This term is a contraction for semis tertius,
which is the Latin way of expressing
2 1/2 It may be used for various weights and measures: for example, pes sestertius
is 2 1/2 feet. But it has been more
usually applied to coin: the numus sestertius, sestertius, or, as it is
rendered in English, sesterce, was the unit according to which sums of money
were reckoned by the Romans almost throughout their history. It was
expressed on the coins themselves and in documents by the symbol ΗΣ
(two units and a semis), or with a line
through, H-S, a form commonly though incorrectly printed as ΗΣ.
According to the view of Mommsen (Röm.
p. 292), when silver coin was first issued at Rome
(B.C. 269: As, p. 205) it was based on the equation of the scruple of silver
(17.5 grains) to one libral as of 10 ounces, or 2 1/2 of the current reduced
asses of 4 ounces. Thus the denarius (10 asses) was equal to 4 sestertii,
and the quinarius to 2 sestertii. But this equivalence of the sestertius to
2 1/2 copper asses as current did not last long: in the time of the
Hannibalic wars it was decreed that thenceforth 16 asses should go to the
denarius and 4 to the sertertius, excepting in case of military pay, in
which the old relations were preserved. Up to that time, as the sestertius
and the libral as had been equivalent, money had been reckoned in either
indifferently; but thereafter the sestertius became the regular unit.
Shortly after its issue the sestertius fell in weight from 17 1/2 to 15
grains. After a time it ceased to be issued as a silver coin, though as a
quarter of the denarius it remained as money of account. M. Antony issued
sestertii in copper with the marks of value ΗΣ
that is, sestertii
of four asses. And Augustus ordained that the sestertius of 4 asses and the
dupondius of 2 should be struck in brass (orichalcum), while the as should
be minted in copper.
Sestertius of Nero in brass.
In reckoning sums of money the Romans sometimes, but not often, reckoned by
denarii. But far more usually they reckoned either by the libral as (in
which case aeris or aeris gravis would, be added) or by the sestertius,
which was originally the equivalent of the libral as. [AS
Sums up to a thousand sestertii were simply stated in sestertii. But sums of
several thousand sestertii were expressed as so many milia sestertiorum numorum
Thus decem milia sestertium
10,000 sestertii; and the same amount is sometimes expressed by the formula
where sestertia is usually
regarded as the plural of a neuter form sestertium (= 1000 sestertii),
though to this view there are grammatical objections. Sums of a million
sestertii and upwards are expressed by a use of the numeral adverbs in--ies; centena milia,
a hundred thousand, being
expressed or understood. Thus a million sestertii are decies centena milia sestertium,
a phrase abridged to [p. 2.668]decies sestertium.
and tricies sestertium
stand for two and three million sestertii,
and so on. As an example, we find in Cicero (Verr.
1.39, 100) 2,235,417 sestertii thus expressed: “vicies ducenta
triginta quinque milia quadringentos xvii numos” (i. e.
sestertios). The distinction between units, thousands, and hundreds of
thousands of sestertii is conventionally expressed merely by adding lines
above or beside the numeral: thus ΗΣΧ
= 10,000 sestertii or 10
X=decies sestertium or 1,000,000 sestertii.
The English equivalent of sums stated in sestertii cannot be accurately
ascertained, since different values will be given according to the relation
presumed between the value of silver and that of gold; but an approximation
sufficient for all purposes will be reached if the metal value of a
sestertius or sesterce is taken at two-pence, and that of a sestertium at
£8 sterling. What was as regards purchasing power the equivalent
of a sestertius in modern money, is a different and an insoluble problem.