Identifier: younggentlemanla02mart (find matches)
Title: The young gentleman and lady's philosophy : in a continued survey of the works of nature and art by way of dialogue
Year: 1759 (1750s)
Authors: Martin, Benjamin, 1704-1782
Subjects: Science
Publisher: London : Printed and sold by W. Owen and by the author
Contributing Library: University of Pittsburgh Library System
Digitizing Sponsor: University of Pittsburgh Library System

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ance, may be encreafed with fufficient Degrees ofBrightnefs and Diftinanefs of Vifion. Thus, for ExperimentSake, I will take that Glafs from the Window-ftiut, and placeanother in its Room of double its focal Diftance, vi-z. 72.In-ches ; then remove the Screen to the fame Diftance from theWindow, where now you fee the Landfcape greatly enlarged,twice as much in Length and Breadth, and therefore 4 Timesas large in Surface as before ; and as the Diameter of the A-perture of this Objca-glafs is twice as much as that of theformer, there will be fame Quantity of Light in the Piaure ; fo that each Image is now equally bright as before : Then I apply a Glafs of 3 Inch focal Diftance behind, which will fliewthe Objea under the fame Angle as before, the Hole in the Screen being now twice as large. Go, and apply your Eye to the Tube, my Euphrofync, and tell me how it appears. Euphrof. I will. By what you have faid, Things ought to appear nearly the fame as before. — But the Scene appears every
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and Ladys Philosophy. 217 every Way more grand ; and I cannot help thinking that the-Objecls feverally appear not only more perfecPc, but alio larger atthe fame Time. Cleoii. Your Obfervations are very juft, except the laft ; theObjects are not in Reality magnified : This is a Deception otthe Fancy ; for we aWays imagine that the more illuflrious any Thino- appears, the larger it muft be at the fame Time. « That the View of every Part is more perfect, I v-^i)! allow ; forwhich Reafon I fliall (hew ydu, \)^) another Experiment, thatthe magnifying Power of the Eye-glafs may be increafed, bychanging that which is a new One of 3 Indies focal Diftance, and fubflituting another in its Stead of 2 Inches only . This is done : Take a View as before, Euphrof. I do ; and cannot but fay, the Obje6ls appeal fuf-ficiently diftinil:, though magnified much more than before : • But they appear not altogether fo lightfome, or bright. Cleon. They are magnified novi in Proportion as 2 to 72, orI 1036;

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