Rods and Links

Date: 03/28/2002 at 01:09:25
From: Marybeth Johnson
Subject: Rods and links

I need to know how many rods and links there are in a foot.

Date: 03/28/2002 at 07:57:36
From: Doctor Sarah
Subject: Re: Rods and links

Hi Marybeth - thanks for writing to Dr. Math.

From Russ Rowlett's _How Many? A Dictionary of Units of Measurement_:

   http://www.unc.edu/~rowlett/units/   

rod (rd) 
a traditional unit of distance equal to 5.5 yards (16 feet 6 inches or 
exactly 5.0292 meters). The rod and the furlong were the basic 
distance units used by the Anglo-Saxon residents of England before the 
Norman conquest of 1066. The Saxons generally called this unit the 
gyrd, a word which comes down to us as the name of a different unit, 
the yard. "Rod" is another Saxon word which meant just what it means 
today: a straight stick. The Normans preferred to call the gyrd a pole 
or a perch (a word of French origin, meaning a pole; see perche). The 
length of the rod was well established at about 5 meters at least as 
early as the eighth century. Scholars are not sure how it was related 
to shorter units. It may have been considered equal to 20 "natural" 
feet (actual foot lengths; see foot), or it may have been measured "by 
hand" as 30 shaftments. In any case, when the modern foot became 
established in the twelfth century, the royal government did not want 
to change the length of the rod, since that length was the basis of 
land measurement, land records, and taxes. Therefore the rod was 
redefined to equal 16.5 of the new feet. This length was called the 
"king's perch" at least as early as the time of King Richard the 
Lionheart (1198). Although rods and perches of other lengths were used 
locally in Britain, the king's perch eventually prevailed. The 
relationship between the rod and the other English distance units was 
confirmed again by the Parliamentary statute of 1592, which defined 
the statute mile to be either 320 rods or 1760 yards, thus forcing the 
rod to equal exactly 5.5 yards or 16.5 feet.

link
a traditional unit of distance used by surveyors, equal to 0.01 chain. 
In Britain, one link is exactly 0.66 feet, or 7.92 inches, or 
approximately 20.12 centimeters. In the U.S., both 66-foot and 
100-foot chains have been used; for a 100-foot chain the link is the 
same as the foot.

- Doctor Sarah, The Math Forum
  http://mathforum.org/dr.math/