NOTE. That 68.06 is one-fourth part of 272.25, and 68 is one-fourth of 272.

In reducing feet into rods, it is usual to reject the odd parts, and divide only by 272, as is done in the second way of the last example; here the answer is 18 rods 3 quarters and 17 feet; about 4 feet more than by the first way, where it is done decimally; a difference too trifling to be considered in practice.

To find proper Divisors for bringing the Answer in feet, or rods, of the Standard thickness; without multiplying the Superficies, by the number of halfbricks, &c.

Divide 3, the number of half-bricks in 14, by the number of half-bricks in the thickness, the quotient will be a divisor, which will give the answer in feet.

But if you would have a divisor to bring the answer in rods at once, multiply 272 by the divisor found for feet, and the product will be a di visor for rods; as in the following table.

xtend the compasses from the tabular divisor against the given thickness, to the length of the wall, that extent will reach from the breadth to the con-tent.

Or by the Carpenters' Rule.

As the tabular divisor, against the thickness of the wall, is to the length of the wall; so is the breadth to the content.

Taking the preceding example, extend the compasses from 74.17 to 72.5, that extent will reach from 19.25 to 18 rods.

The dimensions. of a building are generally taken by measuring half round the outside, and half round the inside, for the whole length of the wall; this length being multiplied by the height gives the superficies. And to reduce it to the standard thickness, &c. proceed as above. All the vacuities, such as doors, windows, window-backs, &c. must be deducted.

To measure an arched-way, arched-window,' or doors, &c. take the height of the window, or door, from the crown or middle of the arch, to the bottom or sill; and likewise from the bottom or still to the spring of the arch, that is, where the arch begins to turn. Then to the latter height add twice the former, and multiply the sum by the width of the window, door, &c. and onethird of the product will be the area, sufficiently near for practice.

2. If a wall be 245 feet 9 inches long, 16 feet 6 inches high, and two bricks and a half thick; how many rods of brick-work are contained therein, when reduced to the standard thickness.

Ans. 24 rods 3 quarters 24 feet.

3. How many rods are contained in a wall 63 feet long, 14 feet 11 inches high, and 2 bricks in thickness, when reduced to the standard P

Ans. 5 rods 218 feet.

4. A triangle gable-end is raised to the height of 15 feet above the end-wall of a house, whose width is 45 feet, and the thickness of the wall is 2 bricks; required the content in rods at standard thickness; Ans. 2 rods 18 feet.

5. Admit the end-wall of a house to be 28 feet 10 inches in breadth, and the height of the roof from the

ground 55 feet 8 inches, the gable (or triangular part above the side walls) to rise 42 courses of bricks, reckoning 4 courses to a foot; and that 20 feet high be 2 bricks thick, 20 feet more 2 bricks thick, and the remaining 15 feet 8 inches 1 brick thick; what will the work come to at 1.5 16s. per rod, the gable being one brick in thickness ? Ans. 1.48 13s. 52d.

III. Of Chimneys.

If you are to measure a chimney standing by itself, without any party-wall being adjoining, then girt it about for the length, and the height of the story is the breadth; the thickness must be the same as the jambs are of, provided that the chimney, be wrought upright from the mantle-tree to the cieling, not deducting any thing for the vacancy between the floor (or hearth) and the mantle-tree, because of the gatherings of the breast and wings, to make room for the hearth in the next story.

If the chimney-back be a party-wall, and the wall be measured by itself, then you must measure the depth of the two jambs, and the length of the breast for a length, and the height of the story for the breadth, at the same thickness your jambs were of.

When you measure chimney-shafts, viz. that part which appears above the roof, girt them with a line round about the least place of them, for the length, and take the height for the breadth and if they be four inches thick, then you must set down their thick ness at one brick-work; but if they be wrought 9 inches thick (as sometimes they are, when they stand high and alone above the roof,) then you must account your thickness 1 brick, in consideration of plastering, and the trouble in scaffolding.

It is customary, in most places, to allow double measure for chimneys..

1. Suppose the figure, ABCDEFGHIK, to be a chimney that hath a double funnel towards the top,and a double shaft, ABC. Then suppose in the parlour, the breast II and the two jambs HI and LK to measure 18 feet 9 inches, and the height of the room HF, or la, to be 12 feet 6 inches ;-in the first floor let the breast and the two jambs, viz. ab, girt 14 feet Sinches, and the height aD, be 9 feet-in the second