a general name among mechanics, for almost all those pieces of their machines and instruments, that are double and perfectly alike. Thus, the checks of a printing press are its two principal pieces: they are placed perpendicular, and parallel to each other; serving to sustain the three sommers, viz. the head, shelves, and winter, which bear the spindle and other parts of the machine. See PRINTING Press.

The checks of a turner's lathe, are two long pieces of wood, between which are placed the puppets, which are either pointed or otherwise, serving to support the work and the mandrils of the workman. These two pieces are placed parallel to the horizon, separated from one another by the thickness of the tail of the puppets, and joined with tenons to two other pieces of wood placed perpendicularly, called the legs of the lathe.

Checks of the glazier's vice, are two pieces of iron joined parallel at top and bottom; in which are the axles, or spindles, little wheel, cushions, &c. whereof the machine is composed.

The checks of a mortar, or the brackets, in Artillery, are made of strong planks of wood, bound with thick plates of iron, and are fixed to the bed by four bolts; they rise on each side of the mortar, and serve to keep her at what elevation is given her, by the help of strong bolts of iron which go through both checks, both under and behind the mortar, betwixt which are driven quoins of wood; these bolts are called the bracket bolts; and the bolts which are put one in each end of the bed, are the traverse bolts, because with handspikes the mortar is by these traversed to the right or left.

in Ship-building, are two pieces of timber, fitted on each side of the mast at the top, serving to strengthen the masts there. The uppermost bail or piece of timber in the beak of a ship is called the cheek. The knees which fasten the beak head to the ship are called checks; and the sides of any block, or the sides of a ship's carriage of a gun, are also called checks.