Yard (unit)
| Yard | |
|---|---|
| Unit system | imperial/US units |
| Unit of | length |
| Symbol | yd |
| 1 yd in ... | ... is equal to ... |
| imperial/US units |
3 ft 36 in |
| metric (SI) units | 0.9144 m |
The yard (abbreviation: yd) is an English unit of length, in both the British imperial and US customary systems of measurement, that comprises 3 feet or 36 inches. It is by international agreement in 1959 standardized as exactly 0.9144 meters. A metal yardstick originally formed the physical standard from which all other units of length were officially derived in both English systems.
In the 19th and 20th centuries, increasingly powerful microscopes and scientific measurement detected variation in these prototype yards which became significant as technology improved. In 1959, the United States, United Kingdom, Australia, New Zealand, and South Africa agreed to adopt the Canadian compromise value of 0.9144 meters per yard.
The name derives from the Old English gerd, gyrd, &c., which was used for branches, , and measuring rods. It is first attested in the late-7th century laws of Ine of Wessex, where the "yard of land" mentioned is the yardland, an old English unit of tax assessment equal to 1⁄4 hide. Around the same time, the Lindisfarne Gospel's account of the messengers from John the Baptist in the Book of Matthew used it for a branch swayed by the wind. In addition to the yardland, Old and Middle English both used their forms of "yard" to denote the surveying lengths of 15 or 16 1⁄2 ft used in computing acres, a distance now usually known as the "rod".
...
Wikipedia