the former course.--_Backing the worming._ The act of passing small
yarn in the holidays, or crevices left between the worming and edges of
the rope, to prevent the admission of wet, or to render all parts of
equal diameter, so that the service may be smooth.--_Wind backing._ The
wind is said to back when it changes contrary to its usual circuit. In
the northern hemisphere on the polar side of the trades, the wind
usually changes from east, by the south, to west, and so on to north. In
the same latitudes in the southern hemisphere the reverse usually takes
place. When it backs, it is generally supposed to be a sign of a
freshening breeze.

BACK. The outside or convex part of compass-timber. Also a wharf.

BACK, OF A SHIP. The keel and kelson are figuratively thus termed.

BACK, OF THE POST. An additional timber bolted to the after-part of the
stern-post, and forming its after-face.

BACK-BOARD. A board across the stern sheets of a boat to support the
back of passengers; and also to form the _box_ in which the coxswain
sits.

BACK-CUTTING. When the water-level is such that the excavation of a
canal, or other channel, does not furnish earth enough for its own
banks, recourse is had to _back-cutting_, or the nearest earth behind
the base of the banks.

BACK-FRAME. A vertical wheel for turning the three whirlers of a small
rope-machine.

BACK-HER. The order, in steam-navigation, directing the engineer to
reverse the movement of the cranks and urge the vessel astern.

BACKING. The timber behind the armour-plates of a ship.

BACK-O'-BEYOND. Said of an unknown distance.

BACK OFF ALL. The order when the harpooner has thrown his harpoon into
the whale. Also, to back off a sudden danger.

BACK-ROPE. The rope-pendant, or small chain for staying the
dolphin-striker. Also a piece long enough to reach from the cat-block to
the stem, and up to the forecastle, to haul the cat-block forward to
hook the ring of the anchor--similarly also for hooking the fish-tackle.
(_See_ GAUB-LINE.)

BACKS. The outermost boards of a sawn tree.

BACK-STAFF. A name formerly given to a peculiar sea-quadrant, because
the back of the observer was turned towards the sun at the time of
observing its zenith distance. The inventor was Captain Davis, the Welsh
navigator, about 1590. It consists of a graduated arc of 30 deg. united to
a centre by two radii, with a second arc of smaller radius, but measuring
6 deg. on the side of it. To the first