Images(18)

Troughton & Simms Y level

Datecirca 1840

Inventory Number5234

ClassificationSurveyor's Level

Subject

Maker Troughton & Simms 1826 - 1923

Cultural Region

Place of Origin

Dimensionslevel: 23 × 14 × 45.2 cm (9 1/16 × 5 1/2 × 17 13/16 in.)
case: 18.2 × 51.8 × 28 cm (7 3/16 × 20 3/8 × 11 in.)

Material

Accessoriesmahogany box with brass handle; sun shade for telescope

DescriptionBrass Y level consisting of the following major components (from top to bottom): a telescope tube in two Y supports; a compass; and a foot plate with four leveling screws.

Two fitted bronze rings around the telescope tube protect its points of contact with the Y supports. Bolted to the top of the tube at its center is a single knob with two knurled rings around its edge. The eyepiece end of the telescope tube is significantly narrower than the opposite end. On the eyepiece of the telescope is a sliding dust plate.

The telescope tube's Y supports are each held closed by a brass pin having a brass loop at one end. Each loop is tied with a string to the neck of the respective Y support. Projecting down from one support is a knob for fine leveling, with two knurled rings around its edge.

Incorporated into the level bar is a compass having a plain silvered face and silvered edge-bar needle. Each of the cardinal and intercardinal points are marked, with long lines extending from the center to each of the former, and shorter lines extending from an off-center bolt to each of the latter. Two scales are engraved on the compass's face. The outermost, raised scale has values ascending from 0 to 360 (clockwise), graduated into ones. 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 latter scale is graduated into ones. There is a brass knurled knob on the brass surrounding the compass face, near the mark for SE.

The portion of the vertical spindle directly below the compass is finished in black. attached to this are two boxes, also black. A single knob projects horizontally from each of the boxes. One knob is circular, with two knurled rings around its edges; the other is key-shaped.

Four leveling screws with circular knobs having two knurled rings around their edge are sandwiched between the circular foot plate and a brass disc.

The instrument is stored in a mahogany case with brass hinges and handle. The case also contains a brass sun shade. Pasted inside its lid is a trade card with Cyrillic lettering.

The instrument is missing its spirit level.

Signedengraved on compass face: Troughton & Simms / LONDON ; printed on card pasted to inside of case: [in old Russian] [company name] / [PHYSICISTS-MECHANICS & OPTICISTS] / [address in St. Petersburg]

Inscribedstamped on top of brass footplate: 13; stamped multiple times on mahogany case: 13

Curatorial RemarksImages B401464, ... , B501470 may be removed. They are duplicated (in slightly better exposure) in images B501479, ... , B501485.; This object was formerly numbered DW0931.; The trade card pasted on the inside lid of the box indicates that this item was likely sold in Russia.

FunctionFor use in surveying, to measure contours.

After placing the Y level, on a tripod, at his starting location, the user levels the instrument by means of a spirit level (missing), the four leveling screws, and the Y-support knob. 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 Roux-Devillas Paris, June 1, 1963 (lot 1/2). Donated to CHSI February 1977.