Knotted cord
Encyclopedia
A knotted cord was a primitive surveyor
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

's tool for measuring distances. It is literally a length of cord with knots at regular intervals. They were eventually replaced by surveyor's chain
Chain (unit)
A chain is a unit of length; it measures 66 feet or 22 yards or 100 links . There are 10 chains in a furlong, and 80 chains in one statute mile. An acre is the area of 10 square chains...

s, which being made of metal were less prone to stretching and thus were more accurate and consistent.

Knotted cords were used by many ancient cultures. The Greek schoenus is referred to as a rope used to measure land. Ropes generally became cables and chains with Pythagoras
Pythagoras
Pythagoras of Samos was an Ionian Greek philosopher, mathematician, and founder of the religious movement called Pythagoreanism. Most of the information about Pythagoras was written down centuries after he lived, so very little reliable information is known about him...

 making the Greek agros a chain of 10 stadia equal to a nautical mile c 540 BC. The Romans used a waxed cord for measuring distances.

An interesting form of a knotted cord is one 12 lengths long (the units do not matter) which is closed into a loop. This cord can be used to lay out a right angle
Right angle
In geometry and trigonometry, a right angle is an angle that bisects the angle formed by two halves of a straight line. More precisely, if a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles...

 by forming the loop of cord into a 3–4–5 triangle. This could be used for laying out the corner of a field or a building foundation, for instance.

Ancient Egypt

Knotted cords were used by rope stretcher
Rope stretcher
In ancient Egypt rope stretchers were surveyors who measured property demarcations and foundations using knotted cords which they stretched in order to take the sag out of the rope. When performed by kings during the initial stage of temple building the Stretching of the Rope was probably a...

s, royal surveyors who measure
Measurement
Measurement is the process or the result of determining the ratio of a physical quantity, such as a length, time, temperature etc., to a unit of measurement, such as the metre, second or degree Celsius...

d out the sides of fields (Egyptian
Egyptian language
Egyptian is the oldest known indigenous language of Egypt and a branch of the Afroasiatic language family. Written records of the Egyptian language have been dated from about 3400 BC, making it one of the oldest recorded languages known. Egyptian was spoken until the late 17th century AD in the...

 3ht). The knotted cords (Egyptian ht) were 100 royal cubit
Cubit
The cubit is a traditional unit of length, based on the length of the forearm. Cubits of various lengths were employed in many parts of the world in Antiquity, in the Middle Ages and into Early Modern Times....

s in length with a knot every hayt or 10 royal cubits. The rope stretchers stretched the rope in order to take the sag out it and keep the measures uniform.

Since land in Egypt was measured in several different units there would have been knotted cords with the knots spaced in each unit including mh t3 or land cubits, remen royal cubits, rods or ha3t, generally the lengths in multiples of 100 units. The longest measured length listed in the Rhind papyrus is a circumference of about a Roman mile with a diameter of 9 khet.

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