Brunsviga 13Z-18 Mechanical Calculator, ca. 1937
Serial number 202758
The firm Grimme, Natalis & Co (GNC) was established in 1871 to build sewing machines and domestic appliances at Braunschweig (Brunswick) in Germany. In 1892 engineer Franz Trinks was instrumental in securing the German manufacturing rights for the Odhner pinwheel calculators. The first machines were built according to W.T. Odhner's 1890 design, and were distributed under the brand name "Brunsviga".
Trinks continued to develop and refine the Brunsviga calculator over a period of almost 30 years. Between 1905 and his retirement in 1925 he received over 40 US patents, and was awarded an Honorary Doctorate by the Braunschweig university. The "new Brunsviga" range appeared in 1925, and the "13-series" in 1927. The range continued to expand with a portable stepped-drum machine in 1932, and a full-keyboard adding and listing machine in 1936. Production resumed after the 1939-45 war with a new range of 13-series machines, a motorised version of the stepped-drum machine, and a range of small adding machines.
Grimme, Natalis & Co was originally established as a "Commanditgesellschaft auf Aktien" ("C.a.A." on the logo, meaning an association with shares). On its fiftieth anniversary in 1921 it became Grimme, Natalis & Co AG (Aktiengesellschaft, or corporation). In 1927 the name was changed to "Brunsviga Maschinenwerke Grimme, Natalis & Co AG", and later to just "Brunsviga Maschinenwerke AG" (Brunsviga Machine Works). In 1957 Brunsviga entered into an agreement with Olympia Werke AG of Wilhelmshaven (part of the AEG group), which led ultimately to the company being absorbed into Olympia in 1959. Production continued for a time as the Brunsviga Division of Olympia, before coming to an end in the late 1960s. About half a million Brunsviga machines were produced over a period of almost eighty years.
Over the time, different logos were used, though the most famous is this one: "Gehirn von Stahl" , or "Steel Brain"
The "double" pinwheel machine as I have here, also known as the "twin" or "duplex", was developed by Brunsviga in around 1930. Its main purpose was to assist in calculations involving the conversion between rectangular and polar coordinates, particularly in surveying applications.
This "double 13R" is essentially two standard but inter-connected 13R machines mounted side-by-side on a common baseplate.
The two carriages are coupled together and move as one, but there are separate clearing controls for each register. To pre-set a dividend the numbers can be entered directly into the accumulator through a set of small rubber-tyred wheels at the front of the carriage. The levers at the lower left of each carriage section release the accumulator detents to allow the dials to turn more easily.
The rotors and counters of the two machines can be set individually to rotate in the same or opposite directions. There is a single rotor clearing lever on the left-hand side, which also engages the back-transfer mechanism. The counter clearing levers can be coupled to clear the corresponding rotor in the same manner as the "K" machines, but there is no master clearing control.
A common surveying problem involves measuring a series of angles and distances around a closed perimeter. These are converted to north-south and east-west distances, which should each sum to zero on returning to the starting point. To convert a distance and angle (r,Θ) into (x,y) coordinates the sine and cosine of the angle are set on the two rotors (from a book of tables, usually to 5 or 8 figures), and are multiplied simultaneously by the distance (via the turns of the crank). By setting the directions of rotation according to the quadrants of the angles, the results of the series of measurements can be accumulated automatically with the correct signs.