Early Irish law texts record a wide variety of units of measurement, organised into various

systems A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and express ...

. These were used from

Early Christian Ireland Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early ...

(Middle Ages) or perhaps earlier, before being displaced by

Irish measure Irish measure or plantation measure was a system of units of land measurement used in Ireland from the 16th century plantations until the 19th century, with residual use into the 20th century. The units were based on " English measure" but u ...

from the 16th century onward.

Length

A ''troighid'' ("foot") was the length of a man's foot, divided into twelve ''ordlach'', "thumb-lengths". These figures assume a man's foot to measure . A ''magh-space'' was a unit set at the distance from which a cock-crow or bell could be heard. Other units such as ''inntrit'' and ''lait'' appear in documents; their value is uncertain, perhaps being equivalent to 1 and 2 ''fertach''s respectively. ''Ancient Laws of Ireland'' reads ''ceithri orlaighi i mbais, teora basa i troighid'' (4 thumb-lengths in a palm, 3 palms in a foot). and "Catalogue of the Irish manuscripts in the British Museum v.1" gives ''ceithri gráine an t-órdlach'' (4 grains in the thumb-length). ''Stair Ercuil ocus a bás: the life and death of Hercules'' mentions ''ceim curadh'' (warrior's paces).

Area

The basic unit of area was the ''tir-cumaile'', "land of three cows", as it was an area of land that was at some point worth three cows. It is sometimes erroneously interpreted as the area needed to graze three cows, but it is far too large for that; in modern Ireland, a cow grazes on about 0.4 ha, so twenty or more could graze a ''tir-cumaile''. Ireland in total covered about 870,000 ''tir-cumaile''.

Capacity

A hen's eggshell was used as a standard unit, roughly 55 ml.

Mass

The Manners and Customs of Ireland ''The'' () is a grammatical article in English, denoting persons or things already mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the m ...

lists two types of ''unge'': ''unge mór'' at 20

pennyweights A pennyweight (dwt) is a unit of mass equal to 24 grains, of a troy ounce, of a troy pound, approximately 0.054857 avoirdupois ounce and exactly 1.55517384 grams. It is abbreviated dwt, ''d'' standing for ''denarius'' (an ancien ...

(31.1 g) and ''unge beg'' at 10 pennyweights (15.6 g). A ' ( gold scruple) was used for measuring gold weight and was equal to a quarter-ounce (7 g).

Time

A night (''oídhche'') was used as a measure for time in preference to a day. As was normal for Islam and Jews and in line with the Bible (It was evening and morning of the first day), the Irish held that a new day began at sunset, not at sunrise, so that a Wednesday night would precede the day of Wednesday.

References