Image: Emperor Probus, Abraham Bogaert, De Roomsche Monarchy, 1697
Today's coin of interest is a coin of Emperor Probus from AD 280. I casually started to research this coin at my favorite Probus database, Probus Coins: http://probuscoins.fr/ The website and the associated book from Christophe Oliva, are outstanding resources on the coins of Probus. Coins have a lot of information with dates, officina, emission, descriptions, and more, searchable, with excellent images, and bibliography. Emissions are defined by a lot of tedious work to sequence in order the coins issued. Hoard evidence, die links and die studies are the type of evidence that goes into defining the order in which coins were issued.
As we don't have ancient written sources, emissions are subjective classifications by scholars who specialize in a particular coinage. These classifications are subject to revision and debate over time, as new evidence appears:
For the coinage of Probus, we rely on the emmissions proposed by Karl Pink, 'Der Aufbau der Römischen Münzprägung in der Kaiserzeit, VI/ 1 , Probus', NZ 73 (1949), 40
with later research on specific mints e.g.
Lugdunum mint: Pierre BASTIEN, Le monnayage de l'atelier de Lyon. De la réouverture de l'atelier par Aurélien à la mort de Carin (fin 274-mi-285), 1976.
Rome mint: Jean Guillemain: La monetazione di Probo a Roma (276-282 d.C.), Rome, Quasar, 2009, 286 p., 20 pl.
Siscia mint: Andreas Alfoldi: Siscia. Vorarbeiten zu einem Corpus der in Siscia geprägten römischen Kaisermünzen. Heft V. Verzeichnis der Antoniniane des Kaisers Probus, Budapest, 1939, 88.
Serdica mint: Gysen, P. "Nouvelles données concernant l'atelier de Serdica sous le règne de Probus" in RBN CXLVI (2000).
and others
My Probus coin has an interesting die link
The reverse of Salus from officina VI is a reverse die link with a different coin from Probus Coins 4644. Although the obverses are very different, this animation shows the perfect match of the two reverses overlayed:
The die link confirms the two issues were both 7th emission and same workshop. Not finding this coin in the Probus Coins database, I submitted it and it is now the "digital plate coin" Probus Coins 4980 (this coin):
Probus, AE Radiate, Siscia, AD 276-282, minted 280 AD, emission 7, officina 6, Bastien bust code H2,
Obv: IMP PROBVS P F AVG, radiate and mantled bust left, holding eagle-tipped sceptre.
Rev: SALVS AVG, Salus standing right, feeding serpent held in arms; VI to right, XXI in exergue (Type A)
Ref: RIC 748, Probus Coins 4980 (this coin)
Rarity: Scarce, the Salus from officina VI is a reverse die link with Probus Coins 4644