Next let us see how from this unit grew their system. In several passages the shekel of the Sanctuary is said to consist of 20 _gerahs_[334], a word rendered simply by _obolos_ in the Septuagint. As before observed, the Hebrew metric system was essentially decimal, like that of Egypt; in fact had Tacitus been a metrologist he might have quoted this as an additional proof that the Jews were Egyptian outcasts, expelled by their countrymen because they were afflicted with a plague, perhaps the _scabies_[335], which so frequently affects swine. The measures of capacity, both dry and liquid, are decimal, and so accordingly we find a decimal division applied to the shekel. The latter is divided into two _bekahs_ (‎‏בֶּקַע‏‎, “a division,” “a half”), and each _bekah_ is divided into 10 _gerahs_ (‎‏גֵּרָה‏‎). The latter signifies “a grain” or “bean.” The Hebrew literature does not state what kind of seed or grain it was, although it is defined by Rabbinical writers as equal to 16 barleycorns. But the fact is that, as we see from the Septuagint rendering, the name in the course of time came to be considered simply as that of one-twentieth of the shekel, whether that shekel was the shekel of the Sanctuary, the Phoenician silver shekel of 220 grains, or the kings shekel of 260 grains used for copper and lead. The _gerah_ of the gold shekel or shekel of the Sanctuary was probably the most ancient and came closest to the natural seed from which it derived its name; this _gerah_ would be about 6½ grains (130 ÷ 20 = 6·5). On an earlier page (p. 194) we gave the weights of a number of grains and seeds of plants, and amongst them that of the lupin, called by the Greeks _thermos_. According to the ancient tables the _thermos_ is equal to two _keratia_, or _siliquae_ (the seeds of the carob tree); but since each _siliqua_ = 4 wheat grains, the _thermos_ = 8 wheat grains, or 6 barleycorns, or 6 Troy grains. If the wheat grain in Palestine was as heavy as that of Egypt or Africa (·051 gram, instead of ·047 gram.), the 8 wheat grains, would = 6·4 grains troy. Again, the Roman metrologists estimated the _lupin_ as the third part of the _scripulum_, which weighed 24 grains of wheat[336]; thus the Roman _lupin_ also = 8 wheat grains. We may therefore have little doubt that the _gerah_ was simply the _lupin_[337]. But what about the Rabbinical _gerah_ of 16 barleycorns? In the first place let us recall the confusion which exists in the Arab metrologists respecting the _habba_, some making three habbas, some four equal to the _karat_. This arose, as we saw, from confounding the wheat and barley grain. If the 16 grains assigned to the _gerah_ by the Rabbis are really wheat grains, all is at once clear. The _gerah_ to which they refer is that of the royal or double shekel (260 grs.), or in other words it is a double _gerah_. We have just found the _gerah_ of the Sanctuary shekel to be the lupin, and equal to 8 wheat grains, accordingly its double will contain