Gerlach protractor

The presented protractor is a device for measuring angles in relation to geographic directions when working in the field. Due to its design and function it is a device in between a steel square (which only allows plotting of 45° and 90° angles) and a classic optical theodolite (allowing any angles to be measured). Instead of a scope, the device has two vertical sights, enabling readout of the angle between the observed object and a given direction thanks to a compass in the bottom part. The instrument presented was made around 1900 in the Specjalna Fabryka Instrumentów Geodezyjnych i Rysunkowych Gustawa Gerlacha in Warsaw. The establishment operated from 1816 until World War II and it specialised in the production of surveying instruments. Manufacturer: Specjalna Fabryka Instrumentów Geodezyjnych i Rysunkowych G. Gerlach, turn of 19th/20th c. Inv. No.: MIM905/XI-46 Model prepared on the basis of photogrammetric measurements. Licence: CC BY-NC-SA