Two smaller mounted prisms. By Duboscq, Paris See a <link ref="tec3104">figure</link> of the same prism on another photograph from the Harvard Collection. See a <link href=" http://www.sil.si.edu/digitalcollections/trade-literature/scientific-instruments/files/51748/imagepages/image58.htm">figure</link> in a catalog by Duboscq, 1885. See a color photograph of this device in the <link href='http://dssmhi1.fas.harvard.edu/emuseumdev/code/emuseum.asp?rawsearch=Number%2F%2C%2Fis%2F%2C%2FWJ0037%2F%2C%2F0%2F%2C%2F0'>Harvard Collection of Historical Scientific Instruments</link>. See another color <link href='http://physics.kenyon.edu/EarlyApparatus/Optics/Prisms/Prisms.html'>photograph</link> of a similar prism from Thomas B. Greenslade's collection "Instruments for Natural Philosophy." Two smaller mounted prisms. By Duboscq, Paris

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