4. The Beládi Cubit (c. 300 B.C.)
The new Persian cubit, known as the Beládi (from belád, country), had the advantage, first, of a simple relation to the Parasang or meridian league of 30 stadia = 1/20 degree; secondly, of it being divisible into two feet of convenient length.
The meridian mile being = 6080 feet or 72,960 inches the parasang is therefore 3 × 72,960 = 218,880 inches; and the Beládi cubit, 1/10000 of the parasang, was therefore = 21·880 inches. This is the length that John Greaves gave in 1645 as his measurement of what he called the Cairo cubit, one of the different standards that have accumulated in Egypt during sixty centuries.
The Beládi cubit is still to be found in the East. A half Beládi cubit = 10·944 inches, a convenient foot for Eastern use, passed to Spain with the Moors and became the Burgos foot, the standard of which was allowed to go astray after the fall of the Moorish dominion. But the Spanish shore-cubit (Covado di ribera) still exists at the standard of 21·9157 inches.
The Beládi cubit is that used by Posidonius (131-53 B.C.). He gave the circumference of the globe as 240,000 stadia, which = 666·66 to the degree, or 11·111 to the meridian mile of 6080 feet or 72,960 inches, 72,960/11.111 = 6566 inches or 10 fathoms of 65·66465 inches, exactly 3 Beládi cubits or 6 half-cubits.
It is interesting to find this Greek philosopher, settled in Rome, reckoning the circumference of the globe accurately on the basis of the Beládi cubit of Persia. Coupling this with the use by the Hebrews of the Bereh equatorial cubit brought back from the Captivity, the date of the Beládi meridional cubit is evidently at some centuries before the Christian era.
The Bereh or Equatorial Land-mile.
The Jews brought back from the Captivity a measure known as the Cubit of the Talmud. It was 1/3000 of a mile, called the Bereh, which was said to be 1/24000 the circumference of the earth. Now this latter fraction corresponds to one-thousandth of an hour of longitude, or of 15 degrees on the equator, and thus points to the Bereh being an equatorial, not a meridian mile. It is still extant in the Turkish dominions in Asia. While the modern, as the ancient, Persian Parasang is 1/7200 of the meridian, the Turkish Farsang of 3 Bereh should be 3/24000 = 1/8000 of the equatorial circumference—
1/8000 of 2029·11 yards × 60 × 360 = 5478·6 yards.
This corresponds very closely to the length of the farsang, which is 5483·9 yards. The Bereh, by calculation, is 1826 yards and the Talmudic cubit, 1/3000 of it, = 21·914 inches.