Borda type repeating circle with case.

Repeating circle (Borda circle) made by Etienne Lenoir, Paris, France, about 1780. Circular polished brass frame, limb and fittings, a wooden handle. Signed on one of the struts: Lenoir AParis no. 53. Brass scale from 0° to 720° every 20'. Two brass verniers to 1', zeros at the right. The index arm carries the index glass; the telescope arm carries the horizon glass. The tangent screw is on the front of the index arm; the clamping screw is on the back. A second tangent screw and clamping screw are on the back of the telescope arm, at the objective end. Three detached index shades (all red); two detached horizon shades (red and green), all the shades are secured by thumb screws. Magnifier on a 60 mm swivelling arm. Index- and horizon-glass adjustment by square-headed screws and a detached key. Two bubble levels are fixed at a right angle on the front of the telescope arm. Telescope (170 mm), inverted image, two parallel cross-wires, is fixed on two telescope brackets, with perpendicular adjustment on both by rising-pieces and milled knobs. A round plane mirror (probably not original to this instrument), a diaphragm, an adjusting key, and a screwdriver. A square, fitted oak box with the remains of a leather carrying handle.

Details

Category:
Astronomy
Object Number:
1910-128
type:
repeating circle and instrument case
credit:
J.C. Stevens Auction House

Parts

Case for Borda type repeating circle.

Case for Borda type repeating circle.

Case for Borda reflecting circle by Lenoir in fitted box, circle 11", outside, graduated circle 27 cms, complete with telescope, glasses 2 levels and handle adapted for stand graduated 0[o] -720[o] on brass into 1/3[o] by vernier to 1' two verniers, one with microscope screw handle and screw driver, round plane mirror (?) 3 index glasses (red) 2 horizon glasses ( green, red) 1 diaphragm

Measurements:
overall: 75 x 330 x 310 mm
Materials:
oak
Object Number:
1910-128 Pt1
type:
instrument case
Image ©
The Board of Trustees of the Science Museum
Borda type repeating circle.

Borda type repeating circle.

Borda reflecting circle by Lenoir circle 11", outside, graduated circle 27 cms, complete with telescope, glasses 2 levels and handle adapted for stand graduated 0[o] -720[o] on brass into 1/3[o] by vernier to 1' two verniers, one with microscope screw handle and screw driver, round plane mirror (?) 3 index glasses (red) 2 horizon glasses ( green, red) 1 diaphragm

Object Number:
1910-128 Pt2
type:
reflecting circle (borda)