Accession No
3677
Brief Description
circumferentor, Pearson.Henry S, 1830-1860 (c)
Origin
Portland
Maker
Pearson. Henry S.
Class
surveying
Earliest Date
1830
Latest Date
1860
Inscription Date
Material
metal; wood
Dimensions
length 375mm; breadth 156mm; height 168mm
Special Collection
Provenance
Purchased from Tesseract, Hastings-on-Hudson, New York, USA; Lot 19, no. 42, 1987.
Inscription
‘H.S. PEARSON. PORTLAND’ (around centre of compass dial)
Description Notes
A form of surveying compass, where fixed sights are mounted either side of a compass box in which a magnetic needle is pivoted above a scale of degrees. Early American instrument made of dark stained wood.
Condition: fair; complete.
References
Events
Description
The circumferentor is an instrument that derives from the reverse side of an astrolabe. It is used to measure horizontal angles, or vertical angles by suspending the instrument from its shackle.
The circumferentor was described by Arthur Hopton in 1611, though passing references had been made to it in earlier works. It became one of the standard pieces of equipment of the surveyor throughout the 17th and 18th centuries.
31/08/2006
Created by: updated by Ruth Horry on 31/08/2006
FM:43497
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