A measuring rod is a tool used to physically measure lengths and survey areas of various sizes. Most measuring rods are round or square sectioned; however, they can also be flat boards. Some have markings at regular intervals. It is likely that the measuring rod was used before the line, chain or steel tapes used in modern measurement. [1]
The oldest preserved measuring rod is a copper-alloy bar which was found by the German Assyriologist Eckhard Unger while excavating at Nippur (pictured below). The bar dates from c. 2650 BC. and Unger claimed it was used as a measurement standard. This irregularly formed and irregularly marked graduated rule supposedly defined the Sumerian cubit as about 518.5 mm (20.4 in), although this does not agree with other evidence from the statues of Gudea from the same region, five centuries later. [2]
Rulers made from ivory were in use by the Indus Valley Civilization in what today is Pakistan, and in some parts of Western India prior to 1500 BCE. Excavations at Lothal dating to 2400 BCE have yielded one such ruler calibrated to about 1⁄16 inch (1.6 mm) [3] Ian Whitelaw (2007) holds that 'The Mohenjo-Daro ruler is divided into units corresponding to 1.32 inches (34 mm) and these are marked out in decimal subdivisions with remarkable accuracy—to within 0.005 inches (0.13 mm). Ancient bricks found throughout the region have dimensions that correspond to these units.' [4] The sum total of ten graduations from Lothal is approximate to the angula in the Arthashastra. [5]
Measuring rods for different purposes and sizes (construction, tailoring and land survey) have been found from China and elsewhere dating to the early 2nd millennium B.C.E. [6]
Cubit-rods of wood or stone were used in Ancient Egypt. Fourteen of these were described and compared by Lepsius in 1865. [7] Flinders Petrie reported on a rod that shows a length of 520.5 mm, a few millimetres less than the Egyptian cubit. [8] A slate measuring rod was also found, divided into fractions of a Royal Cubit and dating to the time of Akhenaten. [9]
Further cubit rods have been found in the tombs of officials. Two examples are known from the tomb of Maya—the treasurer of the 18th dynasty pharaoh Tutankhamun—in Saqqara. Another was found in the tomb of Kha (TT8) in Thebes. These cubits are ca 52.5 cm (20.7 in) long and are divided into seven palms, each palm is divided into four fingers and the fingers are further subdivided. [10] Another wooden cubit rod was found in Theban tomb TT40 (Huy) bearing the throne name of Tutankhamun (Nebkheperure). [11]
Egyptian measuring rods also had marks for the Remen measurement of approximately 370 mm (15 in), used in construction of the Pyramids. [12] [13]
An oak rod from the Iron Age fortified settlement at Borre Fen in Denmark measured 53.15 inches (135.0 cm), with marks dividing it up into eight parts of 6.64 inches (16.9 cm), corresponding quite closely to half a Doric Pous (a Greek foot). [14] A hazel measuring rod recovered from a Bronze Age burial mound in Borum Eshøj, East Jutland by P. V. Glob in 1875 measured 30.9 inches (78 cm) corresponding remarkably well to the traditional Danish foot. [15] The megalithic structures of Great Britain has been hypothesized to have been built by a "Megalithic Yard", though some authorities believe these structures have been measured out by pacing. [16] [17] [18] Several tentative Bronze Age bone fragments have been suggested as being parts of a measuring rod for this hypothetical measurement. [16]
Large public works and imperial expansion, particularly the large network of Roman roads and the many milecastles, made the measuring rod an indispensable part of both the military and civilian aspects of Roman life. Republican Rome used several measures, including the various Greek feet measurements and the Oscan foot of 23.7 cm. [19] Standardisation was introduced by Agrippa in 29 BC, replacing all previous measurements by a Roman foot of 29.6 cm, which became the foot of Imperial Rome. [20]
The Roman measuring rod was 10 Roman feet long, and hence called a decempeda, Latin for 'ten-footer'. It was usually of square section capped at both ends by a metal shoe, and painted in alternating colours. Together with the groma and dioptra , the decempeda formed the basic kit for the Roman surveyors. [21] The measuring rod is frequently found depicted in Roman art showing the surveyors at work. A shorter folding yardstick one Roman foot long is known from excavations of a Roman fort in Niederburg, Germany. [22]
In the Middle Ages, bars were used as standards of length when surveying land. [23] These bars often used a unit of measure called a rod, of length equal to 5.5 yards, 5.0292 metres, 16.5 feet, or 1⁄320 of a statute mile. [24] A rod is the same length as a perch or a pole. [25] In Old English, the term lug is also used. The length is equal to the standardized length of the ox goad used for teams of eight oxen by medieval English ploughmen. [26] The lengths of the perch (one rod unit) and chain (four rods) were standardized in 1607 by Edmund Gunter. [27] The rod unit was still in use as a common unit of measurement in the mid-19th century, when Henry David Thoreau used it frequently when describing distances in his work Walden .
Two statues of Gudea of Lagash in the Louvre depict him sitting with a tablet on his lap, upon which are placed surveyors tools including a measuring rod. [29]
Seal 154 recovered from Alalakh, now in the Biblioteque Nationale show a seated figure with a wedge shaped measuring rod. [30]
The Tablet of Shamash recovered from the ancient Babylonian city of Sippar and dated to the 9th century BC shows Shamash, the Sun God awarding the measuring rod and coiled rope to newly trained surveyors. [31] [32]
A similar scene with measuring rod and coiled rope is shown on the top part of the diorite stele above the Code of Hammurabi in the Louvre, Paris, dating to ca. 1700 BC. [33]
The "measuring rod" or tally stick is common in the iconography of Greek Goddess Nemesis. [34]
The Graeco-Egyptian God Serapis is also depicted in images and on coins with a measuring rod in hand and a vessel on his head. [35] [36]
The most elaborate depiction is found on the Ur-Nammu-stela, where the winding of the cords has been detailed by the sculptor. This has also been described as a "staff and a chaplet of beads". [37]
The myth of Inanna's descent to the nether world describes how the goddess dresses and prepares herself:
She held the lapis-lazuli measuring rod and measuring line in her hand. [38]
Lachesis in Greek mythology was one of the three Moirai (or Fates) and "allotter" (or drawer of lots). She measured the thread of life allotted to each person with her measuring rod. Her Roman equivalent was Decima (the 'Tenth'). [39]
Varuna in the Rigveda, is described as using the Sun as a measuring rod to lay out space in a creation myth. [40] [41] W. R. Lethaby has commented on how the measurers were seen as solar deities and noted how Vishnu "measured the regions of the Earth". [42]
Measuring rods or reeds are mentioned many times in the Bible.
A measuring rod and line are seen in a vision of Yahweh in Ezekiel 40:2-3:
In visions of God he took me to the land of Israel and set me on a very high mountain, on whose south side were some buildings that looked like a city. He took me there, and I saw a man whose appearance was like bronze; he was standing in the gateway with a linen cord and a measuring rod in his hand. [43]
Another example is Revelation 11:1:
I was given a reed like a measuring rod and was told, "Go and measure the temple of God and the altar, and count the worshipers there". [43]
The measuring rod also appears in connection with foundation stone rites in Revelation 21:14-15:
And the wall of the city had twelve foundation stones, and on them were the twelve names of the twelve apostles of the Lamb. The one who spoke with me had a gold measuring rod to measure the city, and its gates and its wall. [44]
Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units or by various imperial or US customary units. The definition of length (cubed) is interrelated with volume. The volume of a container is generally understood to be the capacity of the container; i.e., the amount of fluid that the container could hold, rather than the amount of space the container itself displaces. By metonymy, the term "volume" sometimes is used to refer to the corresponding region.
A ruler, sometimes called a rule, scale or a line gauge, is an instrument used to make length measurements, whereby a user estimates a length by reading from a series of markings called "rules" along an edge of the device. Commonly the instrument is rigid and the edge itself is a straightedge, which additionally allows one to draw straight lines. Some rulers, such as cloth or paper tape measures, are non-rigid. Specialty rulers exist that have flexible edges that retain a chosen shape; these find use in sewing, arts, and crafts.
The cubit is an ancient unit of length based on the distance from the elbow to the tip of the middle finger. It was primarily associated with the Sumerians, Egyptians, and Israelites. The term cubit is found in the Bible regarding Noah's Ark, the Ark of the Covenant, the Tabernacle, and Solomon's Temple. The common cubit was divided into 6 palms × 4 fingers = 24 digits. Royal cubits added a palm for 7 palms × 4 fingers = 28 digits. These lengths typically ranged from 44.4 to 52.92 cm, with an ancient Roman cubit being as long as 120 cm.
The foot (pl. feet), standard symbol: ft, is a unit of length in the British imperial and United States customary systems of measurement. The prime symbol, ′, is a customarily used alternative symbol. In both customary and imperial units, one foot comprises 12 inches, and one yard comprises three feet.
The hand is a non-SI unit of measurement of length standardized to 4 in (101.6 mm). It is used to measure the height of horses in many English-speaking countries, including Australia, Canada, the Republic of Ireland, the United Kingdom, and the United States. It was originally based on the breadth of a human hand. The adoption of the international inch in 1959 allowed for a standardized imperial form and a metric conversion. It may be abbreviated to "h" or "hh". Although measurements between whole hands are usually expressed in what appears to be decimal format, the subdivision of the hand is not decimal but is in base 4, so subdivisions after the radix point are in quarters of a hand, which are inches. Thus, 62 inches is fifteen and a half hands, or 15.2 hh.
A unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. The most common units in modern use are the metric units, used in every country globally. In the United States the U.S. customary units are also in use. British Imperial units are still used for some purposes in the United Kingdom and some other countries. The metric system is sub-divided into SI and non-SI units.
A tape measure or measuring tape is a flexible ruler used to measure length or distance.
The rod, perch, or pole is a surveyor's tool and unit of length of various historical definitions. In British imperial and US customary units it is defined as 16+1⁄2 feet, equal to exactly 1⁄320 of a mile, or 5+1⁄2 yards, and is exactly 5.0292 meters. The rod is useful as a unit of length because integer multiples of it can form one acre of square measure (area). The 'perfect acre' is a rectangular area of 43,560 square feet, bounded by sides 660 feet long and 66 feet wide or, equivalently, 40 rods by 4 rods. An acre is therefore 160 square rods or 10 square chains.
The megalithic yard is a hypothetical ancient unit of length equal to about 2.72 feet (0.83 m). Some researchers believe it was used in the construction of megalithic structures. The proposal was made by Alexander Thom as a result of his surveys of 600 megalithic sites in England, Scotland, Wales and Brittany. Thom also proposed the megalithic rod of 2.5 megalithic yards, or on average across sites 6.77625 feet. As subunits of these, he further proposed the megalithic inch of 2.073 centimetres (0.816 in), one hundred of which are included in a megalithic rod, and forty of which composed a megalithic yard. Thom applied the statistical lumped variance test of J.R. Broadbent on this quantum and found the results significant, while others have challenged his statistical analysis and suggested that Thom's evidence can be explained in other ways, for instance that the supposed megalithic yard is in fact the average length of a pace.
Gunter's chain is a distance measuring device used for surveying. It was designed and introduced in 1620 by English clergyman and mathematician Edmund Gunter (1581–1626). It enabled plots of land to be accurately surveyed and plotted, for legal and commercial purposes.
The digit or finger is an ancient and obsolete non-SI unit of measurement of length. It was originally based on the breadth of a human finger. It was a fundamental unit of length in the Ancient Egyptian, Mesopotamian, Hebrew, Ancient Greek and Roman systems of measurement.
The palm is an obsolete anthropic unit of length, originally based on the width of the human palm and then variously standardized. The same name is also used for a second, rather larger unit based on the length of the human hand.
The ancient Egyptian units of measurement are those used by the dynasties of ancient Egypt prior to its incorporation in the Roman Empire and general adoption of Roman, Greek, and Byzantine units of measurement. The units of length seem to have originally been anthropic, based on various parts of the human body, although these were standardized using cubit rods, strands of rope, and official measures maintained at some temples.
A knotted cord was a primitive surveyor's tool for measuring distances. It is 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.
The earliest recorded systems of weights and measures originate in the 3rd or 4th millennium BC. Even the very earliest civilizations needed measurement for purposes of agriculture, construction and trade. Early standard units might only have applied to a single community or small region, with every area developing its own standards for lengths, areas, volumes and masses. Often such systems were closely tied to one field of use, so that volume measures used, for example, for dry grains were unrelated to those for liquids, with neither bearing any particular relationship to units of length used for measuring cloth or land. With development of manufacturing technologies, and the growing importance of trade between communities and ultimately across the Earth, standardized weights and measures became critical. Starting in the 18th century, modernized, simplified and uniform systems of weights and measures were developed, with the fundamental units defined by ever more precise methods in the science of metrology. The discovery and application of electricity was one factor motivating the development of standardized internationally applicable units.
The history of measurement systems in India begins in early Indus Valley civilisation with the earliest surviving samples dated to the 5th millennium BCE. Since early times the adoption of standard weights and measures has reflected in the country's architectural, folk, and metallurgical artifacts. A complex system of weights and measures was adopted by the Maurya empire, which also formulated regulations for the usage of this system. Later, the Mughal empire (1526–1857) used standard measures to determine land holdings and collect land tax as a part of Mughal land reforms. The formal metrication in India is dated to 1 October 1958 when the Indian Government adopted the International System of Units (SI).
Some approaches in the branch of historic metrology are highly speculative and can be qualified as pseudoscience.
Egyptian geometry refers to geometry as it was developed and used in Ancient Egypt. Their geometry was a necessary outgrowth of surveying to preserve the layout and ownership of farmland, which was flooded annually by the Nile river.
A number of different units of measurement were used in Sri Lanka to measure quantities like length, mass and capacity from very ancient times. Under the British Empire, imperial units became the official units of measurement and remained so until Sri Lanka adopted the metric system in the 1970s.