Civil Engineering Reference
In-Depth Information
in decimal form rather than minutes and seconds. Most calculators
can carry the degree out to 6 places after the decimal point
The Metric System
The base, or fundamental, unit in the metric system is the
meter
.
The meter is defined as the distance between two scribed marks on
a standard bar made of platinum-iridium kept in the vaults of the
International Bureau of Weights and Measures, near Paris, France.
Of course, many other standard meter bars have been made from
the measurement on this bar. It is permissible and official to use this
measurement in the United States, and, in fact, the yard, the basis
for the English system of measurement, has been defined as exactly
3600
39.37 inches.
The advantage (and immeasurably greater convenience) of the
metric system over the English system of units lies in the fact that
it is expressed in tenths, thereby readily allowing the use of deci-
mals. However, the American public is accustomed to the English
units, and as recent experience indicates, the system should continue
for a long time. The metric system is, of course, in common use all
over the world with the exception of some English-speaking coun-
tries. The meter is used like the yard to measure cloth and short
distances.
Units of other denominations are named by prefixing to the word
meter the Latin numerals for the lower denominations and the
Greek numerals for the higher denominations, as shown in Table
5-16.
/
3937
meter, or 1 meter
=
Table 5-16
Denominations
Lower Denomination
Higher Denomination
Greek
Equivalent
Greek
Equivalent
Deci
1
/
10
Deka
10
1
/
100
Centi
Hecto
100
Milli
1
/
1000
Kilo
1000
Micro
1
/
1
,
000
,
000
Myria
10,000
Mega
1,000,000
Therefore, 1 decimeter
=
1
/
10
of a meter, 1 millimeter
=
1
/
1000
of a meter, 1 kilometer
1000 meters, and so forth. From this
explanation of the metric prefixes, the linear equivalents shown in
Table 5-17 can easily be understood.
=
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