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Units of Measurement.
Manual of Instructions for the Survey of the Public Lands of the United States
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p. 18
Chapter II
Methods of Survey
The methods described in this chapter comprise the specifications
for determining the length and direction of lines.
DISTANCE MEASUREMENT
Units
2-1. The law prescribes the chain as the unit of linear measure for the survey
of the public lands. All returns of measurements in the rectangular system are
made in the true horizontal distance in miles, chains, and links. (Exceptions
are special requirements for measurement in feet in townsite surveys, chapter
VII, and mineral surveys, chapter X.)
Units of Linear Measure |
1 chain | = | 100 links |
| | = | 66 feet |
1 mile | = | 80 chains |
| = | 5,280 feet |
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Units of Area |
1 acre | = | 10 square chains |
| = | 43,560 square feet |
1 square mile | = | 640 acres |
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The chain unit, devised in the seventeenth century by Edmund Gunter, an English
astronomer, is so designed that 10 square chains are equivalent to one acre.
In the English colonial area of the United States the boundaries of land were
usually measured in the chain unit, but lengths of lines were frequently expressed
in poles. One pole is equal to 25 links, and four poles equal one chain. The
field notes of some early rectangular surveys in the southern States show the
distance in "perches," equivalent to poles. The term now commonly
used for the same distance is the rod.
Land grants by the French crown were made in arpents. The arpent is a unit
of area, but the side of a square arpent came to be used for linear description.
The Spanish crown and the Mexican Government granted lands which were usually
described in linear varas. Both the arpent and the vara have slightly different
values in different States. The conversions most often needed are shown in the
Standard Field Tables.
| (The information below NOT taken
from The Manual of Instructions for the Survey of the Public
Lands.)
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Surveying Measurements
- 1 yard = 3 ft = 0.9144 meter
- 1 rod, perch, or pole = 25 links = 16.5 ft
- 4 rods = 1 chain
- 1 chain = 4 rods = 66 ft = 100 links
- 10 chains = 1 furlong
- 1 link = 1/100 of surveyor's chain = 7.92 inches
- 25 links = 1 rod = 16.5 ft
- 100 links = 1 chain = 66 ft
- 1 furlong = 10 chains = 1/8 mile = 220 yards = 660 ft =
201.168 meters
- 8 furlongs = 1 mile
- 1 mile = 80 chains = 320 rods = 1,760 yards = 5,280 ft
= 1,609.344 meters
- league = 3 statute miles = 4,828.032 meters
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