Polar planimeter
Maker
J Halden and Company
Date19th century
Object number00038294
NameSurveying instrument
MediumSteel, plastic
DimensionsOverall: 255 mm, 0.16 kg
ClassificationsTools and equipment
Credit LineANMM Collection Gift from Des Kerns
DescriptionA planimeter is a type of mechanical analog computer which integrates or calculates an area and records that area on a drum and disk as a tracing point moves over the boundary of the figure to be measured. They were used in engineering, naval and marine architecture until the mid-1980s.HistoryPlanimeters were instruments used in the evaluation of plane areas of any shape from blueprints, maps, photographs, drawings, recorder diagrams, x-rays, etc. They were traditionally used by steam engineers, railway and naval architects and are still used today for different applications including cartography, hydrology, quantity surveying, road, dam and railway construction, ship design, mold patterning, mathematics, biology and medicine.
The planimeter was the first instrument used for measuring area by continuous integration or calculation, invented by the German engineer, J M Hermann, in 1814. The first complete planimeter was invented by Johannes Oppikofer and exhibited by him in Paris in 1836. A patent on a planimeter was granted in 1849 to Kasper Wettli and George Starke. The Swiss scientist Jacob Amsler invented the modern polar planimeter in 1854 which proved to be cheap, accurate and robust.
In order to make money from his invention Amsler-Laffon set up a workshop in Schaffhausen in 1854 specially designed to produce the polar planimeter. The shop produced over 50,000 instruments between 1854 and 1912. (O'Connor and Robertson, 2000). Amsler-Laffon was awarded medals at the world exhibition in Vienna in 1873, Paris in 1881 and he was elected to the Paris Académie des Sciences in 1892.
The Halden planimeter is a marvel of mechanical skill and mathematical calculating accuracy. Made from German silver and steel it has an option to alter the radius of the tracing arm from 0 to 10. The results are read directly with the aid of a vernier.
J Halden & Co was established in 1877 in Rowsley Works, Reddish, Manchester. The manufacturing company was famous for its Halden Calculus Circular Slide Rule and various measuring, drawing and surveying instruments. The company became J Halden and Co Ltd in 1930 with an office in London.SignificancePolar planimeters were essential mathematical calculators and accumulators for the marine and naval engineer. The use of the planimeter saved time and money in the calculation of linear and plane space and in the calculation of volume for irregular shaped structures. They were superceded by Computer Assisted Drawing and calculation programs in the mid 1980s.
