Surveyor's Vernier Compass
date: label: date made
content: 1818
name: label: maker
content: Whitney, Thomas
notes: label: Description
content: In the <i>Aurora General Advertiser</i> for Feb. 23, 1808, Thomas Whitney stated that he made surveyor's compasses "of the most accurate construction, and with several late improvements, which have been approved of, in preference to any other, by several eminent surveyors, and others." What these improvements were, however, he did not say. In <i>Whitely's Philadelphia Annual Advertiser</i> for 1820, Whitney announced that during the past 13 years or so he had made about 500 compasses, "the good qualities of which are well known to many Surveyors, in at least sixteen of the States and Territories of the Union." Another Whitney document, this one dated March 1, 1814 and headed "Variation of the Compass," provides information about the extent of the variation in several states as observed by different surveyors, and the change of variation with time. It also describes five ways to determine a meridian line, so that the local variation can be found.
label: Description
content: This compass, marked "Thos Whitney maker Philadelphia No 437," has a variation arc on the north arm that extends 25 degrees either way. The vernier is moved by rack and pinion, and reads to 5 minutes. A level vial is on the south arm. Under the socket on the bottom of the compass is the date "1818."
label: Description
content: The cover of the box is marked in ink "R. R. MORRIS NEW YORK, May 27th 1817 red'd from Philadelphia." Two printed cards are inside the box. One, signed by Whitney and dated March 1, 1817, is headed "Care in the Use of the Compass." The other is a trade card that indicates that while Whitney specialized in compasses, he made many other instruments as well. The date of the card can be inferred from the statement that Whitney "has made near 400 Surveying Compasses."
label: Location
content: Currently not on view
place: label: place made
content: United States: Pennsylvania, Philadelphia
setName: label: See more items in
content: Medicine and Science: Physical Sciences
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content: Surveying and Geodesy
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content: Measuring & Mapping
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.328751
label: accession number
content: 308252
label: catalog number
content: 328751
objectType: label: Object Name
content: Surveyor's Compass
label: Object Name
content: surveyor's compass
physicalDescription: label: Measurements
content: overall length: 14 in; 35.56 cm
label: Measurements
content: needle: 5 1/4 in; 13.335 cm
label: Measurements
content: overall in box: 4 in x 14 1/2 in x 7 1/2 in; 10.16 cm x 36.83 cm x 19.05 cm