dots on Constantinian coins
On the reverse of many Constantinian era coins, you may find a dot in the center. This is commonly referred to as a "centering dot". It is the consensus of most informed people that these dots were used in the manufacturing process. The authors of Late Roman Bronze Coinage believe these marks to be "merely operational". Some people occasionally think they have found a new variety, since the dot may or may not be mentioned in the reference they are using.
The question is how or why is the dot on the reverse. There are no historical records of the minting process that tell of this dot and no ancient paintings (why would there be....it was pretty mundane work back then) showing engravers at work. Of course, much information has been lost through the ages. We can re-create a very plausible way these dots were created, though.
The person that engraved the dies (referred to as a 'celator') during Roman times had a difficult job. He needed to make a starting point. When working with a circle, the starting point is generally the middle. Today a compass is used to trace a circle. If you have ever used one, you will recall that one arm of the compass is very sharp and it makes a small hole as it spins. This small hole is also in the middle of the circle. The Romans could very well have used something very similar to aid in the engraving process. The rest of the design would have been laid out in the circle and then the engraving process started.
note the dot between the V and O
Anything that was part of the coin design was carved out and the fields
were left alone (when coins are struck, the metal flows into the carved
out spaces). That is why the dot is found on some coins. If there was no
design in the center field, the dot would be left. This is why there is
never a dot on the obverse. The bust was engraved over the dot which completely
obliterated the small dot. Not all coins have a dot even if the field is
empty; this just means a celator took the extra time and filled the hole
or smoothed the dot out or the hole was gradually filled in (like a clogged
die) during striking process.
There is a series of Constantinian campgates from Antioch (starting at RIC 71) with a pellet in the doorway. I believe these pellets are really just centering dots (or at least, inspired by them). The other coins in the series have the dot before the SMANTA, but the campgates have it in the arch of the doorway (so it seems a stretch to include them to begin with). It seems (to me) that it is just another example of a centering dot left behind by an engraver(here is one from Thessalonica-the dot on this one is not called a control mark).On some of these coins the dot is not in the center, though. This leads me to believe that the engravers simply copied the dot from an earlier die, thinking it was part of the design (There is a PROVIDENTIA DEORVM QVIES AVGG of the Diocletian/Maximianus abdication issue from Cyzicus. It seems the celators copied a design from Trier because it has PTR (Trier) and K* (Cyzicus) as a mintmark!). I have also noticed the dots are not always centered on the Dafne coins. It seems to be only on the later series (RIC 35), which leads me to believe the engravers had started to think the dot was supposed to be part of the design; or maybe the purpose the engravers used the dot for did not require it being completely centered.
last modified on 11 Jan 2008