surveyor's vernier compass
Date1853-1858
Inventory Number5188
ClassificationSurveyor's Compass
Subject
Maker
H. M. Pool & Brothers
fl. 1840 - 1870
Seller
Charles C. Hutchinson
1832 - 1913
Cultural Region
Place of Origin
Dimensionsinstrument without sights: 6.5 × 16.1 × 38.4 cm (2 9/16 × 6 5/16 × 15 1/8 in.)
case: 12 × 40.8 × 19.3 cm (4 3/4 × 16 1/16 × 7 5/8 in.)
case: 12 × 40.8 × 19.3 cm (4 3/4 × 16 1/16 × 7 5/8 in.)
Material
Accessoriesbelt grip; dial cover plate; lifter arm; carrying case
DescriptionAll brass instrument with two removable sighting vanes. Both have a narrow slit with two or four circular apertures. There are two bubble levels, on one arm, positioned at a right angle and forming a "T", to level in both axes of the horizontal plane. On the other arm is an engraved graduated arc (10°-0-10°) with vernier to measure the angular variation between the magnetic and the geographic poles. (The amount of variation changes with location as does its direction east or west. Considering the graduated arc, this instrument was most likely made for New England surveying.) A thumb screw underneath the vernier moves it finely.
The silvered dial's face has eight cardinal points, with a fleur-de-lys for identifying North. Degrees are engraved on the raised scale (0-90°-0-90°), divided in degrees and marked to every ten. The instrument is supported by a ball-and-socket joint and a tripod (missing).
When not in use, the instrument is stored (with accessories, i.e. a cover plate and lifter arm with heart-shape end) in a wooden box, identified to a Boston maker and seller, Charles C. Hutchinson.
The silvered dial's face has eight cardinal points, with a fleur-de-lys for identifying North. Degrees are engraved on the raised scale (0-90°-0-90°), divided in degrees and marked to every ten. The instrument is supported by a ball-and-socket joint and a tripod (missing).
When not in use, the instrument is stored (with accessories, i.e. a cover plate and lifter arm with heart-shape end) in a wooden box, identified to a Boston maker and seller, Charles C. Hutchinson.
Signedon dial: H. M. Pool / Easton Mass
on label, inside case: Chas. C. Hutchinson / Nautical Surveying / Instruments / Charts Books / 126 Commercial St. / Boston
FunctionThe surveyor's compass is an instrument used in surveying (or in navigation in rare cases) to measure horizontal angles, what is called bearing or azimuth.
For a nice discussion of this intrument, see the following website.
For a nice discussion of this intrument, see the following website.
ProvenanceDavid Wheatland acquired from Lee Freedman, Brookline, Massachusetts, June 7, 1967. Donated to CHSI February 2, 1977.
J. Pool & Company
Date: circa 1850
Accessories: carrying case
Object number: 5200
E. & G. W. Blunt
Date: 1844-1857
Accessories: handwritten tables and charts; carrying case; ball-and-socket joint
Object number: 5187
William J. Young
Date: 1840-1855
Accessories: carrying case
Object number: 5190
Alexander Megarey
Date: circa 1840
Accessories: cover plate for compass dial; plumb bob; ball and socket tripod (2005-1-0002), carrying case
Object number: 5199
Charles Pool
Date: 1820-1835
Accessories: carrying case; ball-and-socket joint; extra needle; plumb bob; glass vial; brass plates
Object number: 5194
H. M. Pool & Brothers
Date: circa 1845
Accessories: tripod (5197b)
Object number: 5197a
William J. Young
Date: 1820-1840
Accessories: ball-and-socket joint; carrying case
Object number: 5189
Chamberlain & Ritchie
Date: 1850-1854
Accessories: carrying case; tripod (5129b)
Object number: 5129a
Samuel Thaxter & Son
Date: 1822-1831
Accessories: protective cushioned cloth; carrying case; ball-and-socket joint
Object number: 5180
See also/See also
