The Chronology of Second Century Ptolemaic Bronze Coins:
Two Different Methods to Graphically Interpret Weight/Size Data

Graphing of weight data versus Svoronos numbers gives an illustration of the chronology of 2nd century bronze coinage


This page, and the parts that follow, show that F&L's weight and size data can be used with Svoronos' numbers not only to give an illustration of the relative chronology of second century bronze coinage but also to give corrections to F&L's reattributions of several types of coins.

As shown below, the chronological aspect of the types can be made numeric by the use of Svoronos numbers and the result is a useful graphic illustration (see RP-Graph-1, left) of the weight versus chronology of second century Ptolemaic bronze coinage.

Click here to see a larger image of RP-Graph-1

Svoronos’ catalogue numbers are widely used to indicate a specific type of coin listed in his monumental compilation of Ptolemaic coins. His cataloguing placed related coins into series with later series having greater Svoronos numbers. Therefore, a Svoronos number not only indicates a specific coin type but may also give a distinct numeric indication of relative chronology that can be used in scatter graphing. However, adjustments must first be made to those few Svoronos numbers where attributions have been changed (mainly because of new hoard data) since production of his catalogue in 1904. Then, for each type of coin in the data tables, Svoronos numbers are used with scatter graphing to give a meaningful presentation of average weights (g) versus chronology (Sv numbers); the results are shown in RP Graph 1 above.

Click  RP ANALYSIS  to see the method of development of RP Graph 1

The well-organized pattern with cohesive columns of data-points in RP Graph 1 successfully shows the various series of related coins produced during periods involving four consecutive regencies. They are, from left to right the ‘helmeted head’ series with the Athena head coin of Ptolemy IV (c.205 BC); the so-called Isis series of Ptolemy V (204-180 BC); the Necropolis hoard coins of Ptolemy V (204-180 BC) and of Ptolemy VI (after 180 BC); the coins of Ptolemy VI (180-170 BC) with co-regent Cleopatra I (180-176 BC); and, finally on the right, three examples of coins with the two-eagle reverse type produced by Ptolemy VI (180-c.170) and continuing with co-regent Ptolemy VIII (before 164 BC).

RP Graph 1 shows average coin weights according to the relative chronology (from c.205 to c.164 BC) implicit in Svoronos numbers. RP Graph 1 does not ‘prove’ Svoronos’ assignments. It illustrates a chronological pattern where all the weight/size data are consistent with updated attributions and, in contrast to F&L Table 3, are also in agreement with all previously accepted attributions.

 Results from Comparisons of RP Graph 1 with F&L Table 3

In several different ways, RP Graph 1 corrects the attributions given in the invalid F&L Table 3: (1) The earliest known coins to contain high percentages of lead were produced in the time of Ptolemy V (204-180 BC), not after 180 BC in the times of Ptolemy VI and Ptolemy VIII; (2) the Zeus-Ammon/double eagle coins Sv1423, Sv1424-A and Sv1424-B were not markers of the same denomination produced over widely different times after 204 BC; and (3) a comparison of the size (diameter in millimeters) of coins produced after 180 BC with their Svoronos numbers shows that denominational marking by obverse and/or reverse types did not occur.

Firstly, RP Graph 1 shows results related to the metallic composition of the coins; superimposed near many of the data points are indications of coin composition (HL = High Lead) where examples of these coins have been found with high percentages of lead (the data is from F&L Appendix 3, pp. 69-72). For example, RP Graph 1 shows that the HL Isis Series of Ptolemy V was produced earlier than coins of Ptolemy VI (with co-regent Cleopatra I) that began in 180 BC. F&L Table 3 distributes the Isis coins piecemeal into three different periods of time (6b, 6c and 7c) beginning c.205 BC and possibly ending as late as 146 BC.

Because three Isis series coins (Sv 1235, 1239, 1240) revealed high lead content consistent with Series 7a and 7b and were unmarked they were placed into F&L series 7c (that does not appear in F&L Tables 2 and 3). F&L state that Series 7c possibly did not commence until [after 146 BC], i.e., in the time of Ptolemy VIII. However, with their high lead content the three Isis series coins should not have been displaced from their universal assignment to Ptolemy V (204-180 BC); they belong together (as in RP Graph 1) with other unmarked Isis coins of Ptolemy V (Sv1234, Sv1236) that have the identical obverse/reverse as well as high percentages of lead.

Five of the seven examples of coins in the Pt V Isis Series column have high lead concentrations (15.6% to 33.3%). It has previously been accepted that the earliest examples of Ptolemaic bronze coins known to contain high percentages of lead were those attributed to Ptolemy VI (i.e., after 180 BC). As shown by HL in RP Graph 1, it now has become clear that, rather than as late as 146 BC as suggested by F&L, it was at least in the time of Ptolemy V (204-180 BC) that adulteration of bronze coinage with relatively inexpensive lead was initiated, apparently to reduce the cost of production and to increase the money supply during this especially difficult period in Ptolemaic history.

Secondly, in their erroneous F&L Table 3, F&L took six Zeus-Ammon/double eagle coins, and one single-eagle coin Sv1375 (22g), as the same denomination; this includes Sv1423 (38g) said to be produced by Ptolemy IV (c.204 BC in series 6a and 6b), Sv1424-A (30g) (in series 6c), and Sv1424-B (22g) in series 7c (said to be possibly after c.146 BC in the time of Ptolemy VIII). However, as shown in RP Graph 1, these coins are simply three different denominations that began production 180-c.170 in the time of Ptolemy VI. F&L have recently abrogated the assigning of these coins before 180 BC and they should consequently now be returned to their classical chronology as different denominations of Ptolemy VI after 180 BC. For a review of the various assignments of these coins, Click -

Click  Re-attributions of the two-eagle coins of Ptolemy VI 

Thirdly, between weight and related size, the more important element that determines denominational value is size. Using Svoronos sizes as indicating denominations, a table (developed below) of diameters and Svoronos' sizes gives a general view of second century BC coinage after 180 BC. This involves putting together the major coins of the second century, i.e., the two-eagle coins Sv1423-8, together with coins listed in F&L's Table of Hoards. A comparison of diameters using Svoronos sizes shows that five of the seven denominations of Sv1423-8 and Sv1375-87 circulated together in 180-c.145 BC each with two, or more, different obverse types, i.e., the same denomination had two, even three, different obverses. It is thereby again shown, in a different way, that there was no policy of denominational marking by obverse and/or reverse types: In the third, second, and first century BC, denominations were determined by weight and corresponding size. Click -

Click  Comparisons of sizes and obverses for Ptolemaic bronze coins produced in 180-c.145 BC 

Finally, click below for a summary of results and conclusions.