Keufell & Esser Stadia N-4100

The Stadia 4100 was produced from 1895 until 1959. Fabricated with mahoganny covered with celuloid, this Mannheim style rule was designed for the surveying work. During the 64 years this rule was fabricated, different versions version were produced. The first Stadia rule produced in 1895 was a 20 inches inches no cursor model, with only four scales in the front face, a cost of $13.50 USD (around $495 USD in 2022), and it was designed to solve the equations involved in stadia measurements:

Stadia is a method of surveying in which distances and elevations (heights) are obtained by observing the interval on a graduated, upright rod (stadia rod) intercepted by two parallel horizontal lines (stadia hairs or stadia wires) in a surveyor’s transit set up at a distance from the rod. Also, the graduated rod used to measure the distance from the observation point to the place where the rod is positioned, is known as Stadia.

The first 10 inches model was released until 1901, with a cost of $ 4.50 USD ($165 USD in 2022). The first model with all metal framed cursor appeared in 1913, (also $ 4.50); the model with all glass cursor appeared in 1915 ($4.50), and the model with metal rimmed cursor was released in 1936, with a cost of $6.50 (Around $238 USD in 2022).

The original scale set on the 1895 original model are: Front R [H V] A, Back slide B. The models produced from 1906 to 1927 added an aditional scale on the slide, so the scale set for is Front: R [H HC V] A, Back slide: [B ]. The model produced after 1927 added an additional reverse scale on the back slide as well as an inches and a cm scales on the edges of the rule, Front Scale: 10in // R [ H, HC, V ] A || 25cm, Back Slide: [ C, B ] and Back of the rule: Instructions for horizontal distance and elevation calculations.

According witht he serial number engraved and the correlation done by Ed Chamberlain, the model in this collection was fabricated around 1941.

Click on the next link to see professional panoramic pictures of the 4100 model

References:

  • Cyphers, Mike: 9.10 Stadia Rules. Following the Rules — A Slide Rule Collection. http://followingtherules.info/stadia-rules.html

  • O.E. van Poelje: Stadia or Tachymetrical Slide Rules. UKSRC Gazette Nr. 6 August 2005. http://followingtherules.info/stadia-rules.html