Wilhelm Schickard was born in Herrenberg, Germany, in 1592, and became a renowned astronomer, mathematician, linguist, and Lutheran minister. He is credited with building in 1623 the world's first true mechanical calculator, his "calculating clock" (a somewhat misleading moniker, as the device did not tell time). Schickard's hand-powered calculator was quite sophisticated, especially considering that it was the first of its kind. It was about the size of a typewriter and could add, subtract, multiply, and divide. It operated on six-digit numbers and rang a bell to announce overflow (i.e., a calculation result too large to represent on its readout).
Calculating aids akin to the slide rule had been built before (e.g., Napier's rods), so what justifies calling Schickard's clock the first "true" calculator? In using Napier's rods and similar devices, the operator rotates marked cylinders or slides marked sticks past each other and interprets the resulting relationship of one set of marks to another. Such devices are inherently passive; all their motions depend on the judgment of the human operator. This is also true of the abacus, the most ancient calculating aid. In Shickard's clock, however, numbers are represented by the states of physical devices (gears), and these devices interact with each other mechanically. In this machine the rules of arithmetic are modeled by the cause-and-effect behaviors of physical devices for the first time; the numbers stored in the calculator actively modify one another. This innovation is the conceptual basis of all modern computing.
Leonardo da Vinci had sketched a workable mechanical calculator a century before Schickard, but there is no evidence that his device was ever actually built. Schickard's clock was built and actually functioned.
Shickard's invention was lost when he and his entire family were killed by plague in the mid-1630s. It might not have been if the copy he was having built for the great astronomer Kepler had survived, but an unlucky fire destroyed the workshop while the copy was being made. Schickard's own copy of the machine has been lost. Only in the twentieth century was knowledge of the Schickard calculating clock recovered. In the 1950s a sketch by Schickard of his mechanism was discovered among Kepler's papers at the Pulkovo Observatory near Leningrad, Russia. Profressor Bruno Baron von Freytag Loringhoff, of the university of Tübingen, Germany, used the sketch to build a working copy of Schickard's machine. This device now resides in the Computer Museum of America.
This is the complete article, containing 402 words
(approx. 1 page at 300 words per page).
