Lead Weights from Akrotiri: Preliminary Observations

These artifacts are important indicators of the manner in which the craftsmen and merchants of the site perceived, evaluated, and dispensed some commodities, and hence they have the potential to provide valuable information about economic interconnections in the Bronze Age Aegean when compared with their counterparts at other sites.

This paper presents the results of a metrological analysis of the gram values of the Akrotiri balance weights with a view to determining the absolute values of the standard units that were in use. The study is a portion of an on-going project which includes the collection, examination, publication, and mathematical analysis of all surviving metrical artifacts from the prehistoric Aegean.

It is argued herein that most of the balance weights from the site (nearly all of which are lead discs) are scaled on a system of weight whose main denominations were in the vicinity of 60 - 64 g and 480 - 510 g. Important clues about the design of the system come from several pieces which bear simple incised marks, and suggestions are offered as to how these marks are to be interpreted. Parallels with marks on weights from other sites suggest, not surprisingly, that weight measurement at Akrotiri was performed on the rather common and geographically widespread Minoan system. It can be demonstrated that the units of weight referred to in the Linear A and Linear B accounts are reflected in the surviving balance weights from Akrotiri and other Minoan sites.

The possibility must be considered that a second system of weight was in use concurrently with the Minoan before the LM I destruction of the site. If another system existed at Akrotiri, however, it seems to have been a secondary one, and we can say very little about its units, scaling, and origin.

The excavations at Akrotiri between 1967 and 1973 have yielded one of the largest single collections of prehistoric balance weights in the Aegean ⁽¹⁾. These humble objects provide important clues as to the absolute units of weight measurement in use in Thera during the Bronze Age. The purpose of this paper is to present the results of a metrological analysis of the weights of these items and to demonstrate, with occasional reference to balance weights and systems at other sites, that the craftsmen and merchants of Akrotiri measured weight on a system common elsewhere in the prehistoric Aegean.

The most common and most easily recognizable type of balance weight from Bronze Age Aegean sites is the simple lead disc. Fifty-seven such objects, ranging in weight from 11.8 to ca. 5800 grams, have been found thus far at Akrotiri.

The discs were quite easily manufactured, either by pouring a specific amount of molten lead onto a flat surface and crimping the edge inward all around when cooled (as described in Caskey 1969, 101, fig. 2) or, in some cases, simply by pouring the lead into an open shallow dish mould. In either case, lead lent itself readily to the manufacture of balance weights; if a finished disc were tested and found to be overweight, it would have been chiseled or carved down to the proper mass. If underweight, it would have been remelted and supplemented in a second pouring.

In compensation for this convenience of manufacture, lead does have a few disadvantages which frustrate the historical metrologist's efforts to recover the system or systems of absolute values on which such pieces were scaled. Lead is soft and batters easily, and even with normal use a lead balance weight will evidence dents and gouges which promote flaking of its outer surface, thus rendering it underweight. Furthermore, lead objects oxidize readily on contact with humic acids in the soil, taking on a crust which often renders them overweight.

One cannot, therefore, expect ancient lead balance weights to conform to the same degree of accuracy as their well-preserved counterparts in stone, let alone modern balance weights. In trying to recover an ancient system of absolute weight values one must allow a rather wide range of tolerance. Skinner (1954, 781) has proposed that, in general, a tolerance in the vicinity of ± 5 % of the gram values of ancient balance weights be allowed, and this seems quite reasonable for stone weights; because of the physical and chemical instability of lead, though, it would be prudent to increase this figure slightly for our purposes here.

We must search, then, for clusters of gram values among the weights, and try to relate the clusters in a simple and logical manner.

These are the weights in grams of 61 identifiable balance weights found at Akrotiri (all are lead discs unless otherwise noted).

Aiding us in our attempt to recover the system(s) of weight in use at Akrotiri are the incised or impressed marks on several of the discs and one of the stones.

If it can be demonstrated mathematically that at least some of these marks were value indicators, we should then be in a position to assign quantitative denominations to the respective balance weights, and to outline the mechanics of the system on which they were scaled. Among the 71 total objects inventoried as balance weights from the site, these nine are peculiar in that special attention was paid to their manufacture.

I have recently presented a detailed model of the Minoan system of weight measurement, based upon the work of Evans (1906), Bennett (1950), Caskey (1969), and my own study of marked balance weights from eight Bronze Age sites in Crete and the Cyclades (Petruso 1976, Kadmos, forthcoming). It can now be demonstrated that the Minoans used symbols with some consistency to denote fractions and multiples of a unit of ca. 60  - 64 g and of ca. 480 - 510 g (the latter unit being the Minoan mina, equivalent in weight to eight of the former).

That most of the marked weights from Akrotiri were scaled on the Minoan system can be shown easily. The four dots on nos. 39 and 44 point to a unit of just over 60 g per dot. Nos. 40, 41, and 42 also may be assigned to this popular denomination, which is represented in the Linear B accounts by the symbol # (Bennett 1950, 211, fig. 6; Ventris and Chadwick 1973, 57-8). No 6 bears an incised triangle and weighs precisely one-third of our unit of just over 60 g ⁽²⁾ . That this aspect of "threeness" was intended by the person who carved the symbol finds confirmation in a lead disc from Ayia Irini which is marked with an incised triangle and weighs 20.1 g (Caskey 1969, 96 (no. 7), fig. 1, pl. 53) and in another lead disc from Mochlos, marked with three dots and weighing 19.4 g (Herakleion Museum, Case 55, no. 93). 

The Minoan mina is indicated by the symbols on no. 52, which bears two triangles. Dividing the weight of the piece by two yields a value of ca. 510.6 g per triangle. I suggest that the peculiar shape of no. 34 also carried value information.

The cross brings to mind "fourness", and the piece weighs one-fourth of a Minoan mina of 478.4 g. The marks on nos. 7 and 11 elude us (in fact they might not be value symbols). Finally no. 49, whose four dots point to a unit of 176.1 g per dot, does not seem at first glance to be scaled on the Minoan system.

The unit indicated is, however, within the range of the cluster represented by the weights of nos. 35 - 37, which may be attributed as 3-unit pieces. Perhaps this denomination had some special use or was reserved for the measurement of a specific commodity.

A simple pattern of binary, duodecimal, and sexagesimal factors, all of which would have been useful denominations, readily presents itself. The Minoan system of weight measurement can be invoked for most of the larger weights at Akrotiri. Surely many of the smaller pieces which were not attributed in Table III were also members of this system; in general, though, they have suffered more than the larger discs, and their preservation precludes any secure metrological attributions.

Evans set the weight of the Minoan talent at ca. 29 kg, which is very close to the mean weight of 19 well-preserved oxhide ingots from Haghia Triada (see most recently Parise 1967, 345). Until recently, the only archaeological evidence for a balance weight of this mass had been the pyramidal stone bearing a relief carving of an octopus, found in the West Magazines of the Palace of Minos (Evans 1906, 342-3, fig. 1). In the 1973 excavations at Akrotiri another object, unique in its own way and certainly a balance weight, was found (Marinatos 1976, 32, pl. 56a). It is a very thick lead disc with a bronze handle, in an excellent state of preservation, which weighs approximately 15 kg and thus, as Marinatos suggested, would have functioned as a half-talent weight.

What of the well-preserved lead weights from this site which do not fit the Minoan system? It is tempting to see another contemporary system or systems reflected in these pieces. The corpus of Minoan and Mycenaean balance weights which I have been compiling for several years currently contains some five hundred pieces, only half a dozen of which can be attributed to the well-known Egyptian and Near Eastern systems, and I am inclined to believe that these items made their way to the Aegean as curios. To judge from the surviving archaeological evidence, the sanctioned absolute standards of weight used by the Minoans and referred to in the Linear B tablets were Aegean sui generis. By the third phase of the Late Bronze Age another, less well understood system seems to have come into use in mainland Greece. The evidence for this system is sketchy: the total number of balance weights known from Mycenaean sites is remarkably small.

It is at once suprising and unfortunate that no mainland weights have been found which bear markings that might give clues as to their systems or absolute standard values. The possibility that some of the Akrotiri balance weights were scaled on a non-Minoan system, even as early as the LM I period, cannot be ruled out.

We will need many more balance weights from other Aegean sites, however, before we are able to write a more detailed history of Aegean weight metrology.

- (1). I should like to thank Dr. Christos Doumas for permitting me to examine and weigh at the site the unpublished lead balance weights from the Akrotiri excavations. Dr. Ioannis Sakellarakis kindly made available to me the balance weights currently on display in the Thera gallery of the National Museum in Athens. Some of the weights dealt with here have been published by Marinatos (1969, 48 - 50, pls. 19, 41; 1971, 38, pls. 87, 88).

- (2). Marinatos (1969, 49 and 49 - 50, n. 1) argued unconvincingly that the triangle inscribed on this weight indicated that it was a 2½ - shekel weight on the Babylonian system. He saw as a possible parallel to this simple symbol a potter's mark on a Melian vase said to be from Thera, but he proposed neither an interpretation of that mark nor a reason why the balance weight and the pot should share it.

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