- Knotted cord
Knotted cords were a primitive surveyor's tool for measuring distances. It is literally a length of cord with knots at regular intervals. They were eventually replaced by surveyor's chains, 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 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 layout a
right angle 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 s, royal surveyors who measured out the sides of fields (Egyptian "3ht"). The knotted cords (Egyptian "ht") were 100 royalcubit 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.External links
* [http://plsurvey.com/surveyinghistory.html Egyptian rope stretchers using knotted cord for survey]
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