Rotary electro-mechanical desktop calculator, 1958. The rotary calculating mechanism keeps the mechanism engaged and in motion at all times. Linear mechanisms, such as the oscillating rack, move in one direction, then must stop and disengage before restoring to its original position for the next machine cycle. Rotary calculators are usually faster for multiplication and division tasks than other systems.
Saldorita
Swedish manual adding machine. The Saldorita is rather rare among Swedish calculators. Two models were manufactured around 1937 by the Saldorita company in Motala. Save for the lever setting, the construction is similar to the early printing Addo models which had stylus setting. The Saldorita adder never became a commercial success despite of the printing mechanism. The housing is of bakelite.
Mercedes Euklid was established in 1905 in Germany. This first Model is from 1905 and is lever operated. It provided the ability to perform complex calculations. Beautifully built. Numbers are input via levers and calculated by turning the crank clockwise for adding and counter-clockwise for subracting.
The Addo company was founded in 1917. It manufactured both calculators and typewriters. In 1960s the company was incorporated in the Facit concern. This rare adding machine is stylus and lever operated while a handle had to be pulled to obtain adding and cumulative adding results in both a mechanical display (below) and onto the paper roll of the printing device. There are only a few of these beautiful machines left in museums and one or two private collections.
Thomas Arithmometer
Invented by Charles Xavier Thomas de Colbar in 1820. Fifteen hundred models were sold over the next thirty years, chiefly to banks, insurance companies, and other businesses. Capable of performing addition, subtraction, multiplication and division. The Thomas Arithmometers were produced and sold in Europe and the United States well into the 20th century, and were widely imitated and marketed by many manufacturers.
Dating to 1895, the Saxonia calculator was a commercial device for addition and multiplication based on the Thomas de Colmar arithmometer (see above). It was one of 14 such machines manufactured by Arthur Burkhardt, the founder of the German calculating machine industry.
Logarithmic Slide Drum 'Loga'
Very popular among bookkeepers, math teachers and engineers: the slide rule calculating cilinder. Very complicated analogous calculations could be performed in little time and with the utmost accuracy.
Curta Models 1 and 2
Small, hand-cranked mechanical calculator. Model 1 was introduced in 1948. It had a brilliantly compact design, a small cylinder that fit in the palm of the hand. The Curta's design is a variant of Gottfried Leibniz's Arithmometer, accumulating values on cogs, which are added or complemented by a stepped drum mechanism. Invented by Curt Herzstark while he was a prisoner in the Buchenwald concentration camp.
