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History of Science Museum

Variation Indicator for Navigator's Parallel Rule, English, 19th Century

Inventory Number 52743


Acknowledgement: © History of Science Museum, University of Oxford, inv.52743

Item type
Object
Primary inscriptions
Unsigned
Physical material
Brass
Object type
Rule
Dimensions
Height: 83mm Width: 83mm Depth: 47mm
Inventory No
52743

Description

See 37414 for another example, with complete instrument.

Square base plate with bevelled edges divided to 8 ungraduated equal parts and with divided circle of 4 quadrants, with cardinal points labelled. Mounted 7mm above base on a central shaft is a circular disc with a divided compass rose subdivided to 128. The disc can be fixed at any orientation by a knurled knob.