This site is an early draft created to share digitized megalethoscope slides as quickly as possible. Once the full collection is online, the design and presentation of the website will be refined.
The Megalethoscope (also known as the Megalitoscopio and also spelled Megaletoscope) was invented around 1870 by Carlo Ponti. Each slide offered both a daytime and nighttime view: with the viewer’s doors open, mirrors reflect light onto the front of the slide, and when the doors are closed the light travels through the layers to create a breathtaking transformation.
We believe this collection was purchased in Venice by my great-great-grandfather’s brother, John Riordon, shortly before his death in 1884. Because the megalethoscope viewer and its slides could only be obtained directly from the creator, Carlo Ponti, it’s likely that John acquired them from Ponti himself. The slides were photographed without using the original viewer, which measures roughly 34" long, 20" wide, and 24" tall. Each slide is 16" × 12" and built from four layers: the photograph, a protective canvas backing, a color layer, and an opacity layer. Learn more about Carlo Ponti and his Megalethoscope.
Below, you can view each slide using an online viewer created with Knight Lab Juxtapose. We hope you enjoy exploring these images as much as we do. Please check back often—many more slides remain to be digitized and posted.