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Containing Decimal Fractions, the Square Root,
Geometrical Definitions, Theorems and Problems; with the nature and use of the Tables of Logarithm Numbers, Sines, Tangents, and Secants.
URVEYING is that art which enables us to
give a plan or just representation of any piece or parcel of land, and to determine the content thereof in such measure as is agreeable and customary to the country or place u here the land is.
This science depends on some parts of the mathematics, which must be known before we can treat of it, wherefore we shall begin with
If we suppose unity or any one thing to be divided into any assigned number of equal parts, this number is called the denominator; and if we chuse to take any number of such parts less than the whole, this is called the numerator of a fraction.
The numerator in the vulgar form, is always wrote over the denominator, and these are separated by a small line thus is or To Nererate or the first of these is called 5 twelfths, and the latter 7 twelfths of an inch, yard, perch, 8c. or of whatever the whole thing originally was.
Fractions are expressed in two forms, that is, either vulgarly or decimally.
All fractions whose denominators do not consist of a cypher or cyphers set after unity, are called vulgar ones, and their denominators are always wrote under their numerators. The treating of these would be foreign to our present purpose. But fractions, whose denominators consist of an unit prefixed to one or more cyphers, are called decimal fractions; the numerators of which are written without their denominators, and are distinguished from integers by a point prefixed : thus x 10 % and to an in the decimal form are expressed by .2 .42 .172
The denominators of such fractions always consisting of an unit, prefixed to as many cyphers as there are places of figures in the numerators, it follows, that any number of cyphers put after those numerators will neither increase nor lessen their value: for % % and 90% are all of the same value, and will stand in the decimal form thus .3 .30.300; but a cypher or c ners prefixed to those numerators lessen their value in a tenfold proportion: for 6 10% and
which in the decimal form we denote by.3.03 and .003, are fractions, of which the first is ten times greater than the second ; and the second, ten times greater than the third.
Hence it appears, that as the value and denomination of any figure or number of figures in common
arithmetic is enlarged, and becomes ten or an hundred, or a thousand times greater, by placing one or two, or three cyphers after it ; so in decimal arithmetic, the value of any figure or number of figures, decreases, and becomes ten, or a hundred, or a thousand times less, while the denomination of it increases, and becomes so many times greater, by prefixing one, or two, or three cyphers to it: and that any number of cyphers, before an integer, or after a decimal fraction, has no effect in changing their values. Integers.
1 6 3
Hund. of thous.
Addition of DECIMALS. Having placed those figures which are equi-distant from the point, (as well integers as fractions) under each other, add them as if they were integers.
Add 4.7832 3.2543 7.8251 6.03 2.857 and 3.251 together. Place them thus.
4.7832 3.2543 7.8251 6.03 2.857 3.251
Add 6.2 121.306 .75 2.7 and .0007 toge121.306
.75 2.7 .0007
What's the sum of 6.57 1.026 .75 146.5 8.7 526. 5.97 and .0271 ?
What's the sum of 4.51 146.071.507 .0006 132. 62.71 .507 7.9 and .10712 ?
Subtraction of DECIMALS. Having placed the figures which are equi-distant from the point under each other; deduct as if they were integers.
From 38.765 take 25.3741
From 2.4 take .8472
From 71.45 take 8.4897248