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3A block containing three pulleys is denominated Trispastos; when the lower system has two pulleys, and the upper one three, Pentaspastos. A machine for raising heavier weights requires longer and stouter beams, and the pins for joining them at top, as well as the axle below, must be increased in proportion. Having premised this, the raising ropes lying loose, are first distributed; then to the shoulders of the machine are made fast the guys, which, if there be no place to which they can be otherwise firmly fixed, must be attached to sloping piles driven into the ground, and steadied by ramming the ground about them.
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