A unit of measurement is simply an arbitrarylength, area, or volume, generally adopted andagreed upon as a standard unit of measurement.The basic standard for linear measurement, forexample, is the meter, and the actual length ofa meter is, in the last analysis, equal to the lengthof a bar of metal called the International MeterBar, one replica of which is kept in the NationalBureau of Standards, Washington, D.C.As an EA, you will not necessarily beworking with all the units described in thischapter, and therefore need not attempt tomemorize them all. Many are included simply toshow that units are arbitrary and that there aremany different kinds of units in use.UNITS OF LINEAR MEASUREMENTLinear measure is used to express distancesand to indicate the differences in their elevations.The standard units of linear measure are the footand the meter. In surveying operations, both ofthese standard units are frequently dividedinto tenths, hundredths, and thousandths formeasurements.When longer distances areinvolved, the foot is expanded into a statute orto a nautical mile and the meter into a kilometer.Table 1-1 shows the conversion factors for thecommon linear measurements.English UnitsIn the English system, the most commonlyused basic unit of linear measurement is the foot,a unit that amounts to slightly more than three-tenths of the international meter. In what iscalled ENGINEER’S measurement, the foot issubdivided decimally; that is, into tenths,hundredths, or thousandths of a foot. In what iscalled CARPENTER’S measurement, or Englishunits, the foot is subdivided into twelfths calledinches, and the inch is further subdivided intoeven-denominator fractional parts, as 1/2 in., 1/4in., 1/8 in., and so on.Fractions or multiples of the basic 1-ft unitare used to form larger units of linear measureas follows:of Spanish and Portuguese origin, was formerlyused to measure land boundaries in those areasof the United States that were at one time underSpanish control. In those areas old deeds andother land instruments still contain propertydescriptions in varas, which vary from state tostate and country to country from 32 to 43 in.Metric UnitsIn many of the non-English-speaking countriesof the world, the most commonly used basic unit1-27Table 1-1.-Linear Conversion FactorsA unit of linear measurement, called a VARA
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