A planimeter is an instrument for determining the surface area of flat surfaces, e.g. an area on a map. Measurement of the area of geometric shapes is possible in many ways, which results in there being several types of planimeters, which use different principles of operation and are built in different ways. The first planimeter was designed in 1814 by Johann Martin Hermann, after which a rapid development of different designs of these devices followed. The planimeter presented here is relatively simple. It has the form of a frame equipped with parallel threads placed at small distances from each other. After applying on a drawing or map, the frame allowed measuring a surface by breaking it up into a series of stripes, whose total length defines the surface area of the shape. The presented instrument was made about 120 years ago in the Viennese establishment of Joseph and Carl Neuhöfer, specialising in the production of different types of land surveying instruments. The high precision of execution of the brass frame with markings and scales is noteworthy. This unit was used until the 1960s by a land surveyor in Kraków, to make land register maps.

References:
F. Kucharzewski, Planimetry polskie i ich wynalazcy, “Przegląd Techniczny” 1902, https://bcpw.bg.pw.edu.pl/Content/4521/przeglad_techniczny_1902_t40_nr21_s247.pdf, accessed: 2.06.2021.
M. Kluza, Polscy wytwórcy instrumentów naukowych w XIX wieku [w:] Polscy twórcy aparatury naukowej, ed. A. Strzałkowski, Monografie series, vol. X, Kraków 2006, pp. 277–285.
C. Neuhöfer, Neuhöfer & Sohn of Vienna, translated by J. B. te Pas, „Bulletin of the Scientific Instrument Society” 1997, issue 52 (1997), pp. 31-32, https://cdn.website-start.de/proxy/apps/ilai8i/uploads/gleichzwei/instances/83BA095F-F52A-41E5-A000-752EC15ABDB0/wcinstances/epaper/f390f418-fd31-482d-b173-cde29019c6ce/pdf/Neuh%C3%B6fer-&-Sohn.pdf, accessed 01.06.2021.