56 A Key to Civil Architecture: Or,

to arches over doors ; no deduction must be madefor them', because of the trouble. The dimensionsfor the height of such deductions must not be takenhigher than the springing of the arch.

As the measuring of chimnies in angles may beattended with, or seem a difficulty to those unac-quainted with the method; therefore I propose thefollowing rule for practice.

Multiply half the breadth of the front or breastby the height, and that product by the number ofhalf bricks contained in the half breast, (as to width)and divide the last product by 3, the content will bethe content in feet; out of which the opening mustbe deducted, the fame as in square chimnies. Seethe example.

Ft. In.

Suppose a chimney that standsin an angle to be 6 feet 6inc.in breadth, the height of thestory 10 feet, I place them asin the margin, and multiplyhalf the breast, which is 3 ft.

3 inches, and after multiplythat product by the numberof half bricks the half breastcontains, which we may sup-pose to be 8 ; aster I dividethe last product by 3, thenumber of half bricks in thestandard of brick - measure-ment, which gives the abovedimension 86 feet of reducedbrick-work; after this youmust deduct the opening, asin others chimnies. By the

10 o

260

24

20

18

3 3

6 o

30 o

3 2 6

o

8

o o

86

other angle chimnies may be measured.

above example all

By