Schickard Machine

One of the first mechanical calculating engines was developed in 1623 by the German mathematician, astronomer, geodesist, as well as professor of Hebrew and Aramaic, Wilhelm Schickard (1592-1635) for his friend Johannes Kepler. In a letter to Kepler dated September 1623, Schickard wrote: "The same thing which you have done by hand calculation, I have just recently tried to do in a mechanical way. I have constructed a machine which automatically reckons together the given numbers in a moment, adding, subtracting, multiplying and dividing."The next letter contained sketches of the machine, and a third told the sad story of the machine being destroyed by fire.

Since the machine was never rebuilt until its rediscovery by Kepler specialist Franz Hammer in 1957, it is often Blaise Pascal who is credited with the invention of the first adding machine with automatic carry for his “Pascaline” (1642). Schickard’s calculator was the first counting mechanism that added and subtracted with automatic carry of tens and with six digits, shifting a 1 to the left when the sum of a certain column became greater than 9, and ringing a clock at each overflow (hence the machine was often referred to as “calculating clock”). Addition was performed by turning the dials on the lower part of the machine. These dials were connected with internal wheels, with teeth on their circumference, causing a carry as the wheel passed from 9 to 0. Subtraction was performed by reversing the wheel. Multiplication and division were more complicated, since the user of the machine had to use a set of revolving cylindrical Napier Bones to determine the partial product and feed it into the 6 digits for addition. However, it was discovered later that an even earlier attempt at constructing a calculating engine had been made by none other than Leonardo da Vinci. In 1967, some of his notes were found in the National Museum of Spain, which included a description of a machine bearing a certain resemblance to Pascal's machine. A model of da Vinci's machine was made with the help of these notes.

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Source: http://world-information.org/wio/program/objects/1037128808