An alethoscope (Greek true+view) is an instrument for viewing pictures with a lens to enlarge and show them with natural relations and proportions. The alethoscope was patented by Carlo Ponti in 1861. It was used to view photographs that were colored, perforated and mounted on a curved frame. The alethoscope showed day-and-night effects whether viewing it against the light or reflect the light by two side mirrors. It is the larger version of a megalethoscope.