|Sestertius of Hadrian (Spink 638a, RIC 913; A.D. 122; extremely rare)|
Obverse: HADRIANVS AVG COS III P P
'Hadrian Augustus, three times consul, father of his country.'
Reverse: EXERC BRITANNICVS S C
'For the army of Britain, by order of the Senate.'
Coin currently in B.M. Department of Coins and Medals (gallery 49, case 14)
on loan from the collection of G. Cope. [Images used with permission.]
The emperor Augustus made a great many reforms during his years in office (27BC-14AD), and in 24BC the Roman monetary system came under his close scrutiny. His standardised coinage was minted in seven denominations using four different metals; gold, silver, brass and copper.
These basic denominations were augmented or replaced by various other coinage issues, particularly during the frequent economic crises of the later empire.
The Aureus was the highest denomination coin of the old Republic, and remained so for most of the Roman Imperial period. They were minted in gold of a very high purity, and valued at twenty-five denarii or silver pieces. The weight fixed by Augustus at the beginning of the first century was 7.75 grammes, and this remained fairly constant up until the reign of Septimius Severus (193-211AD) when it weighed around 7.2 grammes, but by the reign of Gallienus (253-268AD) this had been reduced to only 2.45 grammes. Throughout this time the purity of gold used to make the aureus remained fairly constant, with the result that the coin became somewhat reduced in size.
During the early Republic these silver coins were struck in almost pure metal, but by the time of Claudius the coin had been debased, and contained a significant quantity of copper alloyed with around 3.5 grammes of silver. The weight and fineness of the denarius fluctuated markedly throughout its lifetime, and the intrinsic silver content was constantly being reduced, so that by the middle of the third century, during the reign of Gallienus, the silver content was only 0.08 grammes. The introduction of the antoninianus into the monetary system by Emperor Caracalla quickly forced the denarius out of circulation, and after 244AD denarii were no longer issued with many being over-struck by the state and converted into antoniniani.
Made from orichalcum,¹ a mixture of copper and tin somewhat like brass. These coins were minted in large quantities during the republic, but their value declined during the empire making their production no-longer economical.
The sesterce was represented in writing by the Latin symbols for 2½, properly II
S. The symbol S representing the fraction was standard Latin shorthand for semis, meaning 'half'. In latter times II S became transformed to HS, which is the most commonly recognized modern format.
This was the standard monetary unit and Copper coin of ancient Rome. The as and its diminutives, the semis 'half-piece' and quadrans 'quarter-piece' were produced in vast quantities during the Republic but with galloping inflation they became almost valueless by the second century AD. The word as, Latin for 'unity', is thought to stem from the ancient Etruscan language. The as was also an early Roman unit of weight, approximately equal to 1 pound Troy or 373 grammes.