of linear measure is the meter. The length of a
meter was originally designed to equal (and does
equal very nearly) one ten-millionth part of the
distance, measured along a meridian, between the
earth’s equator and one of the poles. A meter
equals slightly more than 1.09 yd.
The big advantage of the metric system is the
fact that it is a decimal system throughout; that
is, the fact that the basic unit can be both
subdivided into smaller units decimally and
converted to larger units decimally by simply
moving the decimal point in the appropriate
direction. Names of units smaller than the meter
are indicated by the Latin prefixes deci-
(one-tenth), centi- (one-hundredth), mini- (one-
thousandth), and micro- (one-millionth), as
follows:
Names of units larger than the meter
are indicated by the Greek prefixes deca- (ten),
hecto- (one hundred), kilo- (one thousand), myria-
(ten thousand), and mega- (one million), as
follows:
UNITS OF AREA MEASUREMENT
In the English and metric system, area is most
frequently designated in units that consist of
squares of linear units, as square inches, feet,
yards, or miles; or square centimeters, meters, or
kilometers. In the English system, the land-area
measurements most commonly used are the
square foot and the acre. Formerly the square rod
(1 rod = 16.5 ft) and the square Gunter’s
chain ( 1 Gunters’s chain = 66 ft) were used. One
of the area measurements, with its equivalents,
is as follows:
An equilateral rectangular (square) acre
measures 208.71 ft on a side. There are 640 acres
in a square mile.
Other area equivalents that may be of value
to you are as follows:
Actually, more attention should be given to
linear equivalents. If you know the linear
conversion factor from one unit to the other, you
can always compute for any equivalent area or
even volume. Just remember, area is expressed in
square units and volume is expressed in cubic
units.
Example: Find the area of a rectangle 2 ft by
3 ft in square inches.
Area = 2 ft x 3 ft = (2 x12)(3 x 12) = 864 sq in.
UNIT OF VOLUME MEASUREMENT
From your study of mathematics, you learned
that volume is the measure of the amount of space
that matter occupies. It is expressed in certain
cubic units, depending upon the linear
measurements or dimensions of the object.
As an EA, you will find that your interest in
unit volume of measurements will be from the
standpoint of earthwork, construction materials,
material testing, rainfall runoff, and capacities of
structures, such as, for example, a reservoir. The
accuracy of your computations will depend upon
your knowledge of the correct conversion factors
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