section_path: Mechanical devices/Calculating devices
section_name: Calculating devices
paragraph_text: Calculating devices
  
  John Napier introduced logarithms as a powerful mathematical tool. With the help of Henry Briggs their logarithmic tables embodied a computational advance that made calculations by hand much quicker. His Napier's bones used a set of numbered rods as a multiplication tool using the system of lattice multiplication. The way was opened to later scientific advances, particularly in astronomy and dynamics.
  
  At Oxford University, Edmund Gunter built the first analog device to aid computation. The 'Gunter's scale' was a large plane scale, engraved with various scales, or lines. Natural lines, such as the line of chords, the line of sines and tangents are placed on one side of the scale and the corresponding artificial or logarithmic ones were on the other side. This calculating aid was a predecessor of the slide rule. It was William Oughtred who first used two such scales sliding by one another to perform direct multiplication and division and thus is credited as the inventor of the slide rule in 1622.
  
  Blaise Pascal invented the mechanical calculator in 1642. The introduction of his Pascaline in 1645 launched the development of mechanical calculators first in Europe and then all over the world. Gottfried Leibniz, building on Pascal's work, became one of the most prolific inventors in the field of mechanical calculators; he was the first to describe a pinwheel calculator in 1685, and he invented the Leibniz wheel, used in the arithmometer, the first mass-produced mechanical calculator. He also refined the binary number system, the foundation of virtually all modern computer architectures.
  
  John Hadley was the inventor of the octant, the precursor to the sextant (invented by John Bird), which greatly improved the science of navigation.