### September 2 - Blog Post 2 (An Early Computer)

Wilhelm Schickard, born on April 22, 1592 was a German professor of Hebrew, who later became a professor of Astronomy. Schickard was born in the small south German town, Herrenberg. He was educated at nearby Tubingen, in a Protestant theological seminary known as Tubinger Stift. He obtained a Bachelor's Degree in 1609 and a Master's Degree in Theology 2 years later. He became a Lutheran minister in 1613; furthermore, he continued ministering until 1619. He was appointed Professor of Hebrew in 1619 at the University of Tubingen. After 1631, he later became a Professor of Astronomy, including analytical fields such as Mathematics and Computer Science ("History of Computers.. Wilhelm Schickard.").

He is credited for inventing the first true mechanical calculator in 1623, known as The "Calculating Clock". The name "Calculating Clock" is somewhat misleading as it does not tell time. However, he became famous in the second part of the 20th century after Dr. Franz Hammer (a biographer of Johannes Kepler) claimed that letters written by Schickard to Johannes Kepler in 1623 and 1624 included the drawings of a calculating clock, twenty years before Pascals' invention. In the letters, Schickard noted his machine as *Rechen Uhr* - Calculating Clock. Unfortunately, the Calculating Clock did not make it to the present day. However, the letters sent from Schickard to Johannes Kepler which includes sketches of the machine were found ("Schickard's Calculating Clock." ).

It is said to be of the size of a typewriter with the ability of performing basic arithmetic such as adding, subtracting, multiplying, and dividing. The calculating clock is based on six-digit numbers; in addition, it made a bell-sound to note an overflow. Schickard invented a very complicated machine, especially considering that it was the first of its kind.

History-computer.com illustrates an example on how to use the Calculating Clock. "Let's make a simple multiplication with the machine, for example 524 x 48. First we have to rotate the rightmost cylinder to 4, next cylinder to 2, and the third from right to 5 (the multiplicand is 524). Then we have to open the windows on the 8th row (units of the multiplier are 8) and we will see in the windows the first intermediate result (4192). We have to enter the 4192 in the calculating mechanism. Then we have to open the windows on the 4th (tens of multiplier are 4) row and to see the second intermediate result-20960, which we have to enter to the calculating mechanism, and we will have the result-25152" ("History of Computers.. Wilhelm Schickard.").

As noted, Shickard's invention was lost. However, the knowledge of the Schickard's calculating clock was recovered in the twentieth century. Professor Bruno Baron von Freytag Loringhoff, of the University of Tubingen, Germany, used the sketch in the letters written by Schickard to Johannes Kepler to build a replica of Schickard's machine. The machine was donated to the Computer Museum of America.

### Citation

"History of Computers and Computing, Mechanical Calculators, Pioneers, Wilhelm Schickard."

History of Computers and Computing, Mechanical Calculators, Pioneers, Wilhelm Schickard. N.p., n.d. Web. 02

Sept. 2012. http://history-computer.com/MechanicalCalculators/Pioneers/Schickard.html.

"Schickard's Calculating Clock." Schickard's Calculating Clock Research & Articles. N.p., n.d. Web. 02

Sept. 2012. https://www.bookrags.com/checkout/?p=gale&u=schickards-calculating-clock-wcs.