Nairne Y level
Datecirca 1790
Inventory Number5228
ClassificationSurveyor's Level
Subject
Maker
Edward Nairne
1726 - 1806
Cultural Region
Place of Origin
Dimensionslevel: 13 × 50.4 × 14 cm (5 1/8 × 19 13/16 × 5 1/2 in.)
case: 14.8 × 51.7 × 17.3 cm (5 13/16 × 20 3/8 × 6 13/16 in.)
case: 14.8 × 51.7 × 17.3 cm (5 13/16 × 20 3/8 × 6 13/16 in.)
Material
Accessoriesmahogany box with clasp closure
DescriptionLacquered brass Y level with the following major components (from top to bottom): a telescope tube in two Y supports; a spirit level; and a compass.
The telescope has a knurled eypiece, and four screws around its circumference near the end cap end. The Y supports it rests in are each held closed by a brass pin shaped like a key. A brown string is tied through the hole near the end of one pin; an identical string is tied around the neck of one of the supports
A spirit level with round knobs on either end is bolted to the telescope tube. It has one oval glass window, on which three lines are etched.
A brass compass with flat needle and brass weight is incorporated into the level bar. The compass has a silvered face with an eight point "star" rose. Each cardinal and intercardinal point is labeled. The arms extending to the cardinal points are engraved with a floral pattern. Two scales are engraved around the circumference of the compass. The outermost scale is raised and has values descending from 90 to 0 (N to E), ascending from 0 to 90 (E to S), descending from 90 to 0 (S to W), then ascending from 0 to 90 (W to N). The innermost scale has values ascending from 0 to 90 (N to E), descending from 90 to 0 (E to S), ascending from 0 to 90 (S to W), and descending from 90 to 0 (W to N). The outer scale is graduated into ones; the inner scale is graduated into tens.
Two knurled knobs project out from the level bar, one horizontally (at one end) and one vertically (at the opposite end). Opposite the knob pointed down is a rectangular brass piece. A staff mount sits directly below the compass.
The Y level is missing an object glass dust slide, a focusing knob, and a tripod mount. It is stored in a mahogany box with two clasps.
The telescope has a knurled eypiece, and four screws around its circumference near the end cap end. The Y supports it rests in are each held closed by a brass pin shaped like a key. A brown string is tied through the hole near the end of one pin; an identical string is tied around the neck of one of the supports
A spirit level with round knobs on either end is bolted to the telescope tube. It has one oval glass window, on which three lines are etched.
A brass compass with flat needle and brass weight is incorporated into the level bar. The compass has a silvered face with an eight point "star" rose. Each cardinal and intercardinal point is labeled. The arms extending to the cardinal points are engraved with a floral pattern. Two scales are engraved around the circumference of the compass. The outermost scale is raised and has values descending from 90 to 0 (N to E), ascending from 0 to 90 (E to S), descending from 90 to 0 (S to W), then ascending from 0 to 90 (W to N). The innermost scale has values ascending from 0 to 90 (N to E), descending from 90 to 0 (E to S), ascending from 0 to 90 (S to W), and descending from 90 to 0 (W to N). The outer scale is graduated into ones; the inner scale is graduated into tens.
Two knurled knobs project out from the level bar, one horizontally (at one end) and one vertically (at the opposite end). Opposite the knob pointed down is a rectangular brass piece. A staff mount sits directly below the compass.
The Y level is missing an object glass dust slide, a focusing knob, and a tripod mount. It is stored in a mahogany box with two clasps.
Signedengraved on compass face: Nairne London
Curatorial RemarksImages B501071, B501072, and B501073 may be removed. They are duplicated (in a slightly better exposure) in B501486, B501487, and B501488.;
This object was previously numbered DW0801.
FunctionFor use in surveying, to measure contours.
After mounting the Y level on a tripod at his starting location, the user levels the instrument by means of the spirit level and the knobs on the level bar. 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.
The compass attached on the level bar may be used to indicate direction of measurement, or to calculate horizontal angles.
After mounting the Y level on a tripod at his starting location, the user levels the instrument by means of the spirit level and the knobs on the level bar. 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.
The compass attached on the level bar may be used to indicate direction of measurement, or to calculate horizontal angles.
ProvenanceDavid Wheatland purchased from Sotheby's, London, July 15, 1963 (lot 157), via Ernst Weil. Donated to CHSI February 1977.
Peter & John Dollond
Date: 1780-1800
Accessories: mahogany box with brass hooks, hinges, and handle; tripod (see 5240b)
Object number: 5240a
Troughton & Simms
Date: circa 1840
Accessories: mahogany box with brass handle; sun shade for telescope
Object number: 5234
Spencer, Browning & Rust
Date: circa 1800
Accessories: mahogany case with brass hooks and hinges; lens cap
Object number: 5137
Troughton & Simms
Date: circa 1840
Accessories: mahogany box with brass hinges and hooks
Object number: 5232
Buff & Berger
Date: circa 1880
Accessories: mahogany case; sunshade; screws; dust cover
Object number: 5143a
R. Iseli
Date: circa 1880
Accessories: walnut case with two adjustment tools, objective lens cap, and lens shade; Iseli trade card (inside box lid)
Object number: 5229
Buff & Berger
Date: circa 1880
Accessories: mahogany case; sunshade; screws; dust cover; tripod (5144b)
Object number: 5144a
James E. Moody
Date: circa 1880
Accessories: mahogany case; sunshade; dust cap; tripod (5141b)
Object number: 5141a
John H. Temple
Date: circa 1870
Accessories: mahogany case; sunshade; tripod (5142b)
Object number: 5142a
W. & L. E. Gurley
Date: before 1882
Accessories: mahogany case; leather belt; six metal screws; tripod, see 5148
Object number: 5148
Iszard-Warren Co., Inc.
Date: circa 1910
Accessories: mahogany case with brass corners and lock; key missing; leather strap; screwdriver; dust cover; sunshade; tripod, see 5150b
Object number: 5150a
See also/See also
