Extraordinary German Brunsviga Doppler Calculator. First 1/3 s. XX.

German Brunsviga Calculating Machine with the possibility of carrying out two mathematical operations at the same time. It is in perfect condition. It has a nice metal case in glossy black enamel divided in two parts, with two numbering registers. Windlass and levers in silver metal alternating with the golden color of the numbering. The enamel needs a little review for usual marks of use, which undoubtedly give signs of the history of the piece. The "Doppler" had the particularity that it multiplied productivity, because with a single turn of the hand crank two different operations could be performed. The part on the left could add while the part on the right could subtract, or both could subtract or both could add at the same time, something incredible for the time! This type of machines are objects for science lovers. They have their origin back in the 17th century, when the first adding machines were built, characterized by using a gear-based operation, which arose to alleviate the work activity of those people engaged in accounting work. This German model of calculating machines was produced between 1906 and 1927 and was known as the windlass calculator. This type of machines were already very admired in its time, based on a system devised by Willigodt Odhner, the variant of the one developed by Leibniz in the XVIII century. A great number of copies would not be built, due to its high price and only 1500 copies would be produced. To acquire one of these machines is undoubtedly the object of true collectors! Measures: 30 x 21 cm; 44 cm (maximum width including levers)