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Movements, leaders, victories and the continuing fight for equality.
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In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
The Arithmaurel was a mechanical calculator that had a very intuitive user interface, especially for multiplying and dividing numbers because the result was displayed as soon as the operands were entered. It was first patented in France by Timoleon Maurel, in 1842.[1] It received a gold medal at the French national show in Paris in 1849.[2] Its complexity and the fragility of its design prevented it from being manufactured.[3]
Its name came from the concatenation of Arithmometer, the machine that inspired its design and of Maurel, the name of its inventor. The heart of the machine uses one Leibniz stepped cylinder driven by a set of differential gears.[4]
Timoleon Maurel patented an early version of his machine in 1842,[1] he then improved its design with the help of Jean Jayet and patented it in 1846.[5] This is the design that won a gold medal at the Exposition nationale de Paris in 1849.
Winnerl, a French clockmaker, was asked to manufacture the device in 1850, but only thirty machines were built because the machine was too complex for the manufacturing capabilities of the time.[6] During the first four years, Winnerl was not able to build any of the 8 digit machines (a minimum for any professional usage) that had been ordered while Thomas de Colmar delivered, during the same period, two hundred 10 digit Arithmometers and fifty 16 digit ones.[7]
None of the machines that were built and none of the machines described in the patents could be used at full capacity because the capacity of the result display register was equal to the capacity of the operand register (for a multiplication, the capacity of the result register should be equal to the capacity of the operand register augmented by the capacity of the operator register).
Following is a description of one of the two machines introduced in the 1846 patent.[5] It has a capacity of five digits for the operator and ten digits for the operand and the result registers.
All the registers are located on the front panel, the reset mechanism is on the side.
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The Arithmaurel was a mechanical calculator that had a very intuitive user interface, especially for multiplying and dividing numbers because the result was displayed as soon as the operands were entered. It was first patented in France by Timoleon Maurel, in 1842. It received a gold medal at the French national show in Paris in 1849. Its complexity and the fragility of its design prevented it from being manufactured. Its name came from the concatenation of Arithmometer, the machine that inspired its design and of Maurel, the name of its inventor. The heart of the machine uses one Leibniz stepped cylinder driven by a set of differential gears.
This article presents a detailed timeline of events in the history of computing: from prehistory until 1949. For narratives explaining the overall developments, see History of computing.
A mechanical calculator, or calculating machine, is a mechanical device used to perform the basic operations of arithmetic automatically, or a simulation like an analog computer or a slide rule. Most mechanical calculators were comparable in size to small desktop computers and have been rendered obsolete by the advent of the electronic calculator and the digital computer. In 1642, Blaise Pascal invented the first operational mechanical calculator with better tens-carry. Concerned about his father's exhausting work as tax collector in Rouen, Pascal designed the Pascaline to help with the large amount of tedious arithmetic required. In 1672, Gottfried Leibniz started designing an entirely new machine called the Stepped Reckoner. It used a stepped drum, built by and named after him, the Leibniz wheel, was the first two-motion design, the first to use cursors (creating a memory of the first operand) and the first to have a movable carriage. Leibniz built two Stepped Reckoners, one in 1694 and one in 1706. The Leibniz wheel was used in many calculating machines for 200 years, and into the 1970s with the Curta hand calculator, until the advent of the electronic calculator in the mid-1970s. Leibniz was also the first to promote the idea of a pinwheel calculator. During the 18th century, several inventors in Europe were working on mechanical calculators for all four species. Philipp Matthäus Hahn, Johann Helfreich Müller and others constructed machines that worked flawlessly, but due to the enormous amount of manual work and high precision needed for these machines they remained singletons and stayed mostly in cabinets of curiosity of their respective rulers. Only Müller's 1783 machine was put to use tabulating lumber prices; it later came into possession of the landgrave in Darmstadt. Thomas' arithmometer, the first commercially successful machine, was manufactured in 1851; it was the first mechanical calculator strong enough and reliable enough to be used daily in an office environment. For forty years the arithmometer was the only type of mechanical calculator available for sale until the industrial production of the more successful Odhner Arithmometer in 1890. The comptometer, introduced in 1887, was the first machine to use a keyboard that consisted of columns of nine keys (from 1 to 9) for each digit. The Dalton adding machine, manufactured in 1902, was the first to have a 10 key keyboard. Electric motors were used on some mechanical calculators from 1901. In 1961, a comptometer type machine, the Anita Mk VII from Sumlock, became the first desktop mechanical calculator to receive an all-electronic calculator engine, creating the link in between these two industries and marking the beginning of its decline. The production of mechanical calculators came to a stop in the middle of the 1970s closing an industry that had lasted for 120 years. Charles Babbage designed two kinds of mechanical calculators, which were too sophisticated to be built in his lifetime, and the dimensions of which required a steam engine to power them. The first was an automatic mechanical calculator, his difference engine, which could automatically compute and print mathematical tables. In 1855, Georg Scheutz became the first of a handful of designers to succeed at building a smaller and simpler model of his difference engine. The second one was a programmable mechanical calculator, his analytical engine, which Babbage started to design in 1834; "in less than two years he had sketched out many of the salient features of the modern computer. A crucial step was the adoption of a punched card system derived from the Jacquard loom" making it infinitely programmable. In 1937, Howard Aiken convinced IBM to design and build the ASCC/Mark I, the first machine of its kind, based on the architecture of the analytical engine; when the machine was finished some hailed it as "Babbage's dream come true".
The arithmometer (French: arithmomètre) was the first digital mechanical calculator strong and reliable enough to be used daily in an office environment. This calculator could add and subtract two numbers directly and perform long multiplications and divisions effectively by using a movable accumulator for the result. Patented in France by Thomas de Colmar in 1820 and manufactured from 1851 to 1915, it became the first commercially successful mechanical calculator. Its sturdy design gave it a strong reputation for reliability and accuracy and made it a key player in the move from human computers to calculating machines that took place during the second half of the 19th century. Its production debut of 1851 launched the mechanical calculator industry which ultimately built millions of machines well into the 1970s. For forty years, from 1851 to 1890, the arithmometer was the only type of mechanical calculator in commercial production, and it was sold all over the world. During the later part of that period two companies started manufacturing clones of the arithmometer: Burkhardt, from Germany, which started in 1878, and Layton of the UK, which started in 1883. Eventually about twenty European companies built clones of the arithmometer until the beginning of World War I.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →The Greenwood District.
