In Egypt the dirhem-system gives rise to two series of weights: that of the Oka and that of the Rottolo. In the latter word the Arabic ‘rotl’ is Italianised, the Arabic weights having come under Roman influence; an influence of long standing, since Al-Mamūn divided the Cantar after the Roman plan into 125 lesser rotl as well as into 100 greater rotl, when the Arabic gold Mithkal, 1/72 of the Egypto-Roman libra, took the place of the exagium solidi or aureus, 1/72 of the Roman mint-As. The Mithkal, or Miskal, = 72·74 grains, was divided into 24 Egyptian qirát = 3·03 grains, as the Aureus had been divided into 24 Roman Siliquæ = 2·92 grains, and 16 of the 24 qirát was the standard of the silver dirhem = 48·5 grains, _the lesser dirhem_. The golden Dinar, 21-3/4 qirát, was of the weight of the Attic commercial drachma = 65·6 grains; it displaced the Roman golden denarius. But the lesser dirhem, 2/3 the weight of the Mithkal, did not succeed in displacing an old-established drachma, which became a greater dirhem. For, as the Mithkal had a dirhem 2/3 of its weight, so the Roman Aureus, 1/6 of the As-ounce, had a silver drachma 3/4 of its weight. The As, originally 1/100 of the Greek-Asiatic talent, had its ounce divided, after the Greek system, into 8 drachmæ each 5049/(12 × 8) = 52·6 grains. Apparently this _greater dirhem_ tended, in Arab times, to fall towards the standard of the lesser dirhem = 48·5 grains. This is the probable explanation of the variations of the dirhems, and of the pounds based on them, along the Mediterranean coasts. In Tunis the dirhem = 48·58, almost exactly the original weight of the lesser dirhem. But in Tripoli there are two standards, 47·075 and 50·1 grains. The Ukyé or ounce is goldsmith’s weight, 10 dirhems of 47·075 grains; but in commercial weight it is in dirhems of 50·1 grains, so it is made the same weight by reckoning it as 150 kharūb or qirát instead of 160 of these as in the goldsmith’s ounce of 10 dirhems of 16 qirát. So there are variations in the weight of the dirhem basis of the Mediterranean pounds: In Egypt the dirhem = 47·66 grains In Tripoli „ = ⎧47·07 „ ⎩50·1 „ In Tunis „ = 48·58 „ In Morocco „ = 49 „ In Turkey „ = 49·6 „ The qirát, 1/16 of the dirhem, varies with it. _Egypt_ The Oka, = 2·723 lb., is 400 dirhems of 47·66 grs. The Rottolo, = 98 lb., is 144 dirhems of 47·66 grs. The Oka is a centesimal multiple of the dirhem. The Rottolo is an uncial multiple of it. 100 Rottoli = 1 Cantar = 98 lb.; this is the modern Egyptian Cwt. which has succeeded the Cantar of Al-Mamūn = 102·92 lb. _Turkey_