Submitted by Petr Vesely on
Founded 26-Apr-2006
Last update 28-Sep-2011
Unstruck Serrate Flan Basic Observations References
Identification Number SXX-AE-01
| Ruler: | Uncertain Seleukid king1 |
| Mint: | probably Ake-Ptolemais or Antioch2 |
| Period: | 2nd century BC |
| Denomination: | AE Unit |
| Weight: | 5.52 g |
| Diameter: | 15 - 16 mm |
| Obverse: | – |
| Reverse: | – |
| Die axis: | – |
| References: | Houghton, Lorber and Hoover, SC II, Vol. II, p. 60, Fig. 11 (this coin) |
Basic Observations
Many Seleukid bronze coins produced at mints in Syria and Phoenicia bear small central cavities (dimples), sometimes accompanied by surrounding concentric circular scratches. As the coin MSE-AE-07 presented in the 2nd part of this collection shows, this phenomenon also occurs on some municipal coins from the Seleukid period. Similar central cavities and concentric scratches are also found on many Ptolemaic bronze coins and in the bronze civic coinage issued by many cities in Moesia, Thrace and Asia Minor under the Roman Empire. Several possible explanations of these marks were published.5 The most plausible theory argues that cast flans were installed on a lathe in order to smooth its faces with a tool. This tooling was responsible for the concentric circular marks. By some authors, the cavities were either drilled or hammered into the cast flan so that it could be easily installed on the lathe. According to Welsh, Lathe Machining of Bronze Coin Flans, a centering pin of the lathe was forcibly impressed into the flan, creating the dimple. As the central cavities seldom match from obverse to reverse, a lathe with two centering pins was not used. The flans were probably turned on a rotating platen, similar to a potter’s wheel, and held in place by a single centering pin positioned over one of the central cavities.6 Nevertheless, as for the Seleukid bronzes, the true purpose of lathe turning is unclear yet.7
The following four visual observations are either in accord with the theory of lathe processing mentioned in the previous paragraph or at least do not contradict this theory. All these observations refer only to the unstruck flan SXX-AE-01 presented above and to the obverse of the municipal coin MSE-AE-07 which is presented on the page devoted to the municipal coinage of Seleukeia in Pieria. A reliable judgment of the first observation would probably require a destructive metallurgical microstructural analysis. The second and third observations are well-known from many other coins too. The fourth observation should be verified on other specimens to exclude a possible mistake.
Observation 1: The central cavities of the unstruck flan have raised edges, see Figures 1 and 2 (sides 1 and 2, respectively). It indicates that these cavities were forcibly impressed by a centering pin of a lathe or, less probably, somehow hammered into the cast flan.8 In any case, it seems to be sure that they are not artifacts of a casting process.
As for the obverse of the municipal coin, it is not possible to visually decide if the edge of the cavity was raised or not, because of the striking process which deformed it.
Observation 2: The center of concentric circular scratches do not coincide with the center of the flan. Compare white and yellow circles on Figures 3b, 4b and 5b. The white circle always represents an approximation of the border of the flan (without the serrate edge in the case of the unstruck flan), whereas the yellow circles represent the clearest visible scratches. The white and yellow crosses represent the centers of the white and yellow circles, respectively. It is clearly visible that the white and yellow crosses do not coincide.
These auxiliary graphical objects were constructed as follows: Several points were chosen on the clearest visible scratches on large photos of the coins. These points are denoted by red crosses on Figures 3a, 4a and 5a. Thereafter, these selected scratches were approximated by concentric circles via a computer program in such a way that the circles optimally fit the chosen points (the distance of each point from the corresponding circle is less than 1% of the diameter of the circle). The white circles representing the border of the flan were positioned manually.
It is necessary to emphasise, as Welsh notes on p. 5 of his study Lathe Machining of Bronze Coin Flans, that it is not clear whether the scratches are really concentric circles (such as would be cut by irregularities in a fixed tool) or a continuous spiral (such as would be cut by a tool moving across a rotating flan).
Observation 3: The cavities on the unstruck flan do not match each other from one side to the other, see Figures 6 and 7. The white circle represents borders of the central cavity on the given side of the flan, whereas the blue circle represents borders of the central cavity on the opposite side (imagine that the flan is transparent). It means that a lathe with two centering pins was certainly not used to smooth the faces with a tool.
These auxiliary graphical objects were constructed as follows: Three reference points were chosen on the edge of the flan such that these points are visible both form the obverse and from the reverse. Thereafter a composition of a rotation, of a translation and of a dilation was found by a computer program so that the reference points on the image of the obverse coincide with the reference points on the image of the reverse which was specularly reversed with respect to the vertical axis. Afterwards this planar transformation was used for computation of the position of the unvisible opposite central cavity.
Observation 4: It seems that the concentric circular scratches on the unstruck flan do not perfectly match with the central cavities (their centers do not coincide), see Figures 3b and 4b. To demonstrate this fact more clearly, the center of the yellow circle on the first side of the flan was manually set to coincide with the geometrical center of the cavity. Thereafter, the diameter of the yellow circle was found via a computer program to optimally fit the chosen points denoted by the red crosses, see Figure 8. It is visible that the shifted yellow circle does not fit the points well (the maximum deviation of the selected points from the corresponding optimal circle is now greater than 5% of the diameter of the circle). Figure 9 shows the same experiment for the second side of the flan. The modified yellow circles again do not fit some of the red crosses, although it is not so evident as on the first side (the maximum deviation is visible on the points corresponding to the smallest circle and it is equal nearly to 4% of the diameter of the circle). On the other hand, it seems that the center of the concentric circular scratches match the center of the central cavity quite well on the municipal coin, see Figure 5b.
The importance of this observation is not clear. It is possible that the bottoms of the central cavities on the unstruck flan are not exactly conical, so that a single centering pin of a lathe did not press the flan exactly in the geometrical center of the cavity. In any case, this phenomenon should be proved also on other specimens with visible circular scratches and central cavities before any conclusion is made.
1 Serrate coins were minted from Seleukos IV to Alexander II. See Houghton, Lorber and Hoover, SC II, Vol. II, pp. 62-75 (Appendix 2C by Oliver D. Hoover, Table of Seleucid bronze fabric by ruler and mint).
2 Serrate coins were produced nearly exclusively at Ake-Ptolemais mint and Antioch mint, but some serrate issues are also known from Seleukeia on the Tigris, Tyre, Apamea and some uncertain mints. See Houghton, Lorber and Hoover, SC II, Vol. II, pp. 62-75 (Appendix 2C by Oliver D. Hoover, Table of Seleucid bronze fabric by ruler and mint).
3 The thunderbolt was a frequent symbol on the coins of Seleukeia in Pieria. The thunderbolt was a cultus-object of Zeus Keraunos (“Zeus of the Thunderbolt”) and, according to Appian, Syriake, 9.58, it was connected with the foundation of the city: They say that when he (Seleukos I) was about to build the two Seleucias (Seleukeia in Pieria and Seleukeia on the Tigris) a portent of thunder preceded the foundation of the one by the sea, for which reason he consecrated thunder as a divinity of the place. Accordingly the inhabitants worship thunder and sing its praises to this day.
4 The Seleukid Era is based on a lunar calendar, beginning with the autumn of 312 BC. It means that if x is a Seleukid year (and x<312) then the corresponding BC time interval is from 313–x to 312–x.
The beginning of the Seleukid Era was set as follows: In 311 BC, shortly after capturing Babylon, Seleukos I Nikator began the enumeration of his satrapal years there. However, after his decisive victory over Antigonos Monophthalmos in 307/6 BC, he backdated his “fictitious” first regnal year to coincide with Nisanu 1, 311 BC (New Year’s Day in the Babylonian calendar). This marked the antedated epoch of the Seleukid calendar according to the Babylonian reckoning. Later in 305/4 BC, when Seleukos I took the diadem and assumed the royal title “King”, he retained the numbering of his regnal years in Babylon but employed the Makedonian calendar and thus pushed his accession year back to Dios, 312 BC (Dios was the first month of the Makedonian calendar; it corresponds to October-November). This became the antedated epoch of the Seleukid era on the Macedonian calendar. (Assar, Recent Studies in Parthian History, Part I, p. 6)
The Seleukid Era was used at least until the first century AD in some Eastern countries.
5 See Houghton, Lorber and Hoover, SC II, Vol. II, pp. 58-60 (Appendix 2C by Oliver D. Hoover, Mechanical processing).
6 For a detailed description, see Welsh, Lathe Machining of Bronze Coin Flans, pp. 7-8.
7 See Houghton, Lorber and Hoover, SC II, Vol. II, pp. 58-60 (Appendix 2C by Oliver D. Hoover, Mechanical processing).
8 Drilling the cavity would tend to create a recess without a noticeably raised edge. (Welsh, personal communication)
References:
- Appian:Roman History, Book XI - The Syrian Wars. Translated by Horace White. Macmillan and Co., New York, 1899. (The Perseus Digital Library, http://www.perseus.org/cgi-bin/ptext?lookup=App.+Syr.+1.1; Livius.org, http://www.livius.org/ap-ark/appian/appian_syriaca_00.html)
- Assar, Gholamreza F.:Recent Studies in Parthian History, Part I. The Celator, Vol. 14, No. 12 (December 2000), pp. 6-22.
- Hoover, Oliver D.:The Handbook of Syrian Coins: Royal and Civic Issues, Fourth to First Centuries BC. The Handbook of Greek Coinage Series, Vol. 9. Classical Numismatic Group, Inc., Lancaster / Pennsylvania - London / England, 2009. (abbr. HSC)
- Houghton, Arthur; Lorber, Catharine; Hoover, Oliver:Seleucid Coins, A Comprehensive Catalogue. Part II, Volumes 1 and 2. The American Numismatic Society, New York, in association with Classical Numismatic Group, Inc., Lancaster/London, 2008. (abbr. SC II)
- MacDonald, George:Catalogue of Greek Coins in the Hunterian Collection, University of Glasgow. Volume 3. Further Asia, Northern Africa, Western Europe. Elibron Classics, Adamant Media Corporation, 2003. Replica edition of the edition published by James Maclehose and Sons, Glasgow, 1905. (abbr. Hunterian Coll. III)
- Welsh, David:Lathe Machining of Bronze Coin Flans. Published on the author’s website Classical Coins, http://www.classicalcoins.com (retrieved April 26, 2006).
- Welsh, David:personal communication. (April 2006)
- Wroth, Warwick:British Museum Catalog of Greek Coins, Volume 20: Greek Coins of Galatia, Cappadocia and Syria. London, 1899 (reprint, Arnaldo Forni, Bologna, 1964). (abbr. BMC 20)