Wilhelm Schickard was born on April 22, 1592, and died on October 24, 1635. He was a German professor who taught Hebrew and astronomy. In the second half of the 20th century, Franz Hammer, a writer who studied the life of Johannes Kepler, claimed that Schickard had created drawings of a calculating clock. These drawings were discovered in two letters Schickard wrote to Kepler in 1623 and 1624. These letters were not known to exist until Hammer found them, and they showed that Schickard’s design came 20 years before Pascal’s calculator was made public.

Hammer said that because these letters were lost for 300 years, people had mistakenly credited Blaise Pascal as the first inventor of a mechanical calculator. However, after further study, it was found that Schickard’s designs had been published at least once every century since 1718. His machine was not fully complete and needed extra parts, such as more wheels and springs. It also used a single-tooth carry mechanism, which did not work well in calculating clocks.

Schickard’s machine was one of the first designs for direct-entry calculating machines in the 17th century. Other similar designs were made by Blaise Pascal, Tito Burattini, Samuel Morland, and René Grillet. Schickard’s machine was special because it combined a clever system of rotated Napier’s bones for multiplication with an early design for an adding machine. The adding machine used rotating knobs for input, and numbers in windows showed the results.

Some scholars, like Taton, argued that Schickard’s work did not influence later mechanical calculators. However, later devices, such as Morland’s multiplying and adding tools, Caspar Schott’s Cistula, Grillet’s machine arithmétique, Perrault’s rhabdologique, and the Bamberger Omega, followed a similar path. These devices used a combination of Napier’s bones and adding machines, just like Schickard’s design.

Schickard is sometimes called "the father of the computer age."

Life

Wilhelm Schickard was born in Herrenberg and studied at the University of Tübingen. He earned his first degree, a B.A., in 1609 and a M.A. in 1611. He studied theology and languages from the East at Tübingen until 1613. In 1613, he became a Lutheran minister and continued working with the church until 1619, when he was given the position of professor of Hebrew at the University of Tübingen.

Schickard studied many different subjects and taught biblical languages, such as Aramaic and Hebrew, at Tübingen. In 1631, he was appointed professor of astronomy at the University of Tübingen. His research included astronomy, mathematics, and surveying. He invented several machines, including one for calculating astronomical dates and one for studying Hebrew grammar. He made important improvements in mapmaking, creating maps that were more accurate than those made before.

In addition to his other work, Schickard was a skilled engraver of wood and copper plates.

Wilhelm Schickard died from the bubonic plague in Tübingen on 23 or 24 October 1635. In 1651, Giovanni Riccioli named a lunar crater after him, calling it Schickard.

Political theory

In 1625, a scholar named Schickard, who studied Hebrew and Jewish texts, published an important book called Mishpat ha-melek, Jus regium Hebraeorum. The title of the book is written in both Hebrew and Latin, meaning "The King's Law." In this book, Schickard used the Talmud and writings from Jewish religious leaders to examine ancient Hebrew ideas about government. He argued that the Bible supports the idea of a king ruling a country.

Drawings of a calculating clock

In 1623 and 1624, he wrote two letters to Kepler about his design and construction of a machine he called an “arithmeticum organum” (“arithmetical instrument”), which later became known as a Rechenuhr (calculating clock). The machine was created to help with the four basic arithmetic operations: addition, subtraction, multiplication, and division. Schickard suggested it could be used to calculate complex astronomical tables. The machine could add and subtract six-digit numbers, and it rang a bell if the numbers were too large for its capacity. The adding machine at the base was meant to help with the difficult task of adding or multiplying large numbers. It used a clever setup of rotatable Napier's bones. It also had a special "memory register" to keep track of intermediate steps. Schickard mentioned that the machine worked, but he asked a professional clockmaker, Johann Pfister, to build a finished version. Unfortunately, the machine was destroyed in a fire before it was completed. Schickard stopped his project soon after. He and his family died in 1635 from the bubonic plague during the Thirty Years' War.

Schickard's machine used strong, heavy clock wheels to prevent damage from operator input. Each digit used a display wheel, an input wheel, and an intermediate wheel. When carrying over numbers, all these wheels connected with the wheels of the next digit.

The Institute for Computer Science at the University of Tübingen is named the Wilhelm-Schickard-Institut für Informatik in his honor.

There has been debate about who invented the mechanical calculator first. Schickard’s design was created earlier but was never completed and had serious flaws. Pascal’s design was made later but worked well.

In 1718, a biographer of Kepler named Michael Gottlieb Hansch published letters from Schickard that described the calculating machine. His priority was also noted in an 1899 publication, the Stuttgarter Zeitschrift für Vermessungswesen. In 1957, Franz Hammer, a Kepler biographer, announced that Schickard’s drawings of the calculating clock were made 20 years before Pascal’s work.

In 1960, Bruno von Freytag-Löringhoff built a replica of Schickard’s machine but had to improve its carry mechanism.

— Michael R. Williams, History of Computing Technology, IEEE (1997)

Pascal’s invention was likely independent because "it is almost certain that Pascal would not have known of Schickard’s machine." Pascal realized that a single-tooth gear would only work for short carries. For longer carries, the gears could break.

The two machines were different in purpose. Pascal’s machine was mainly for addition and subtraction (using complementary numbers). Schickard’s machine could sometimes jam if a carry needed to move across too many dials, but it could subtract by reversing the input dials, which Pascal’s machine could not do. Experiments with replicas show that when a jam occurred, the operator could help the machine complete the carry. This was not as efficient as Pascal’s machine but was not a major problem. Schickard’s machine also had a bell that warned if the result was too large for the dials, which Pascal’s machine did not have.

Pascal created his machine to help his father with calculations and later for commercial use. Schickard’s machine was designed to help with multiplication (using Napier’s bones to calculate partial products, a method also useful for division).

Works

A multicolored fire fell from a clear sky and was observed in Tübingen in 1623. Published by Theodoricus Werlin, Tübingen: 1623.