Curious Sector Clinometer, Fine Wood, Artillery, Topography, 19th Century.

Direct-reading field protractor.
Its operating principle relies on a movable graduated sector driven by a pendulum system, featuring a push-button locking mechanism.
Artillery clinometer used to measure the firing angles of guns., or Surveying clinometer used to measure slopes and elevation changes.
Our instrument is quite distinctive due to its large, rectangular wooden case that fully houses the mechanism; this gives it the appearance of a carrying case, even though it is the instrument itself.
The device consists of a semi-circular brass graduated sector fully recessed into a sturdy, folding light-colored wooden case—likely boxwood or a similar species.
It is equipped with folding sighting vanes, an internal spring mechanism, and a reading window that allows for the immediate viewing of measured angle.
Its operation is as ingenious as it is efficient: the operator holds the case in one hand, sights the target while tilting the instrument, presses the release button, and then releases it once the sighting is complete. Resulting angle appears instantly in the graduated window, allowing for rapid, successive measurements.
This system is simple, robust, and remarkably modern in its design.
I disassembled for inspection: mechanism is complete, clean, and in excellent condition.
Unsigned French workmanship, with no visible marks or hallmarks; likely dates to the 1840s or 1850s.
Dimensions: 29 × 12 × 2 cm, Weight: approx. 500 g.
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eclectic — We are not professional appraisers, but we have been in the trade for over 50 years.
Hassle-free refund if not satisfied.
SIRET: FR 24 430113233. Invoice and certificate included with every shipment.