Trust in metal-weight exchange: the role of weights

How did Viking merchants know whether or not to trust their trading partner? For coin users like us, value is guaranteed by a central political authority (as well as our perception that the coin is not a forgery).  But in a bullion or metal-weight system, there was no equivalent of the Bank of England. Imagine a scenario in which a trader from Norway agreed a sale with a trader from Scandinavian England. Who decided which weight standards to use, and the degree of accuracy achieved in the weighing of silver? Why would you trust the scales and weights of someone you didn't know, and probably wouldn't meet again?

One way of ensuring trust in metal-weight transactions across different trading communities was to use standardised weights based on established weight units. By using a widely known, visually distinct and, most importantly, reliable weight type, a trader could help to boost confidence in their trading credentials. Like the picture of the queen on a bank note, standardised weights provided visual cues that added credibility to a transaction.

A cubo-octahedral weight from Yorkshire, with 4 dots.
Copyright: J Kershaw

In the Viking Age, there were two main types of standardised, or regulated weight associated with the weighing of silver: oblate-spheroid weights, which I wrote about here, and a second type, called cubo-octahedrals. These are copper-alloy weights in the shape of a cube with facetted corners (for which reason, they are sometimes described as 'dice' weights). These two different weight types were based around a common weight unit and could therefore be used together. But whereas oblate-spheroid weights weigh between 7 and 150g, cubo-octahedrals are much lighter, typically weighing between 0.75 and 4g.

For standardised weights to be effective, they must be visually recognisable and have a consistent weight, which is not easily falsified. This is certainly the case for cubo-octahedrals, which are distinguished by the appearance of 1 to 6 punched dots of their six square sides (and sometimes, as on this example, a single dot on the smaller, triangular surfaces). The purpose of these dots has been debated. Some have interpreted the dots as representing the position of the weight within a set. But this seems unlikely to me. For a start, the dots number 1, 2, 3, 4 or 6, but never 5. There is also emerging evidence that the number of dots relates to the weight of the item. Each dot appears to represent approx. 0.75g, meaning that a weight with, say, three dots will weigh in the region of 2.25g (3 x 0.75). Weights that have survived into the present day may be corroded, which can make it difficult to determine their original weight. This weight above, with four dots, weighs 2.61, which is close to the proposed target of 3g (4 x 0.75). In principle, I think it's fair to say that cubo-octahedrals wear their weight on their sleeve. A 'fake' would be easy to spot when handled, or when placed on the scale.

Map of cubo-octahedral weights (excluding those found at the Viking winter camp sites of Torksey (Lincs) and 'ARSNY'). The size of the diamond is scaled to the number of weights.

For interested colleagues, this is an updated version of Steuer's often reprinted map from 1997, showing all weights known to me as of March 2013. Copyright: J Kershaw

In order to be trusted by traders in different markets, standardised weights also had to cross national borders. Indeed, both Viking-Age types are found across the Scandinavian world, including in England. The map above shows that cubo-octahedral weights are found from Russia to Ireland, with many finds from the Danelaw (the area of northern and eastern England settled by the Scandinavians in the ninth century). However, the overall density of finds is rather different. Whereas in Scandinavia, the weights are found in large numbers at urban and market centres (the larger diamonds on the map), in England the distribution is more rural, and single finds are the norm. Somewhat surprisingly, there are no known clusters from Viking towns such as York or Lincoln. Why this is the case is an open question, but it is clear that cubo-octahedrals were in regular use by Scandinavian settlers in the rural Danelaw. They probably used them mainly to trade with each other, and perhaps occasionally with merchants from the Scandinavian homelands.