The megalethoscope is an optical apparatus, a sophisticated version of the peep show, designed by Carlo Ponti of Venice before 1862. Invention The megalethoscope is a larger version (mega-) of the alethoscope, (from the Greek “true”, “exact” and “vision”) of 1860 which Ponti presented to the Société française de photographie in 1861, then in April, to the Istituto di Scienze, Lettere ed Arti in Venice, earning an honourable mention there in May. He obtained a patent in January 1862 and commenced marketing it and photographs to be viewed using the device. His invention was awarded Grand Prix at the International Exhibition in London in 1862. The megalethoscope was produced for him by cabinetmaker Demetrio Puppolin, whose name is inscribed on different models. It was a substantial status symbol, an often elaborate item of furniture that only the well-to-do could afford; some are highly decorated with pearl inlay and marquetry, and they often held collections of photographs in a cabinet beneath. Description, operation and effect The megalethoscope, like the similar graphoscope which descends from the eighteenth century zograscope predating photography, was and is often confused with the stereoscope which was of a different design and effect. The megalethoscope was for the viewing of single, usually 25 x 34 cm., albumen prints which Ponti also produced and published, mostly for the tourist market in the waning era of the Grand Tour, but also for connoisseurs of art and architecture, in large quantities and to an international clientele through outlets in Europe, England and America. The megalethoscope and the alethoscope are capable of a certain illusion of relief. Both devices enlarged photographic views through a wide, thick magnifying glass, or compound lens, that creates an illusion of the subjects' plasticity, perspective depth and modelling. The instrument’s arrangement minimises surrounding indicators of depth that would let us know this is a flat picture, and also because the image is magnified to nearer the scale of the real scene the picture is depicting. As the light coming from the lens to the eyes is collimated, it confounds accommodation; the image is suspended at an indeterminable range. The broad, thick lens could also enhance depth perception by creating binocular stereopsis, because each eye views the image through a different part of the magnifying glass; chromatic aberrations at he edges of the lens may contribute to chromostereopsis; and depth clues in the image, which were usually in