Mensuration

The science which teaches the methods of calculating the magnitude of bodies, lines, and superfices.

Model

A miniature pattern of the whole or some part of a building, showing how the work is to be arranged and constructed.

Mortise

A sinkage, or recess, in a piece of timber to receive the tenon, or end, of another stick.

N

Naked Flooring

A term denoting the timbers of a floor, such as beams, girders, joists, etc, before the boards are laid upon them, or the furrings affixed beneath.

O

Out To Out

An expression denoting the magnitude of any body measured to the extreme outside.

Out Of Wind

An expression used by artificers to signify that the surface of a thing is a true and perfect plane. A squared piece of timber, which by any means has become twisted, is said to be winding.

P

Pale

A sharp-pointed stake of wood used for landmarks. etc.

Palisade

A fence or fortification made of stakes, sharpened, and driven firmly into the ground.

Parallel

In geometry, a term applied to lines or surfaces which run in the same direction, being at every point equidistant from each other.

Parallelogram

Any four-sided rectilinear figure whose opposite sides are parallel. The term usually denotes a figure greater in length than in width.

Partition

A wall dividing one room from another. When a partition is of great length, and is unsupported from beneath, it should be trussed: it is then called a trussed partition.

Pediment

The triangular part of a portico, or roof, which is terminated by the sloping lines of the roof. Pediments may be either triangular or segmental in contour. The term gable is nearly identical with pediment; but the latter term more properly applies to a gable when finished with an entablature, raking-mouidings, etc.

Pendentive Cradling

The timber-work which supports the laths and plaster of vaulted ceilings.

Perpendicular

A line, or surface, falling on another at right angles. The term also denotes a line at right angles with the horizon; although, in the latter case, the proper term is vertical.

Piles

Large unhewn timbers driven into the earth, upon the heads of which are laid the foundation-stones of large buildings, the piers of bridges, etc. Piles are used where the soil is too loose and spongy to insure the foundation against settlement without them. They are usually of oak or spruce, and are from 7 to 15 in. in diameter. They are sharpened at one end, and, if need be, shod with iron, and hooped at the top. They are then driven into the ground, as far as possible, by a machine, which lets a heavy weight fall upon their heads from a height of about 30 ft. Piles, when driven so far below the surface of the ground that water always remains over them, are quite impervious to decay. Nearly the entire city of Amsterdam is built on piles. The foundation-stones of the new Custom House in Boston rest on more than three thousand. They are driven at distances of 2 ft. from centres.

Pin

A piece of wood, commonly of chestnut or oak, sharpened at one end, and used to confine timbers together. Pins made by hand, and therefore left somewhat rough, are preferable to those made by a machine, as the latter, being nearly smooth and round, easily turn or work, when the wood about them has shrunk in drying; whereas those made by hand are polygonal, and, when driven into holes, their angles cut into the wood, and they are thereby effectually prevented from turning. Small pins are called pegs. The pins used in ship-building are made by machinery, and are called treenails.

Pitch

In carpentry, the term denotes the angle formed by the inclined sides of a roof. In a building where the extreme height from the top of the rafters at the ridge is one-third of the width of the building at the eaves, from "out to out," the roof is said to be one-third pitch; if one-quarter the width, one-quarter pitch. If it be 10 ft. from the top of the rafters to a line level with the eaves, it is 10-ft. pitch.

Plan

The representation of the horizontal section of a building, showing the disposition of the rooms by the arrangement of the partitions, etc. The word plan is quite extensive in its signification, and, as commonly used, denotes the general idea; hence, the design of the several parts of a building, whether as regards finish, arrangement of rooms, or the composition as a whole, may with propriety be termed its plan; but, among architects, the term more properly denotes a drawing exhibiting the form, arrangement, and size of the rooms on the several floors. A representation of a front or side is called an elevation.

Plank

A piece of timber of any length, having a width of more than 6 in., and from 2 to 6 in. thick. If less in thickness than 2 in., it is usually called a board. If the piece be less in width than 6 in., and not thin enough to be called a board, it is termed a joist. If thicker than 6 in., it is commonly called a timber.

Plate

The horizontal piece of timber that lies immediately on the top of the posts of a frame, or on the top of the walls of a i brick or stone building. Outter-\ plates are pieces of timber framed out from the side-walls for the support of the gutter.

Platform

An assemblage of timbers laid in a horizontal position, and covered with planks or boards, like a floor.

Plumb

A line perpendicular to, or at right angles with, the horizon. A level line and a plumb-line form a right angle when they are brought in contact. Hence, if one of the blades of a carpenter's framing-square be placed on the edge, in a level position, the other blade, being at right angles with it, will be a plumb-line.

Plumb-Rule

An instrument for determining plumb-lines.

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