dumpy level
Date: circa 1850
Inventory Number: 5209
Classification: Surveyor's Level
Subject:
Maker: Adie & Son (1835 - 1880s)
Cultural Region:
Place of Origin:
Dimensions:
instrument: 17.5 × 9.2 × 30.8 cm (6 7/8 × 3 5/8 × 12 1/8 in.)
case: 11.3 × 41.8 × 11.5 cm (4 7/16 × 16 7/16 × 4 1/2 in.)
Accessories: case; dust cap and sunshade; eyepiece
DescriptionBrass dumpy level with the following major components (top to bottom): one large and one small spirit level; telescope tube; and footplate with four leveling screws.
The large spirit level, which is screwed to the top of the telescope tube, has two rectangular glass windows. Each window is printed with an unlabeled scale having ten divisions. Each scale starts some distance in from the window's inner edge.
The small spirit level is circular and is bolted to the top of the telescope tube between the large spirit level and the eyepiece.
The telescope tube has knurling around the eyepiece cap and the objective cell. Bolted to the side of the tube is the focusing screw, a large circular knob with a milled edge. Near the eyepiece are four brass screws with holes in their heads, projecting out from the tube at regular intervals. These are the screws that hold the cross hairs. The telescope as a sunshade with a knurled rim, and a swing-away dust cover on its front. The telescope itself is mounted on two brass cradles attached to the supporting horizontal platform.
Two rectangular housings project down from the platform, one at either end. Inside each are the screws for attaching the telescope cradles. The housings protect these screws from being bumped.
The platform freely rotates on a central axis set within three parallel plates. There are four large leveling screws operating between the two lower plates. The underside of the lowest plate has a large central socket with threads to match a fixture on the tripod head.
The instrument is stored in a fitted mahogany case padded in places with dark blue velvet. There are brass hooks and hinges. Also in the case is the eyepiece, 9.9 cm in length.
The large spirit level, which is screwed to the top of the telescope tube, has two rectangular glass windows. Each window is printed with an unlabeled scale having ten divisions. Each scale starts some distance in from the window's inner edge.
The small spirit level is circular and is bolted to the top of the telescope tube between the large spirit level and the eyepiece.
The telescope tube has knurling around the eyepiece cap and the objective cell. Bolted to the side of the tube is the focusing screw, a large circular knob with a milled edge. Near the eyepiece are four brass screws with holes in their heads, projecting out from the tube at regular intervals. These are the screws that hold the cross hairs. The telescope as a sunshade with a knurled rim, and a swing-away dust cover on its front. The telescope itself is mounted on two brass cradles attached to the supporting horizontal platform.
Two rectangular housings project down from the platform, one at either end. Inside each are the screws for attaching the telescope cradles. The housings protect these screws from being bumped.
The platform freely rotates on a central axis set within three parallel plates. There are four large leveling screws operating between the two lower plates. The underside of the lowest plate has a large central socket with threads to match a fixture on the tripod head.
The instrument is stored in a fitted mahogany case padded in places with dark blue velvet. There are brass hooks and hinges. Also in the case is the eyepiece, 9.9 cm in length.
Signedengraved on side of telescope tube: ADIE & SON, EDINBURGH.
on trade card inside case: ADIE & SON, / OPTICIANS, / Mathematical & Philosophical / Instrument Makers / TO THE QUEEN / No. 50 Princes Street / EDINBURGH
on trade card inside case: ADIE & SON, / OPTICIANS, / Mathematical & Philosophical / Instrument Makers / TO THE QUEEN / No. 50 Princes Street / EDINBURGH
FunctionFor use in surveying, to measure contours.
After mounting the dumpy level on a tripod at his starting location, the user levels the instrument by means of the spirit levels and the leveling screws. Then he sights a stadia rod through the telescope, moving the rod as needed until the target is centered behind the telescope's cross hairs. The difference in height between the telescope and the rod target indicates the gain in elevation over the horizontal distance between the two.
After mounting the dumpy level on a tripod at his starting location, the user levels the instrument by means of the spirit levels and the leveling screws. Then he sights a stadia rod through the telescope, moving the rod as needed until the target is centered behind the telescope's cross hairs. The difference in height between the telescope and the rod target indicates the gain in elevation over the horizontal distance between the two.
Curatorial RemarksThis object was previously numbered DW0450. ;
Case not visible in images, information from card on file ;
No new (color) images.
Case not visible in images, information from card on file ;
No new (color) images.
ProvenanceFrom S. Moskowitz, Marblehead, 4-20-72. Presented by David P. Wheatland February 1977.