From Thomas Jefferson Encyclopedia
Created: late 18th century
Origin/Purchase: United States and England
Materials: mahogany, glass
Dimensions: 65.1 x 26.7 x (25 5/8 x 10 1/2 in.); D (base): 21.7 (8 9/16 in.)
Accession Number: 1942-16
Historical Notes: The perspective glass, or vue d'optique, is an instrument for observing engraved prints or maps. The combination of magnifying lens and angled mirror provided enlarged views of heightened perspective of prints placed on a table below. Because the mirror reversed the image, engravers of the period produced prints in reverse particularly destined for use with perspective glasses or their public form, traveling peep shows.
No certain documentary reference to a vie d'optique, also known as a "zograscope" or an "optical diagonal machine," has been found in Jefferson's records, nor have any reversed image prints survived among the collections of his descendants. His Memorandum Book does note a 1769 payment to James Craig in Williamsburg for the repair of a "perspect. glass." This could represent a vue d'optique, but might also be a simple spyglass.