These were manufactured by J.C. Freeman & Company, Opticians of Worcester, Mass. They measure about 3" X 5" with cut-out slits through which to view the sun during an eclipse. Also included are rectangular films in small envelopes.
“Eclipse-O-Scopes to View the Sun,” Mount Desert Island Historical Society, accessed April 3, 2025, https://mdihs.digitalarchive.us/items/show/2566.Item 2932
