variation compass
Date: circa 1780
Inventory Number: 5127
Classification: Variation Compass
Subject:
Maker: Georg F. Brander (1713 - 1783)
User: Societas Meteorologica Palatina (1780 - 1795)
User: Samuel Williams (1743 - 1817)
User: Edward Wigglesworth (1732 - 1794)
User: Isaac Rand (1743 - 1822)
User: Department of Physics, Harvard University (founded 1884)
Cultural Region:
Place of Origin:
Dimensions:
34.4 × 21.3 × 8.2 cm (13 9/16 × 8 3/8 × 3 1/4 in.)
DescriptionMarble base with molded edges in the middle of which a rectangular compass box is mounted. In upper and lower left corners of the base there are two brass sights. "ORIENS" engraved along left edge, "OCCIDENS" along right. At the bottom a curved scale graduated by degrees from 35 to 0 to 34 and numbered by fives from 30 to 0 to 30. 0 about 1/16" off-center. Below scale, "ab. Occid. ad Orient." inscribed to left of 0. "ab. Oriend ad Occid." to right of 0.
Box compass 1 1/8" high of blackened wood with glass cover and brass base. Base
extends below box under mirror (1.25" by 1") encased in engraved brass frame and mounted facing box at about 45 degree angle, leaning away from box. Base extends into a vernier divided into 20 unequal sections. Lettering on vernier reads from top (closest to mirror) to bottom (closest to scale):
"Trina Minuta 30 ab 45 Occid. (symbol) ad 15 Orient. 30; 30 ab 15 Orient 60 ad
45 Occid. 30"
Brass base forms bottom of compass box, in centre of which is mounted a nededle with quartz bearing; base of needle munting encircled with detachable engraved brass oval.
Entire compass box and vernier base attached to stone only by screw under
compass needle, and revolve around that point.
Box compass 1 1/8" high of blackened wood with glass cover and brass base. Base
extends below box under mirror (1.25" by 1") encased in engraved brass frame and mounted facing box at about 45 degree angle, leaning away from box. Base extends into a vernier divided into 20 unequal sections. Lettering on vernier reads from top (closest to mirror) to bottom (closest to scale):
"Trina Minuta 30 ab 45 Occid. (symbol) ad 15 Orient. 30; 30 ab 15 Orient 60 ad
45 Occid. 30"
Brass base forms bottom of compass box, in centre of which is mounted a nededle with quartz bearing; base of needle munting encircled with detachable engraved brass oval.
Entire compass box and vernier base attached to stone only by screw under
compass needle, and revolve around that point.
Signedengraved on box above needle: G. F. / Brander / fecit / Aug. Vind.
Inscribedtwo stamps on base, one smeared and illegible, other says: 8-28
FunctionUsed to measure magnetic variation, the angle difference between the geographic and the magnetic north.
The base is oriented towards the astronomical south (merides) using sights on the side, and the compass box is rotated to be parallel to the needle with the help of the mirror underneath . The magnetic declination can the be read from the scale and vernier.
The base is oriented towards the astronomical south (merides) using sights on the side, and the compass box is rotated to be parallel to the needle with the help of the mirror underneath . The magnetic declination can the be read from the scale and vernier.
Historical AttributesThis variation compass was part of a set of instruments provided by the Societas Meteorologica Palatina in 1780 to observers in a total of 37 cities stretching from the Urals, through Europe, to Greenland and America. In addition to a variation compass, a thermometer, a barometer and a hyrometer were sent after calibration in Mannheim; the cost of the instruments and their transport was paid by the Society.
In North America, the corresponding member of the Society was Samuel Williams at Harvard, with the help of Edward Wigglesworth and Isaac Rand. Their observations were sent back to Mannheim and became part of the annual publication Ephemerides.
In addition to observations for the Meteorological Society,this variation compass (plus the one made by Edward Nairne -CHSI 0025-, and one by Gordon Knight)was used as part of the initiative started by the American Academy of Arts and Sciences to follow the daily changes in magnetic variation. Williams went on to collect data on variation in Massachusetts, Vermont, New Hampshire, Maine, Rhode Island and New York through the 1780s-90s.
The stamps with numbers on the instrument indicate that much later, in the last decades of the 19th century and first decades of the 20th, the instrument continued to be used by the Harvard Physics Department.
In North America, the corresponding member of the Society was Samuel Williams at Harvard, with the help of Edward Wigglesworth and Isaac Rand. Their observations were sent back to Mannheim and became part of the annual publication Ephemerides.
In addition to observations for the Meteorological Society,this variation compass (plus the one made by Edward Nairne -CHSI 0025-, and one by Gordon Knight)was used as part of the initiative started by the American Academy of Arts and Sciences to follow the daily changes in magnetic variation. Williams went on to collect data on variation in Massachusetts, Vermont, New Hampshire, Maine, Rhode Island and New York through the 1780s-90s.
The stamps with numbers on the instrument indicate that much later, in the last decades of the 19th century and first decades of the 20th, the instrument continued to be used by the Harvard Physics Department.
Curatorial RemarksThis instrument is almost identical to the declination compass at the Institut Royal Meterologique, Brussels. That one has the same origin and is even marked on the marble "Carolus Theodorus / Elector Palatinus / anno 1780". The one in Brussels has a more ornamented box lid and has the marble base on a wooden frame. See Published References.
ProvenanceStamps typical with instrument coming from the Physics Department, Harvard University.
Permanent loan from the Elector Patinate, from the Collection of the Manheim Observatory 1785, p.121 (noted on Harvard College Records).
Permanent loan from the Elector Patinate, from the Collection of the Manheim Observatory 1785, p.121 (noted on Harvard College Records).
Published ReferencesThe gift by the Societas Meteorologica Palatina and observations made by Samuel Williams are described in: Brooke Hindle, The Pursuit of Science in Revolutionary America (University of North Carolina Press, 1956), pp. 348-349.
The almost identical instrument in Brussels has a photograph and description in: Henri Michel, Scientific Instruments in Art and History (N.Y., 1967), plate 101, pages 199-200.