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Dictionary

Classical Architecture

 

Architecture Dictionary: J

 

JACK ARCH

One whose thickness is only of one brick.

JACK PLANE

A plane about eighteen inches long, used in taking off the rough surface left by the saw or that of the axe, and of taking off large protuberant parts, to prepare the stuff for the trying plane.

JACK RAFTER. See Hir ROOF.

JACK RIBS.

Those in a groin, or in a polygonally-domed ceiling, that are fixed upon the hips. JACK TIMBER. Any one interrupted in its length, or cut short.

JAMB LININGS. The two vertical linings of a doorway which are usually of wood.

JAMB POSTS. Those introduced on the side of a door, to which tbe jamb linings are fixed. They are particularly used when partitions are of wood.

JAMB STONES. In stone walls are those which are employed in building the sides of apertures, in which every alternate stone should go entirely through the thickness of the wall.

JAMBS. (Fr.) The sides of an aperture which connect the two sides of a wall.

JERKIN HEAD

The end of a roof not hipped down to the level of the opposite adjoining walls, the gable being carried higher than the level of those walls.

Jib DOOR

A door so constructed as to have the same continuity of surface with that of the partition or wall in which it stands. Its use is to preserve an unbroken surfkee in an apartment where one door only is wanted nearer to one end of a room than another, and generally for the purpose of preserving uniformity.

JOGGLE

The joint of two bodies so constructed as to prevent them sliding past each other, by the application of a force in a direction perpendicular to the two pressures by which they are held together. Thus the struts of a roof are joggled into the truss posts and into the rafters. When confined by mortise and tenon, the pressure which keeps them together is that of the rafter and the reaction of the truss post. Tbe term is also used in masonry to signify the indentation made in one stone to receive the projection in another, so as to prevent all sliding on the joints. This may be also accomplished by means of independent pieces of material let into the adjacent stones.

JOGGLE PIECE. The truss post in a roof when formed to receive a brace or strut with a joggle.

JOINER

The artisan who joins wood by glue, framing, or nails, for the finishings of a building.

JOINERY

The practice of framing or joining wood for the internal and external finishings of houses; thus the covering and lining of rough walls, the covering of rough timbers, the manufacture of doors, shutters, sashes, stairs, and the like, are classed under the head of joinery.

JOINT

The surface of separation between two bodies brought into contact and held firmly together, either by some cementing medium, or by the weight of one body lying on another. A joint, however, is not merely the contact of two surfaces, though the nearer they approach the more perfect the joint. In masonry, the distances of the planes intended to form the joint is comparatively considerable, because of the coarseness of the particles which enter into the composition of tbe cement.

JOINTER

In joinery is the largest plane used by the joiner in straightening the face of the edge of the stuff to be prepared. In bricklaying, it is a crooked piece of iron forming two curves of contrary flexure by its edges on each side, and is used for drawing, by the aid of the jointing rule, the courting ana vertical joints of the work.

JOINTING RULE

A straight edge used by bricklayers for the regulation of the direction and course of the jointer in the horizontal and vertical joints of brickwork.

JOISTS

(Fr. Joindre.) The timbers whereto the boards of a floor or the laths for a ceiling are nailed. They rest on the walls or on girders; sometimes on both. When only one tier of joists is used, the assemblage is called gingle-flooring; when two, doubleflooring.

JUPPERS

An obsolete term for pieces of timber four or five inches square. JuMr. An abrupt rise in a level course of brickwork or masonry to accommodate the work to the inequality of the ground. Also in quarrying, one among tbe various names given to the dislocations of the strata in quarries.

JUMFER. A long iron chisel used by masons and miners.

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