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Fourthly, Common Brick-work is meafur'd by the Square Rod, containing 272 Square Feet But if the Wall be not one Brick and half thick, it must be reduced to that Standard, by this General Rule. Multiply the Superficial Content of the Wall by the thickness thereof in half Bricks, divide that product by 3, and it gives the true Quantity:
If a Brick Wall that is 1 Brick thick be 40 Feet long, and 9 Feet II Inches high from the Foundation, it will contain 1 Rod Qu. 56 Feet.
If a Brick Wall 2 Bricks thick be so Feet 6 Inches in length, and 14 Feet 9 Inches in breadth; the true content after it is reduced to the Standard, viz. 14 Brick, is 3 Rod, 2 Quarters, 40 Feet.
700 : 0
Numb. Bricks 4: 0
3)29 79: 4 (993
Which divided by 70, 2727, gives 3 Rods 176 Feet: Which is the true Content of the Wall.
N. B. The Bricklayers have a particular way of measuring Chimneys: Which is by multiplying the Girt of the Chimney, by the heighth thereof, from the Foundati on to the Hearth of the next Chimney; and the thickness of the Jams is taken for its thickness which method they follow, till they come to the Shafts.
And thofe they girt for the length of a Wall, the heighth of which is the heighth of the Shafts, and the thickness always two
If a Chimney be 24 Feet 3 Inches about, its Heighth 9 Feet 5 Inches, and the thicknefs of the Jams one Brick and half. what will be its Content? Anfo Rod 3 Qu. 24 Feet.
24 X 35
228 4. Anf. in Feet
Note, Thus they measure the Chimneys of every Floor till they come to the Shafts.
If the Girt of the Chimney Shafts be 20 Feet and the heighth 12 Feet 3 Inches, how much is their Content? Anfo Rod 3 Qu. 41 Feet.
The measuring Book ought to be divid ed into three Columns (as the Example fbews) in the firft, the Names of the Dimenfions are fet down, in the fecond, the Dimenfions themselves, and in the laft the product of thofe Dimenfions.
After you have taken, and fet down the Dimenfions: Your next work is to multiply them upon a wafte Paper, and fet down their products over against them in the fecond Column: As you may fee in the Example.