Contents

Irish units of measurement

Atroighid ("foot") was the length of a man's foot, divided into twelve ordlach, "thumb-lengths". These figures assume a man's foot to measure 25 cm (9.8 in).

Amagh-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 fertachs 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).^[1] 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[edit]

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[edit]

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

Mass[edit]

The Manners and Customs of Ireland lists two types of unge: unge mór at 20 pennyweights (31.1 g) and unge beg at 10 pennyweights (15.6 g).^[2]

Ascrepall óir (gold scruple) was used for measuring gold weight and was equal to a quarter-ounce (7 g).^[3]

Time[edit]

Anight (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.

See also[edit]

• List of obsolete units of measurement
• Metrication in Ireland
• Irish measure

References[edit]

• Joyce, P. W. (1906). "23: Measures, Weights, Mediums of Exchange". A Smaller Social History of Ancient Ireland. Retrieved 20 May 2015.
• "tir cumaile [Old Irish]". sizes.com. Sizes, Inc. 1 September 2008. Retrieved 20 May 2015.
• Seebohm, Frederic; Hugh Exton, Seebohm (1914). "2: The Irish units of tribute and food-rent". Customary acres and their historical importance, being a series of unfinished essays". Longman's, Green, &co. Retrieved 20 May 2015.