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Other Ramsden Instruments


Ramsden Dual-Power Monocular

Signature Ramsden, London

Date Circa 1770
Dimensions English Metric
Main Tube Length 1.7in 44mm
Main Tube Diameter 1.1in 27mm
Total Length 3.2in 80mm
Closed Length 2.4in 60mm
Objective Clear Aperture Diameter 0.9in 23mm


This monocular has a short round parallel silver-plated brass barrel. The objective lens is an achromatic doublet, mounted in a brass cell. It may not be original. It has one brass draw (without retention), two eye lenses, and a flared eyecup. The eye lenses are used one at a time by sliding a pin on the face of the eyecup to either position "1" or "2." These two lenses are mounted in a small metal plate inside the eyecup and pivot from one position to the other. There are two lines scribed around the draw also numbered "1" and "2." The eye lens and draw set at position "1" gives about 3X magnification and at position "2" about 6X magnification. When the sliding pin on the eyecup is set between "1" and "2" the eye lenses are covered. It is signed "Ramsden London" on the face of the eyecup. It comes with a case, covered with red leather.


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