In the Roman Empire, a unit of land area, = 2 actus quadratus = 28,800 square pedes, assuming a pes of around 295 millimeters, roughly a quarter of a hectare or two-thirds of an acre. Hultsch (1862) set it at 2518.88 square meters. In concept, the amount of land that could be plowed by a team of oxen in one day.
The word comes from jugum, yoke, the yoke that harnessed a pair of oxen.
The principal subdivisions of the jugerum were based on the libra/uncia subdivisions, that is, it was divided in twelfths.
|area in square
Iugerum, quod quadratos duos actus habeat. Actus quadratus, qui et latus est pedes CXX et longus totidem: is modus acnua latine appellatur. Iugeri pars minima dicitur scripulum, id est decem pedes et longitudine et latitudine quadratum. Ab hoc principio mensores non numquam dicunt in subsicivum esse unciam agri aut sextantem, sic quid aliud, cum ad iugerum pervenerunt, quod habet iugerum scripula CCLXXXVIII, quantum as antiquos noster ante bellum punicum pendebat.
The iugerum consists of 2 actus quadratus. The actus quadratus, which in width is 120 pedes and the same in length, is called in Latin acnua. The smallest part of a iugerum is called a scripulum; it is a square 10 pedes in length and width. On this principle surveyors sometimes speak of the area beyond the [whole number of] iugerum as an uncia or a sextans, or the like, for the iugerum contains 288 scripula, which was the weight of the old as before the Punic War.
De rustica. Book 1, section 10.
iugum vocabatur, quod uno iugo boum in die exarari posset; actus, in quo boves agerentur cum aratro uno impetu iusto. hic erat cxx pedum duplicatusque in longitudinem iugerum faciebat. dona amplissima imperatorum ac fortium civium quantum quis uno die plurimum circumaravisset.
That portion of land used to be known as a “jugerum,” which was capable of being ploughed by a single “jugum,” or yoke of oxen, in one day; an “actus” it being as much as the oxen could plough at a single spell, fairly estimated, without stopping. This last was one hundred and twenty pedes in length; and two in length made a jugerum. The most considerable recompense that could be bestowed upon generals and valiant citizens, was the utmost extent of land around which a person could trace a furrow with the plough in a single day.
Although in concept 1 jugerum = area plowed in a day, in practice the area plowed depended on many factors, and the plowman was not necessarily expected to plow a jugerum a day.
The oxen employed in ploughing should be harnessed as tightly as possible, to make them plough with their heads up; attention paid to this point will prevent them from galling the neck. If it is among trees and vines that you are ploughing, the oxen should be muzzled, to prevent them from eating off the tender buds. There should be a small bill-hook, too, projecting from the plough-tail, for the purpose of cutting up the roots; this plan being preferable to that of turning them up with the share, and so straining the oxen. When ploughing, finish the furrow at one spell, and never stop to take breath in the middle.
It is a fair day's work to plough one jugerum, for the first time, nine inches in depth; and the second time, one jugerum and a half—that is to say, if it is an easy soil. If this, however, is not the case, it will take a day to turn up half a jugerum for the first time, and a whole jugerum the second; for Nature has set limits to the powers of animals even. The furrows should be made, in every case, first in a straight line, and then others should be drawn, crossing them obliquely. Upon a hill-side the furrows are drawn transversely only, the point of the share inclining upwards at one moment and downwards at another. Man, too, is so well fitted for labour, that he is able to supply the place of the ox even; at all events, it is without the aid of that animal that the mountain tribes plough, having only the hoe to help them.
The ploughman, unless he stoops to his work, is sure to prevaricate, a word which has been transferred to the Forum, as a censure upon those who transgress — at any rate, let those be on their guard against it, where it was first employed. The share should be cleaned every now and then with a stick pointed with a scraper. The ridges that are left between every two furrows, should not be left in a rough state, nor should large clods be left protruding from the ground. A field is badly ploughed that stands in need of harrowing after the seed is in; but the work has been properly done, when it is impossible to say in which direction the share has gone. It is a good plan, too, to leave a channel every now and then, if the nature of the spot requires it, by making furrows of a larger size, to draw off the water into the drains.
Pliny (the Elder), writing before 77 ce..
Book 18, portions of chapters 3 and 49.
John Bostock and H. T. Riley, translators.
The Natural History of Pliny, vol 4.
London: Henry G. Bohn, 1856.
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