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An abacus (pl.: abaci or abacuses), also called a counting frame, is a hand-operated calculating tool which was used from ancient times in the ancient Near East, Europe, China, and Russia, until the adoption of the Hindu–Arabic numeral system. [1] An abacus consists of a two-dimensional array of slidable beads (or similar objects). In their ...
The Late Roman hand abacus shown here as a reconstruction contains seven longer and seven shorter grooves used for whole number counting, the former having up to four beads in each, and the latter having just one. The rightmost two grooves were for fractional counting. The abacus was made of a metal plate where the beads ran in slots.
Mary Anderson was born in germany Hill Plantation, Greene County, Alabama, at the start of Reconstruction in 1866. Her parents were John C. and Rebecca Anderson. Anderson was one of at least two daughters. The other daughter was Fannie, who remained close to Anderson all her life.
After the development of the abacus, no further advances were made until John Napier devised his numbering rods, or Napier's Bones, in 1617. Various forms of the Bones appeared, some approaching the beginning of mechanical computation, but it was not until 1642 that Blaise Pascal gave us the first mechanical calculating machine in the sense ...
The first abacus pictured below (fig. 5) is decorated with simple mouldings and ornaments, common during the 12th century, in Île-de-France, Normandy, Champagne, and Burgundy regions, and from the choir of Vézelay Abbey (fig. 6). Figure 7 shows a circular abacus used at windows in the side chapels of Notre Dame de Paris. Towards the end of ...
Horace King (sometimes Horace Godwin) (September 8, 1807 – May 28, 1885) was an African-American architect, engineer, and bridge builder. [1] King is considered the most respected bridge builder of the 19th century Deep South, constructing dozens of bridges in Alabama, Georgia, and Mississippi. [2]
Encyclopedia of Alabama (2008) Online coverage of history, culture, geography, and natural environment. online; Rogers, William Warren, Robert David Ward, Leah Rawls Atkins, and Wayne Flynt. Alabama: The History of a Deep South State (3rd ed. 2018; 1st ed. 1994), 816pp; the standard scholarly history online older edition; online 2018 edition
These new surroundings hastened the development of an existing idea: an adding machine. His new job gave him the opportunity to build his prototype. Accuracy was the foundation of his work. He made his design drawings on metal plates to prevent distortion. Burroughs filed his first patent for the invention of a "calculating machine" in 1885. It ...