On the face of it, the dimensions make no sense: Each link is a fraction under 8 inches long; 10 links make slightly less than 6 feet, 8 inches and a full length of 66 feet. In fact, he had made a brilliant synthesis of two incompatible systems, the traditional English land measurements, based on the number 4, and the newly introduced system of decimals based on the number An acre measured 4, square yards in traditional units and 10 square chains in Gunter's system.
Thus, if need be, the entire process of land measurement could be computed in decimalized chains and links, and then converted to acres by dividing the results by Illustrations are available online. The method of surveying a field or other parcel of land was to determine corners and other significant locations, and then to measure the distance between them, taking two points at a time.
The surveyor is assisted by a chainman. A ranging rod usually a prominently coloured wooden pole is placed in the ground at the destination point. Starting at the originating point the chain is laid out towards the ranging rod, and the surveyor then directs the chainman to make the chain perfectly straight and pointing directly at the ranging rod.
Another ranging rod is put in the ground at the forward end of the chain, and the chain is moved forward so that its hind end is at that point, and the chain is extended again towards the destination point. The longest chain line passing through the center of the survey area is known as. The maximum tolerances in overall length of a 20 m and 30 m metric chains should be respectively.
The ruling principle of plane surveying is to work from:. What is the main objective of providing tie line in chain survey?
Which of the following chains was originally used for land measurement with a length of 66 ft? A 30 m chain used for a survey was found to be What is true area of the field? Surveyor's Chain. Usage conditions apply. International Media Interoperability Framework.
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View manifest View in Mirador. Description In an English mathematician and astronomer named Edmund Gunter described a surveyor's chain with links, measuring 66 feet 22 yards or 4 poles overall. By this design, one square chain equals square yards, ten square chains equal an acre, and eighty chains equal a mile. The brass tellers are sometimes designed to be inserted in the length of the chain, but though less liable to catch in hedges, etc. The ends of the chain are furnished with brass handles attached by means of swivel joints, and the length of links is measured from the outside of one handle to the outside of the other.
It is 66 ft. The Engineer's chain is ft. It is heavier than the Gunter's chain, but being longer does not need to be laid down so frequently in the measurement of a definite distance; for this reason there is less liability to error from the inaccurate marking of the ends of the chain.
Again, as the levelling staff is usually graduated in feet and decimal parts of a foot, this chain is more convenient than the 66 ft. In municipal work, too, the ft.
Metre chains are also in use, the commonest lengths being 10, 20, and 25 metres. They are subdivided into one-fifth parts of a metre and tallied at every two metres from each end. Norman Thomas. London: Edward Arnold, There is another measure, unknown to the law, which has set the commissioners at defiance, by the universality of its use.
It has gained its footing by the conveniences which it offers, and those conveniences are a consequence of its connexion with decimal division. We refer to the chain, Gunter's chain, as it is called, used in measurement of land. It is 22 yards, the tenth part of a furlong, in length; and, as the commissioners justly remark, is, in theory, the greatest anomaly in our system. But ten square chains make an acre, and the chain is divided into one hundred links, which makes the use of it so easy, that a surveyor would look upon any attempt to alter it as an infringement of the fundamental compact.
All measurements of land, and all the multifarious arrangements arising out of them, have been based upon this land chain, which is therefore unalterable. On this there is but one opinion, whether of witnesses or commissioners.
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