7-inch mirror blank
Date: 1880-1920
Inventory Number: 1998-1-0514c
Classification: Mirror
Dimensions:18 × 18 × 1.8 cm (7 1/16 × 7 1/16 × 11/16 in.)
Description1998-1-0514 is a mixed collection of glass lenses. They have been separated and tagged as 1998-10-0514a-d.
1998-1-0514a
Crown glass plano-convex lens with a nibbled edge. The glass is greenish. The diameter is 6.5 inches (16.4 cm) and the focal length is 9.5 feet. F/1.46
1998-1-0514b
This lens is very thick and may be bi-concave. The curves are very shallow. It is likely the flint element of a telescope objective. The aperture is 6 inches. It still has red rouge around the edge.
David Wheatland penciled the following on a piece of cardboard with the lens:
from / Milton + Esther /
marked: PROPERTY OF / RICHARD CROWELL/
from Byerly 10/13/64 DW /
Long focus mirror---
1998-1-0514c
This is a thick disk of greenish unpolished glass. It appears to be a blank for a 7-inch mirror. The diameter 7.1 inches (18 cm) and the thickness is 1.7 cm.
1998-1-0514d
This is a greenish glass mirror with very shallow concave curvature. The diameter is 8.5 inches (21.6 cm). There is a small hole about 1.5 inches from the rim.