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Wye Level

Catalogue number:
PH*328750

Inscriptions:
"Young & Sons, Philadelphia 5867"

Dimensions:
telescope 19 inches long

Discussion:
This instrument was made by Young & Sons, and dates from around 1875. The marking on the telescope--"Patented July 28^th 1874"--refers to the patent (#153,494) granted to J. W. Nystrom and Alfred Young, that describes a method of regulating the focus of a telescope by moving the erecting lenses back and forth while keeping the object glass and cross hairs at a fixed distance from one another.

Further Information:

Level
W. J. Young