EXAMPLES.

1. What is the solidity of an anchor ring, whose inner diameter is 8 inches, and thickness in metal 3 inches?

=

8+3×29.8696 — 11 × 1.52 × 9.8696—11×2.25× 9.8696=24.75 × 9.8696=244.2726=solidity required. · 2. The inner diameter of a cylindric ring is 18 inches, and its thickness 4 inches; what is the solidity?

Ans. 868.5248. 3. Required the solidity of a cylindric ring, whose thickness is 2 inches, and its inner diameter 12.

Ans. 138.1744. 4. What is the solidity of a cylindric ring, whose thickness is 4 inches, and inner diameter 16? Ans. 789.568.

OF

ARTIFICERS' WORK.

ARTIFICERS estimate or compute the value of their works by different measures, viz.*

1. Glazing and Mason's flat work, &c. by the foot. 2. Painting, Plastering, Paving, &c. by the yard. 3. Flooring, Partitioning, Roofing, Tiling, &c. by the square of 100 feet.

4. Brickwork, &c. by the rod of 16 feet, whose square is 2724.

The measures made use of in these works are contained in the following table:

* The best method of taking the dimensions of all sorts of artificers' work is by feet, tenths, and hundredths; because the computation may then be performed by common multiplication, or by the sliding rule, hereafter described.

OF

BRICKLAYERS' WORK.*

BRICKLAYERS Compute or value their work at the rate of › a brick and a half thick, and, if the wall be more or less than this standard, it must be reduced to it as follows:

*Note. In practice it is usual to divide the square feet by 272 only, omitting the ; but the more accurate way is, to divide by 272.25.

The usual way to take the dimensions of a building is to measure half round its middle, on the outside, and half round it on the inside; and this will give the true compass, in which the thickness of the wall is included.

When the height of the building is unequal, take several different altitudes, and their sum, being divided by the number of altitudes you have taken, may be considered as the mean height.

To measure a chimney standing by itself, without any party-wall adjoining; girth it about for the length, and reckon the height of the story for the breadth; but if it stand against a wall, you must measure it round to the wall for the girth, and take the height as before.

When the chimney is wrought upright from the mantel-tree to the ceiling, the thickness must always be the same with the jambs; and nothing is ever deducted for the vacancy between the floor and the mantel-tree, because of the gathering of the breast and wings to make room for the hearth in the next story.

To measure chimney shafts, or that part which appears above the roof; girth them with a line, about the least place for the length, and take the height for the breadth; and if they be four inches thick, set down the thickness at one brickwork; but if they are 9 inches thick, reckon it a brick and a half, in consideration of the plastering and scaffolding.

All windows, doors, &c. are to be deducted out of the contents of the walls in which they are placed. But this deduction is made only with regard to materials; for the value of their workmanship is added to the bill at the stated rate agreed on.

RULE.

Multiply the superficial content of the wall in feet, by the number of half bricks in the thickness, and of that product will be the content required.

Note.-In America, bricklayers' work is generally reckoned by the 1000.

EXAMPLES.

1.* How many square rods are there in a wall 52 feet long, 12 feet 9 inches high, and 2 bricks thick?

There are also other allowances to be made to the workmen, such as those for returns or angles made by two adjoining walls, and double measure for feathered gable-ends, &c.

All ornamental work is generally valued by the foot square, such as arches, doors, architraves, friezes, cornices, &c. But carved mouldings, &c. are often agreed for by the running foot, or lineal

measure.

* In this and the following examples, 272 feet are used for a rod.

By Cross Multiplication.

feet in.
52 6

12 9

630 0

39 4 6

272)669 4 6

2 1244

5

3)12 82 8

4 27 7 as before.

2. How many square rods are there in a wall 62 feet long, 14 feet 8 inches high, and 2 bricks thick?

ro. fe. in. p. Ans. 5 167 9 4

3. If each side wall of a building be 45 feet long on the outside each end wall 15 feet broad on the inside, the height of the building 20 feet, and the gable at each end of the wall 6 feet high, the whole being 2 bricks thick; what is the true content in standard rods?

Ans. 12.2059