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The English chain is divided into 100 links, each link being. 7.92 inches. And 80 chain-lengths is 1 English mile.

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The Scots chain is divided in 100 links, each link being 8.88 inches, and 80 chains is one Scots mile.

To measure furfaces and folids by duodecimals, or cross multiplication.

RULE.

Multiply each denomination of the length by the feet of breadth, beginning at the lower place, and setting each product under that denomination of the multiplicand from which it arises, carrying by 12, when neceffary, to the higher place. Then multiply by the inches of breadth (if any) setting each product one place to the right hand, carrying by 12 as above. Laftly, Multiply by the parts, fetting down each product, another place to the right, and fo on.

EXAMPLE.

A pavement 16 feet 4 inches long, 7 feet 6 inches broad, How many fquare feet?

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First, fay, 7 times 4 is 28, which is 2 to carry, and 4 over. Write down 4, the excefs in the column of inches; then fay, 7 times 16 is 112, and the 2 you carry is 114, which set down in the column of feet. Again, 6 times 4 is 24, which is 2 to carry and o over; then fay, 6 times 16 is 96, and 2 is 98, which is 8 feet 2 inches; which, when you'll have placed in their proper columns, add, and the fum will be 122 feet 6 inches.

Nott, The fuperficial content of masons, joiners, plasterers, painters, &c. work, is frequently caft up by the preceding rule; for the better understanding of which obferve, that

The fuperficies of any rectangle is found by multiplying the length by the breadth; and the content of any triangle is found by multiplying half the base by the perpendicular altitude, as fhall be explained afterwards.

Any lineal measure, multiplied by the fame lineal measure, produces fquares of the fame. Thus, lineal feet, multiplied by lineal feet, produce square feet; lineal inches into lineal inches produce fquare inches, and so on.

Lineal feet into lineal-inches. produce rectangles I foot long, and 1 inch broad, which, divided by 12 quats feet; and the remainder multiplied by 12, produces fquare inches,

Lineal feet into lineal lines produce rectangles I foot long and 1 line broad; which, divided by 144 quots fquare feet, and each unit in the remainder are rectangles, equal to fquare inches.

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PROBLEM I. Plate 5. fig. 70.

To find the area of a fquare.

RULE.

Multiply the fide by itself, and the product will be the area.

EXAMPLE I.

How many fquare yards are in a fquare, whofe fide is 15 feet?

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