Digit (unit)
Encyclopedia
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.
In astronomy a digit is one twelfth of the diameter of the sun or the moon.
.
On surviving Ancient Egyptian
cubit-rods, the royal cubit is divided into seven palms of four digits or fingers each. The royal cubit measured approximately 525 mm, so the length of the ancient Egyptian digit was about 19 mm.
, the finger was one-thirtieth of a cubit length. The cubit was equivalent to approximately 497 mm, so the finger was equal to about 17 mm. Basic length was used in architecture and field division.
for the international inch
). The width of an adult human male finger tip is indeed about 2 centimetres. In English this unit has mostly fallen out of use, as do others based on the human arm: finger
(7/6 digit), palm (4 digits), hand
(16/3 digits), shaftment
(8 digits), span (12 digits), cubit
(24 digits) and ell (60 digits).
It is in general equal to the foot-nail
, although the term nail can also be used as 1/16 of yard and other units.
of Plutarch
, XII:23, but the definition as exactly one twelfth of the diameter may be due to Ptolemy
. Sosigenes of Alexandria
had observed in the 1st century AD that on a dioptra
, a disc with a diameter of 11 or 12 digits (of length) was needed to cover the moon.
The unit was used in Arab or Islamic astronomical works such as those of Ṣadr al‐Sharīʿa al‐Thānī (d.1346/7), where it is called iṣba' , digit or finger.
The astronomical digit was in use in Britain for centuries. Heath, writing in 1760, explains that 12 digits are equal to the diameter in eclipse of the sun, but that 23 may be needed for that of the moon, those over 12 representing the extent to which the Earth's shadow is larger than the Moon. The unit is apparently not in current use, but is found in recent dictionaries.
Si
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...
unit of measurement of length
Length
In geometric measurements, length most commonly refers to the longest dimension of an object.In certain contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured. For example it is possible to cut a length of a wire which is shorter than wire...
. It was originally based on the breadth of a human finger. It was a fundamental unit of length in the Ancient Egyptian
Ancient Egyptian units of measurement
-Length:Units of length date back to at least the early dynastic period. In the Palermo stone for instance the level of the Nile river is recorded. During the reign of Pharaoh Djer the height of the river Nile was given as measuring 6 cubits and 1 palm...
, Mesopotamian
Ancient Mesopotamian units of measurement
Ancient Mesopotamian units of measurement originated in the loosely organized city-states of Early Dynastic Sumer. The units themselves grew out of the tradition of counting tokens used by the Neolithic cultural complex of the Near East. The counting tokens were used to keep accounts of personal...
, Hebrew
Ancient Hebrew units of measurement
Biblical and Talmudic units of measurement, such as the Omer, used primarily by ancient Israelites, appear frequently within the Hebrew Bible as well as in later Judaic scripture, such as the Mishnah and Talmud...
, Ancient Greek
Ancient Greek units of measurement
Ancient Greek units of measurement would later create the foundation of Egyptian, and formed the basis of the later Roman system.Generally speaking, standards of measurement within the ancient Greek world varied according to location and epoch. Systems of ancient weights and measures evolved as...
and Roman
Ancient Roman units of measurement
The ancient Roman units of measurement were built on the Hellenic system with Egyptian, Hebrew, and Mesopotamian influences. The Roman units were comparatively consistent and well documented.-Length:Notes...
systems of measurement.
In astronomy a digit is one twelfth of the diameter of the sun or the moon.
Ancient Egypt
The digit, also called a finger or fingerbreadth, is a unit of measurement originally based on the breadth of a human finger. In Ancient Egypt it was the basic unit of subdivision of the cubitCubit
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....
.
On surviving Ancient Egyptian
Ancient Egyptian units of measurement
-Length:Units of length date back to at least the early dynastic period. In the Palermo stone for instance the level of the Nile river is recorded. During the reign of Pharaoh Djer the height of the river Nile was given as measuring 6 cubits and 1 palm...
cubit-rods, the royal cubit is divided into seven palms of four digits or fingers each. The royal cubit measured approximately 525 mm, so the length of the ancient Egyptian digit was about 19 mm.
| Name | |Egyptian name | 7 palms or 28 digits | 525 mm |
|---|---|---|---|
| Fist | 6 digits | 108 mm | |
| Hand | 5 digits | 94 mm | |
| Palm | |
4 digits | 75 mm |
| Digit | |
1/4 palm | 19 mm |
Mesopotamia
In the classical Akkadian Empire system instituted in about 2150 BC during the reign of Naram-SinNaram-Sin
Naram-Sin , reigned ca. 2254–2218 BCE, short chronology, was the third successor and grandson of King Sargon of Akkad. Under Naram-Sin the Akkadian Empire reached its zenith...
, the finger was one-thirtieth of a cubit length. The cubit was equivalent to approximately 497 mm, so the finger was equal to about 17 mm. Basic length was used in architecture and field division.
| Unit | Ratio | Metric equivalent |
Sumerian | Akkadian | Cuneiform |
|---|---|---|---|---|---|
| grain | 1/180 | 2.8 mm | še | uţţatu | |
| finger | 1/30 | 17 mm | šu-si | ubānu | |
| foot | 2/3 | 331 mm | šu-du3-a | šīzu | |
| 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.... |
1 | 497 mm | kuš3 | ammatu |
Britain
A digit (lat. digitus, "finger"), when used as a unit of length, is usually a sixteenth of a foot or 3/4" (1.905 cm1 E-2 m
Image:Length one to ten scale.svg|110px|right|Click on the top for smaller lengths and on the bottom for larger lengthspoly 0 0 20 20 0 20 Distances shorter than 1 centimetrepoly 0 200 200 200 220 220 0 220 Distances 10 centimetres or longer...
for the international inch
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
). The width of an adult human male finger tip is indeed about 2 centimetres. In English this unit has mostly fallen out of use, as do others based on the human arm: finger
Finger (unit)
A finger , is usually seven eighths of an inch or 2.2225 cm . The width of an adult human male finger tip is indeed about two centimetres. The inch, on the other hand, originates in the breadth of a thumb. In English this unit has mostly fallen out of use....
(7/6 digit), palm (4 digits), hand
Hand (unit)
The hand is a non-SI unit of measurement of length, now used only for the measurement of the height of horses in some English-speaking countries, including Australia, Canada, the UK and the USA. With origins in ancient Egypt, it was originally based on the breadth of a human hand...
(16/3 digits), shaftment
Shaftment
The shaftment is a unit of length, 6 - 6½ inches or 2 palms, i.e. 15.24 cm. A shaftment is the width of the fist and outstretched thumb. The lengths of poles, staves, etc...
(8 digits), span (12 digits), 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....
(24 digits) and ell (60 digits).
It is in general equal to the foot-nail
Nail (unit)
A nail, when used as a unit, is usually one sixteenth of a certain base unit. In English usage the most common base units were the foot and the yard for length, the acre for area and the hundredweight for mass....
, although the term nail can also be used as 1/16 of yard and other units.
Astronomy
In astronomy a digit is, or was until recently, one twelfth of the diameter of the sun or the moon. This is found in the MoraliaMoralia
The Moralia of the 1st-century Greek scholar Plutarch of Chaeronea is an eclectic collection of 78 essays and transcribed speeches. They give an insight into Roman and Greek life, but often are also fascinating timeless observations in their own right...
of Plutarch
Plutarch
Plutarch then named, on his becoming a Roman citizen, Lucius Mestrius Plutarchus , c. 46 – 120 AD, was a Greek historian, biographer, essayist, and Middle Platonist known primarily for his Parallel Lives and Moralia...
, XII:23, but the definition as exactly one twelfth of the diameter may be due to Ptolemy
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
. Sosigenes of Alexandria
Sosigenes of Alexandria
Sosigenes of Alexandria was named by Pliny the Elder as the astronomer consulted by Julius Caesar for the design of the Julian calendar. Little is known about him apart from Pliny's Natural History...
had observed in the 1st century AD that on a dioptra
Dioptra
A dioptra is a classical astronomical and surveying instrument, dating from the 3rd century BCE. The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand...
, a disc with a diameter of 11 or 12 digits (of length) was needed to cover the moon.
The unit was used in Arab or Islamic astronomical works such as those of Ṣadr al‐Sharīʿa al‐Thānī (d.1346/7), where it is called iṣba' , digit or finger.
The astronomical digit was in use in Britain for centuries. Heath, writing in 1760, explains that 12 digits are equal to the diameter in eclipse of the sun, but that 23 may be needed for that of the moon, those over 12 representing the extent to which the Earth's shadow is larger than the Moon. The unit is apparently not in current use, but is found in recent dictionaries.