liie vision through tlie in^trun)eot will not bebrighter than natural vision. For, when this is the case, the pupildoes not receive all the light transm,l
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Keywords: ., bookcentury1800, bookdecade1800, bookidnewimperiale, bookyear1800
