, or Plow, in Navigation, an ancient mathematical instrument, made of box or pear-tree, and used to take the height of the sun or stars, in order to find the latitude. This instrument admits of the degrees to be very large, and has been much esteemed by many artists; though now quite out of use.
PLUMB-Line, a term among artificers for a line perpendicular to the horizon.
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Entry taken from A Mathematical and Philosophical Dictionary, by Charles Hutton, 1796.
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