=22. Stone masonry= is generally measured by the perch; in some
sections of the United States, however, measurement by the cord is
preferred, but the best method (as being invariable) is by the cubic
yard. In estimating by the perch, it is necessary to state how much
the perch is taken at, whether 24¾ or 25 cubic feet. Note should also
be made in regard to corners and deduction for openings. In most
localities it is not customary to deduct openings under a certain size,
and corners are usually measured twice.
=23.= Rough stone from the quarry is generally sold under two
classifications; namely, _rubble_ and _dimension stone_. =Rubble=
consists of pieces of irregular size, such as are most easily obtained
from the quarry, up to 12 inches in thickness by 24 inches in length.
Stone ordered of a certain size, or to square over 24 inches each way
and to be of a particular thickness, is called =dimension stone=.
Rubble masonry and stone backing are generally figured by the perch
or cubic yard. Dimension-stone footings are measured by the square
foot unless they are built of large, irregular stone, in which case
they are measured the same as rubble. Ashlar work is always figured by
the superficial foot; openings are usually deducted, and the jambs are
measured in with the face work. Flagging and slabs of all kinds, such
as hearths, treads for steps, etc., are measured by the square foot;
sills, lintels, molding, belt courses, and cornices, by the linear
foot; and irregular pieces, by the cubic foot. All carved work is done
at an agreed price by the piece.