Summer Issue 2021 - 85

The Articles of Confederation declared
the acre the standard unit of land
measurement, and the Northwest
Ordinances of 1785 and 1787 divided
land beyond the original 13 states into
six-square-mile gridded townships.
equal 160,000 square links, divided
by 100,000, you know you have 1.6
acres, 264 by 264 feet-precisely
the size of the Vancouver/Portland
blocks with rights-of-way. Fortuitously,
thanks to Gunter's numbers4-and-10-based
chain, 400 links
equal 80.45 meters-only one-half
percentage point different from an
80-meter mediation.
Since 80 chains equal one mile,
block city (Vancouver, Washington)
consisting of 200-by-200-foot
blocks, rather than the three-chain
(198-foot) New York module. Portland's
first plat followed on 16
blocks in 1845.
Created in 1623, English mathematician Edmund Gunter's surveying chain
of 100 links contains the seeds for mediating the number 4-based imperial
system with the number 10-based decimal metric comparables. Defining an
acre as one-by-10 chains meant that it was also 100 by 1,000 links, or 100,000
square links. Five Gunter links (7.92 in) equaled 39.6 inches, less than a quarter
inch different than the current 39.37-inch meter.
into major roads. Identification
of land ownership by township,
range, and section became standard
American practice.
However, block and lot lines
tended to gravitate toward the
decimal scale of 100-foot multiples
rather than chains. The New York
plan of 1811 divided cross-block
widths into three chains (66 x 3
= 198 feet) but were commonly
referred to as 200 feet, while New
York block lengths varied from 405
to 920 feet, depending upon distances
to the Hudson River and the
East River. In 1844 on a 640-acre,
one-square-mile township section,
Henry Williamson platted a 400Mediating
Metric and
Imperial Systems
Gunter's chain of 100 links actually
contains the seeds for mediating
the number 4-based imperial
system with the number 10-based
decimal metric comparables.
Defining an acre as one-by-10
chains meant that it was also
100 by 1,000 links, or 100,000
square links. Gunter numbered his
links so that one could measure
any rectangular area by calculating
its length times its width in
links. Dividing that product by
a 100,000-square-links-per-acre
divisor yielded its acreage simply
by moving the decimal point five
digits to the left. A 10-by-10-chain
parcel meant 1,000 by 1,000 links,
to equal 1 million square links,
divided by the 100,000-divisor,
yielding 10 acres.
For different dimensions, if you
measured 400 by 400 links to
at 100 links per chain that is 8,000
links, or 5,280 feet, or 1,600 meters
at five links per meter. If in 1623,
almost two centuries before the
metric system was adopted in revolutionary
France in 1795, Gunter had
simply described his system's basic
units as links, deka-links, and hecto-links,
that decimal system could
likely have preempted later decimal
metric measures. As it is now,
8,000 links equals 1,609 meters
rather than a simpler 1,600.
The Case for a Metric Acre
Conversion between the imperial
and metric systems is not intuitive
and requires laborious, inefficient
conversion of every measurement.
Rapid switching from imperial to
metric could be confusing, disruptive,
and prone to error. Rather than
convert acres to square meters or
hectares, one should slightly shift
the imperial acre to a more usable
" metric acre " form that is easier
to envision, calculate, and subdivide.
And there is a way to shift to
accurate metric measurement that
mediates the transition in an analogous
way that the metric ton (1,000
kg equals 2,204 lbs) has been
accepted for weight, even though it
is 10 percent different from the customary
ton (2,000 lbs).
The purpose of measuring the
long acre in the 17th century as a
chain by a furlong was to facilitate
SUMMER 20 21
URBAN LAND
85
SMITHSONIAN
US DEPT OF INTERIOR
Summer Issue 2021

Table of Contents for the Digital Edition of Summer Issue 2021
