475. Masonry is estimated by the cubic foot, and 1. the perch; also by the square foot and the square yard.

1. Materials are usually estimated by cubic measure; the work by cubic or square measure.

2. A Perch of stone, or of masonry, is 161 ft. long, 1 ft. wide, and 1 ft. high, and is equal to 24.75 cu. ft.

3. When stone is built into a wall, 22 cu. ft. make a perch, 2 cu ft. being allowed for mortar and filling.

4. Embankments and Excavations are estimated by the cubic yard 5. A cubic yard of common earth is called a load.

6. Brickwork is generally estimated by the thousand bricks; sometimes in cubic feet. In walls, brick-work is estimated at the rate of a brick and a half thick.

7. North River bricks are 8 in. × 3 × 2; Maine bricks are 7 in. × 3 × 2; Philadelphia and Baltimore bricks are 8 in. × 43 × 28; and Milwaukee bricks 83 in. × 43 × 28.

8. In estimating material, allowance is made for doors, windows, and cornices.

9. In estimating the work, masons measure each wall on the outside, and ordinarily, no allowance is made for doors, windows, and corners; but sometimes an allowance of one-half is made, this being, however, a matter of contract.

476. To find the number of bricks in a cubic foot of masonry:

RULE.-I. Add to the face dimensions of the kind of bricks used the thickness of the mortar or cement in which they are laid, and compute the area.

II. Multiply this area by the quotient of the thickness of the wall divided by the number of bricks of which it is composed, the product will be the volume of a brick and its mortar in cubic inches.

III. Divide 1728 by this volume, and the quotient will be the number of bricks in a cubic foot.

477. 1. of wall 12 thick ?

How many Milwaukee bricks in a cubic foo in. wide, laid in courses of mortar

of an inch

OPERATION.

8.5+.25 8.75 in. = length of brick and joint. 2.375+.25

2.625 in.: thickness of brick and joint.

8.75 x 2.625 = 22.96875 sq. in. area of its face.

=

12.753 (number of bricks in width of wall) = 4.25 in. = wiath of brick and mortar.

22.96875 × 4.25 = = 97.617+ = cubic inches in a brick.

1728÷ 97.617+ = 17.7+ = number of bricks in a cubic foot.

2. How many bricks, 8 in. × 4 × 2, will be required to build a wall 42 ft. long, 24 ft. high, and 16 in. thick, laid in courses of mortar of an inch thick?

3. How many perches of stone, laid dry, will build a wall 60 ft. long, 163 ft. high, and 18 in. thick?

RULES.-1. Multiply the number of cubic feet in the wall, or work to be done, by the number of bricks in a cubic foot; the product will be the number of bricks required.

2. Divide the number of cubic feet in the work to be done by 24.75; the quotient will be the number of perches.

4. How many perches of masonry in a wall 120 ft. long, 6 ft. 9 in. high, and 18 in. thick?

5. How many bricks in the four walls of a square house 36 ft. long, 24 ft. high, and 12 in. thick, allowing 224 cu. ft. for doors and windows, one half for the corners, and of an inch for each course of mortar?

6. At $.56 a cu. yd., what will it cost to remove an embankment 240 ft. long, 38 ft. wide, and 8.5 ft. high?

7. Find the cost of digging and walling the cellar of a house, whose length is 41 ft. 3 in., and width 33 ft.; the cellar to be 8 ft. deep, and the wall 1 ft. thick. The excavating will cost $.50 a load, and the stone and mason work $3.75 a perch.

8. How many perches of stone will be required to enclose a lot 16 rd. long and 12 rd. wide, with a wall 6 ft. high and 3 ft. thick, allowing one-half for the corners ?

9. A street 650 ft. long and 72 ft. wide, averages 4.5 ft. below grade. Find the cost of filling it in, at $.42 a cu.

.yd.? 10. What will be the cost of building a wall 60 ft. long, 213 ft. high, and 17 in. thick, of Philadelphia bricks, laid in courses of mortar of an inch thick, at $12 per M.?

11. How many cubic feet of masonry in the wall of a cellar 37 ft. long, 26 ft. wide, and 9 ft. deep, the wall being 2 ft. thick, allowing one-half for the corners ; and what will be the cost, at $3.85 a perch?

BOARDS AND TIMBER.

478. A Board Foot is 1 ft. long, 1 ft. wide, and 1 inch thick. Hence 12 board feet make 1 cubic foot. Board feet are changed to cu. ft. by dividing by 12, and cubic feet are changed to board feet by multiplying by 12.

1. In Board Measure all boards are assumed to be 1 in. thick. 2. Lumber and Sawed Timber, such as plank, scantling, joists, etc., are usually estimated in board measure.

3. Hewn and Round Timber are commonly estimated in cubic

measure.

479. When lumber is not more than 1 inch thick : RULE.-Multiply the length in feet by the width in inches, and divide the product by 12.

480. When more than 1 inch thick:

RULE.-Multiply the length in feet by the width and thickness in inches, and divide the product by 12.

1. If one of the dimensions is inches, and the other two are feet, the product will be board feet.

2. If a board tapers regularly, multiply the length by the mean width, found by taking half the sum of the two ends.

481. 1. Find the contents of a board 15 ft. long and 8 in. wide.

OPERATION.-15 × 8÷ 12 = 10 board feet.

2. What are the contents in board measure of a joist 16 ft. long, 10 in. wide, and 3 in. thick?

OPERATION.-3 × 10 × 16 ÷ 12 = 40 board feet.

3. How many board feet in 4 boards 16 ft. long, 10 in. wide?

4. How many board feet in 2 joists 17 ft. long, 11 in. wide, and 3 in. thick ?

5. Find the contents of a board 19 ft. long, 1 ft. 8 in. wide at one end, and 14 in. at the other.

OPERATION.—20 in. +14 in÷2=17 in ; 18 × 17÷12=251 board ft.

6. Find the cost of 5 boards 12 ft. long, 17 in. wide at one end and 11 in. at the other, at 6 cents a square foot.

7 Find the cost of 10 planks, each 15 ft. long, 16 in. wide, and 3 in. thick, at $2.25 per hundred feet.

8. What length of board 9 in. wide contains 8 board ft.? OPERATION.-144 × 8÷9=128; 128÷12=10} ft., the length.

9. What length may be cut from a board 15 ft. long and 20 in. wide, so as to leave 15 board feet?

10. What must be the width of a board 16 ft. long to contain 12 board feet?

OPERATION.-16 ft.=192 in.; 144 × 12÷192-9 in., the width.

11. What must be the width of a piece of board 5 ft. 3 in. long, to contain 7 square feet?

12. Find the cost of 3 pieces of timber, each 26 ft. long and 6 in. by 9 in., at $1.75 per hundred board feet.

13. Find the cost of 8 pieces of scantling, 3 in. by 4 in. and 14 ft. long, at $9.50 per thousand board feet.

14. What length of a piece of timber 6 in. by 9 in., will contain 3 cubic feet?

OPERATION. -1728 × 3 :9 × 696 ; 96:12=8 ft., the length.

15. A piece of timber is 10 in. by 16 in.; what length of it will contain 15 cubic feet?

16. What amount of inch lumber will make a box 4 ft. by 3 ft. 6 in. by 2 ft. 6 in. on the outside?

Find the cost of the following:

17. Of 36 boards, 12 ft. long, 11 in. wide, @ $24 per C. 18. Of 16 planks, 14 feet long, 10 in. wide, and 3 in. thick, @ $16ł per M.

19. How many board feet in a stick of timber 36 ft. long, 10 in. thick, 12 in. wide at one end and 9 in. wide at the other end? How many cubic feet?

20. Make a bill for lumber bought by John Osborn of Geo. Mason & Co., of St. Paul, Sept. 20, 1875, as follows.