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1900's Jacob Amsler #5 Pantograph Electrum Planimeter. It was marketed in the United States by Keuffel and Esser Company of New York.
has Jacob Amsler's signature engraved into the long tracing-arm near the tracing stylus. This planimeter was designed to quantify very large and very small areas and can handle a circle up to 38 inches in diameter! That is well beyond the range of most planimeters making this one a prize catch for any museum or collector.
The original case is lined in green velvet and is covered in leather.
The 1900 Keuffel and Esser catalog lists Amsler's #5 Pantograph Polar Planimeter under their Model Number 4256, however, on this particular instrument only the K+E branding was done with an etching on the stationary arm near the 35 gram German Silver pinned weight. There is an anomalous number etched on the long tracing arm which does not match either the K+E or Amsler's model numbering system, so maybe someone who knows more about Amsler's work could provide insights on what the number 64724 might represent.
Jacob Amsler invented the planimeter and algorithms for accurately estimating areas with unusual boundaries. He designed this planimeter to accommodate very large and very small areas as denoted in his workshop's catalog.
The pantograph feature is used for measuring very small areas opposed to tracing out the boundary of an area at a smaller scale as one would assume a pantograph would be used for. In this case the small secondary stylus is guided by the long tracer-arm for increased accuracy.
The following is cited from the Powerhouse Museum on some history of planimeters...
Production notes
At the beginning of the nineteenth century a number of inventors across Europe, Bavarian Johannes M. Hermann (1814), the Florentine Tito Gonnella (1825), and the Swiss Johannes Oppikofer (1826), worked independently on developing the planimeter to measure irregularly shaped plots of land or similar closed curves on maps. This was achieved by the rotation of a disc linked to a tracer and rolling against the side of a cone giving a measure of the area swept out by the tracer. Modifications altering the wheel and cone to a disc and wheel mechanism were made by the Swiss engineer, Caspar Wetli and the Austrian instrument-maker, Charles Starke in 1849. Then in 1855 the Scottish physicist James Clerk Maxell designed an improved instrument.
However, none of these was as simple or successful as the polar planimeter invented by the Swiss mathematician, Jacob Amsler in 1854. Amsler was born on 16 November 1823 in Stalden bei Brugg, Switzerland, the son of a farmer. He grew up in Stalden and was educated in the local schools. After graduation he studied theology firstly at the University of Jena, Germany and then at the University of Konigsberg, in the former capital of East Prussia, (from 1946 known as Kaliningrad, USSR). At Konigsberg Amsler changed his area of study to mathematics and physics inspired by his teacher Franz Neumann.
In 1848 Amsler was awarded his doctorate and then returned to Switzerland to continue his education, firstly at the observatory in Geneva then in Zurich where he qualified as a university lecturer. In 1851 he continued his research into magnetism, heat conduction and the attraction of ellipsoids while employed at a Gymnasium in the Swiss city of Schaffhausen.
In 1854 Amsler married Elsie Laffon, the daughter of a well-known Swiss scientist. Shortly after this Amsler changed his area of research and began to study the construction of precision mathematical instruments and quickly had an idea for the design of a new type of planimeter. He replaced the complex earlier arrangements of cones or rotating discs with two pivoted metal rods. The end of one rod held a tracer, while the end of the other served as a fixed pole. A measuring wheel attached to the tracer arm near the vertex recorded motion parallel to the direction of that arm. It was based on polar co-ordinates whereas earlier instruments were based on cartesian co-ordinates.
In order to make money from his invention, Amsler set up a workshop in Schaffhausen, in 1854 especially designed to produce his polar planimeter. In 1856 he published a paper 'Uber das Planimeter 'in which he gave details of his idea. By the same year his agents for the planimeter included Leebours & Secretin in Paris, Amsler & Wirz in Philadelphia, Ertel & Sohn in Munich and Elliott in London. From 1857 Amsler was devoted full time to precision toolmaking. His planimeter was small, sturdy, easy to use and popular.
Three years later he had given up all his other interests to concentrate fully on producing instruments in the workshop. By the time of his death in Schaffhausen on 3 January 1912 some 50,000 polar planimeters and 700 more complex momentum planimeters had been made in Amsler's business. Amsler went on to invent many other measuring instruments but none was as important as the polar planimeter. However, they were of sufficient qu

German 800 Silver Figural Napoleon Pastry Server; Circa 1890. The handle is the figure of Napoleon standing in a noble pose, looking left with a telescope in his left hand. He stands on a short column above the heart shaped server section with a fancy leafy garland design around the crest. Monogrammed on the back, noted as a wedding gift to Agar Adamson & Mabel Camithra. Stamped with German 800 silver hallmarks and a Fleur-de-lis makers mark (unidentified). 6.35 oz, 10.75 in. long.