The weights and measures of capacity seem a maze of confusion, until the clue is found. There is a double series of weights based on the dirhem and on the ounce. This ounce is not mentioned in the series of weights, but once discovered, it gives the clue to the maze, and the system is then seen to be really simple.
It has already been seen that the weights are in a double series giving the Oka of 400 dirhems, and the Cantar of 2000 Egypto-Roman ounces, = 124·7 lb., divided into 100 rottoli. The weight of the dirhem, = 49·5 grains in the cheké goldsmith’s weight, becomes = 49·6 in the Oka, 1/44 of the Cantar.
Fluid-measure.—A double cantar, 2 × 124·7 lb. = 249·4 lb., was increased in water-wheat ratio, 249·4 × 1·25 = 311·75 lb. = 31·175 gallons. The actual capacity of this water-Cantar is 31·412 gallons. This measure is divided into 100 rottoli-measure (= 3·14 lb. of water), each of 2-1/2 rottoli weight = 50 ounces.
Corn-measure.—The Cantar measure becomes, for corn, the Fortin, at a standard of 31·1 gallons. This measure being 2 × 1·25 = 2-1/2 times the Cantar weight of 2000 ounces, contains 5000 ounces of water or 4000 ounces of wheat. It is divided into 4 Killows of 7·775 gallons. This measure is evidently named from the Greek chilioi (Fr. kilo) as holding 1000 ounces of wheat. It is divided again into 4 Saa.
The Fortin is also divided into 88 rottoli, the rottolo containing 500 dirhems of water or 400 dirhems of corn.
In fluid-measure there is an oka-measure; 8 oka, = 3-2/3 rottoli-measure, make an Almud = 1·15 gallon. I only mention this intrusive measure to confer it with the Spanish Almuda or Celemin = 1·01 gallon.
These Turkish measures, fluid and corn, afford another instance of the practice of increasing a fluid measure in water-wheat ratio, and then of using this increased measure for fluids as well as corn. Instances of this practice have been seen in German measures (for instance the Himt). And our own gallon affords a somewhat similar instance. Increased from the cubic foot to make a corn-gallon, this was again increased by 3 per cent. to make the Imperial gallon, both for fluids and for corn.
Italy
The system of measures left from ancient Rome, themselves of Oriental origin, has been to a great extent overlaid by Arabic measures.
In Bologne the Corba, = 17·3 gallons, is half the cubed Black cubit, to which the Neapolitan oil-Salma, = 35·5 gallons, is closely approximate.