United Kingdom - Scientific compass - 1800-1850

Antique Georgian Brass Pantograph by John Bleuler, London (c. 1790–1820).

An antique precision instrument that joins the worlds of art and engineering, an exquisite pantograph by the esteemed London instrument maker, John Bleuler. A masterpiece of Georgian-era scientific craftsmanship, this instrument was designed for the meticulous enlargement and reduction of maps, architectural drawings, and fine art.

The set is remarkably well-preserved, featuring precision-machined brass arms and a deep-patinated mahogany case. Of particular note is the original handwritten copperplate instruction sheet affixed to the interior of the lid—a rare survivor that provides a window into the professional drafting practices of the early 19th century. This is not merely a tool, but a piece of history, perfect for the serious collector or museum collection of antique scientific instruments.

John Bleuler (1757–1829) was a Swiss-born instrument maker who established his business in London, operating primarily from the late 18th century until his death. Given his operational period and the style of the mahogany case and the handwritten copperplate instructions, this pantograph dates to the late 18th to early 19th century (c. 1790–1820).

This brass pantograph is a mechanical linkage system used to copy, enlarge, or reduce drawings, maps, and diagrams with high mathematical precision, it works on the principle of a parallelogram linkage, allowing a tracer (a stylus) to follow an original image while a pencil reproduces it at a different scale. The specific accessories shown here each serve a vital mechanical purpose in this process. The Heavy Circular Weight serves as the fixed fulcrum for the entire instrument. The pantograph pivots around this point, which is anchored to the drawing table, ensuring the linkage remains stable while you trace your figure. The brass cup with lead weight acts as a housing for either the pencil or the tracer stylus. It is weighted to ensure consistent pressure is applied to the paper, allowing for a steady line.
The Tracer (Stylus) was used by the operator to trace the contours of the original drawing or map.

The instruction sheet provides the logic for reconfiguring the arms to change the scale:

To Reduce a Drawing: Set the fulcrum as the weight, place the pencil at point D, and use the tracer at point C.

To Enlarge a Drawing: Set the fulcrum as the weight, place the tracer at point C, and the pencil at point D.

To Copy at the Same Size: Fix the sliding sockets at marks designated as 1/2.

By moving the sliding sockets along the graduated brass arms to different numeric proportions (such as 2/3, 3/4, or 1/12), the user can mathematically control exactly how much the drawing is enlarged or reduced.

The case measures 53.5 x 28.5/10.5 x 12.5cm (21" x 11.22/4.13" x 4.92").

The period image is included for context but has been AI generated so please rely on the quoted size for accurate dimensions.