Slide chart

A slide chart is a hand-held device, usually of paper, cardboard, or plastic, for conducting simple calculations or looking up information. A circular slide chart is sometimes referred to as a wheel chart or Volvelle.
Unlike other hand-held mechanical calculating devices such as slide rules and addiators, which have been replaced by electronic calculators and computer software, wheel charts and slide charts have survived to the present time. There are a number of companies who design and manufacture these devices.
More information on the Wikipedia page ; the page on the slide rule is . There are various websites including the Slide Rule Museum.
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