Standard weight

These three fragments of glass belong to a standard weight of 500g which was originally a disc with a round hole in the centre. The disc seems to bear the traces of an imperfect moulding process. A rectangular mark was imprinted in two places on the upper surface. Five lines in ancient Kufic script can be made out; they specify the nature of the object: a glass weight weighing twenty ūkīya, guaranteed by an official stamp dated Hegira 127 (AD 745). The name of the governor mentioned on the standard is well known: ‘Abd al-Rahmān ibn Habīb, the grandson of ‘Uqba ibn al-Nāfī’, who governed the Maghreb between 744 and 754 after returning from Spain, where he had taken refuge following the disastrous battle of Tangiers.

This weight is similar to what is called a sanja, a word of Persian origin that designates either a standard that is used to verify weights in circulation, or the weight itself. Most of the weights in the Muslim world are made of glass, but some are made of bronze and differ from one place to another and from one era to another. The tenth-century Arab traveller and geographer al-Muqaddasi brings this question up in one of his texts: he mentions that in Muslim Spain and along the Barbary Coast during the Fatimid era, the weights in use were the ratl and the sanja. Ratls in conformity with the Baghdad type were made of lead; they were periodically withdrawn from circulation to be melted down again and were then marked with a stamp which bore the name of the Caliph. The sanjas that were known were made of glass and marked with a circular stamp. Shaped like a disc and very light in weight, they were the general kind intended for the purpose of checking weights and coins. Several sanjas are preserved that are similar to the standard of Mila, two discoid Egyptian ratls. One, dated 737 (431 g.), is conserved in the Cairo Museum and the other, dating from the period of ‘Abd al-Rahmān ibn Yazīd (764–769) (433 g), in the Jungfleisch collection.

The weight and monetary value of the ūkīya, whose Greek name shows through beneath the Arabic form of the word, was always variable in the Muslim world, as were the other units of weights and measures used in verifying and standardising aspects of sales and purchases and in commercial trade.

The use of these measures is an ancient practice: they were already known in Babylonia, Egypt and the Greek cities. Amongst the palaeo-Babylonian Akkadians, the weight standards varied depending on the object being weighed. A large number of such weights in a variety of shapes are preserved; some are metal but usually they are made of stone. This is borne out by the Akkadian term aban kīsi, the Hebrew equivalent of which is qikoā, meaning “stone in a purse”.

These precious weights and measures were kept in prestigious places; the Hebrews placed them in the Temple, the Athenians established a company responsible for guarding the original measures and inspecting the calibration. The Romans kept them in the Capitol, in the temple of Jupiter. In Byzantium, the Emperor Justinian had all the weights and measures checked in order to keep the originals in the main church of Constantinople. In France, from the year 650, under Dagobert, measure standards were kept in the king’s palace.