PROBLEM XVII.

To Transfer a Plan to Another Paper, &c.

AFTER the rough plan is completed, and a fair one is wanted; this may be done by any of the following methods. First Method. Lay the rough plan on the clean paper, keeping them always pressed flat and close together, by weights laid on them. Then with the point of a fine pin or pricker, prick through all the corners of the plan to be copied. Take them asunder, and connect the pricked points on the clean paper, with lines; and it is done. This method is only to be practised in plans of such figures as are small and tolerably regular, or bounded by right lines.

Second Method.-Rub the back of the rough plan over with black-lead powder; and lay this blacked part on the clean paper on which the plan is to be copied, and in the proper position. Then, with the blunt point of some hard substance, as brass, or such-like, trace over the lines of the whole plan; pressing the tracer so much, as that the black lead under the lines may be transferred to the clean paper: after which, take off the rough plan, and trace over the leaden marks with common ink, or with Indian ink.—Or, instead of blacking the rough plan, we may keep constantly a blacked paper to lay between the plans.

Third Method.-Another method of copying plans, is by means of squares. This is performed by dividing both ends and sides of the plan which is to be copied into any conve nient number of equal parts, and connecting the corresponding points of division with lines; which will divide the plan into a number of small squares. Then divide the paper, on which the plan is to be copied, into the same number of squares, each equal to the former when the plan is to be copied of the same size, but greater or less than the others, in the proportion in which the plan is to be increased or diminished, when of a different size. Lastly, copy into the clean squares the parts contained in the corresponding squares of the old plan; and you will have the copy, either of the same size, or greater or less in any proportion.

Fourth Method.-A fourth method is by the instrument called a pentagraph, which also copies the plan in any size required for this purpose, also, Professor Wallace's eidograph may be advantageously employed.

Fifth method.-A very neat method, at least in copying from a fair plan, is this. Procure a copying frame or glass, made in this manner; namely, a large square of the best

window glass, set in a broad frame of wood, which can be raised up to any angle, when the lower side of it rests on a table. Set this frame up to any angle before you, facing a strong light; fix the old plan and clean paper together, with several pins quite around, to keep them together, the clean paper being laid uppermost, and over the face of the plan to be copied. Lay them, with the back of the old plan, on the glass; namely, that part which you intend to begin at to copy first; and by means of the light shining through the papers, you will very distinctly perceive every-line of the plan through the clean paper. In this state then trace all the lines on the paper with a pencil. Having drawn that part which covers the glass, slide another part over the glass, and copy it in the same manner. Then another part and so on, till the whole is copied. Then take them asunder, and trace all the pencil lines over with a fine pen and Indian ink, or with common ink. And thus you may copy the finest plan, without injuring it in the least.

OF ARTIFICERS' WORKS,

AND

TIMBER MEASURING.

1. OF THE CARPENTER'S OR SLIDING RULE.

THE Carpenter's or Sliding Rule, is an instrument much used in measuring of timber and artificers' works, both for taking the dimensions, and computing the contents.

The instrument consists of two equal pieces, each a foot in length, which are connected together by a folding joint.

One side or face of the rule is divided into inches, and eighths, or half-quarters. On the same face also are several plane scales divided into twelfth parts by diagonal lines; which are used in planning dimensions that are taken in feet and inches. The edge of the rule is commonly divided decimally, or into tenths; namely, each foot into ten equal

parts, and each of these into ten parts again; so that by means of this last scale, dimensions are taken in feet, tenths, and hundredths, and multiplied as common decimal numbers, which is the best way.

On the one part of the other face are four lines, marked A, B, C, D; the two middle ones в and c being on a slider, which runs in a groove made in the stock. The same num. bers serve for both these two middle lines, the one being above the numbers, and the other below.

These four lines are logarithmic ones, and the three a, b, c, which are all equal to one another, are double lines, as they proceed twice over from 1 to 10. The other or lowest line, D, is a single one, proceeding from 4 to 40. It is also called the girt line, from its use in computing the contents of trees and timber; and on it are marked we at 17.15, and AG at 18-95, the wine and ale gage points, to make this instrument serve the purpose of a gaging rule.

On the other part of this face, there is a table of the value of a load, or 50 cubic feet of timber, at all prices, from 6 pence to 2 shillings a foot.

When 1 at the beginning of any line is accounted 1, then the 1 in the middle will be 10, and the 10 at the end 100; but when 1 at the beginning is counted 10, then the 1 in the middle is 100, and the 10 at the end 1000; and so on. And all the smaller divisions are altered proportionally.

II. ARTIFICERS' WORK.

ARTIFICERS Compute the contents of their works by several different measures. As,

Glazing and masonry, by the foot; Painting, plastering, paving, &c. by the yard, of 9 square feet: Flooring, partitioning, roofing, tiling, &c. by the square of 100 square feet:

And brickwork, either by the yard of 9 square feet, or by the perch, or square rod or pole, containing 2721 square feet, or 30 square yards, being the square of the rod or pole of 16 feet or 5 yards long.

As this number 272 is troublesome to divide by, the is often omitted in practice, and the content in feet divided only by the 272.

All works, whether superficial or solid, are computed by the rules proper to the figure of them, whether it be a triangle, or rectangle, a parallelopiped, or any other figure.

III. BRICKLAYERS' WORK.

BRICKWORK is estimated at the rate of a brick and a half thick. So that if a wall be more or less than this standard thickness, it must be reduced to it, as follows:

Multiply the superficial content of the wall by the number of half bricks in the thickness, and divide the product by 3. The dimensions of a building may be taken by measuring half round on the outside and half round on the inside; the sum of these two gives the compass of the wall, to be multiplied by the height, for the content of the materials.

Chimneys are commonly measured as if they were solid, deducting only the vacuity from the hearth to the mantle, on account of the trouble of them. All windows, doors, &c. are to be deducted out of the contents of the walls in which they are placed.

The dimensions of a common bare brick are, 81⁄2 inches long, 4 inches broad, and 24 thick; but including the half inch joint of mortar, when laid in brickwork, every dimen. sion is to be counted half an inch more, making its length 9 inches, its breadth 44, and thickness 3 inches. So that every 4 courses of proper brickwork measures just 1 foot or 12 inches in height.

EXAMPLES.

EXAM. 1. How many yards and rods of standard brick. work are in a wall whose length or compass is 57 feet 3 inches, and height 24 feet 6 inches; the wall being 24 bricks or 5 half bricks thick? Ans. 8 rods, 17 yards.

EXAM. 2. Required the content of long, and 14 feet 8 inches high, and 2

a wall 62 feet 6 inches bricks thick?

Ans. 169-753 yards.

EXAM. 3. A triangular gable is raised 17 feet high, on an end wall whose length is 24 feet 9 inches, the thickness being 2 bricks required the reduced content?

Ans. 32-08 yards.

EXAM. 4. The end wall of a house is 28 feet 10 inches long, and 55 feet 8 inches high, to the eaves; 20 feet high is 2 bricks thick, other 20 feet high is 2 bricks thick, and the remaining 15 feet 8 inches is 1 brick thick; above which is a triangular gable, of 1 brick thick, which rises 42 courses of bricks, of which every 4 courses make a foot. What is the whole content in standard measure?

Ans. 253-626 yards.

IV. MASONS' WORK.

To Masonry belong all sorts of stone work; and the measure made use of is a foot, either superficial or solid.

Walls, columns, blocks of stone or marble, &c. are mea sured by the cubic foot; and pavements, slabs, chimney. pieces, &c. by the superficial or square foot.

Cubic or solid measure is used for the materials, and square measure for the workmanship.

In the solid measure, the true length, breadth, and thick. ness are taken and multiplied continually together. In the superficial, there must be taken the length and breadth of every part of the projection which is seen without the general upright face of the building.

EXAMPLES.

EXAM. 1. REQUIRED the solid content of a wall, 53 feet 6 inches long, 12 feet 3 inches high, and 2 feet thick?

Ans. 13103 feet. EXAM. 2. What is the solid content of a wall, the length being 24 feet 3 inches, height 10 feet 9 inches, and 2 feet thick? Ans. 521-375 feet.

EXAM. 3. Required the value of a marble slab, at 8s. per foot; the length being 5 feet 7 inches, and breadth 1 foot 10 inches ? Ans. 41. 1s. 10d.

EXAM. 4. In a chimney-piece, suppose the

length of the mantle and slab, each 4 feet 6 inches

breadth of both together

To this branch belongs all the wood-work of a house, such as flooring, partitioning, roofing, &c.

Large and plain articles are usually measured by the square foot or yard, &c. ; but enriched mouldings, and some other articles, are often estimated by running or lineal measure; and some things are rated by the piece.

In measuring of Joists, take the dimensions of one joist,