Decorated lead weights, circa 900

These weights were discovered in 1866 in a Viking grave at Islandbridge, just west of the centre of Dublin, and were first described by Oscar Wilde’s father, Sir William Wilde. They are pretty objects. Some are topped with gilt-bronze discs that were reused from stolen ecclesiastical metalwork, and others are trimmed with blue glass. The most impressive is in the form of a gilt-bronze animal head, with intricate decoration.

But the point of the objects is practical, not decorative. They are all of the same weight (26.6g), which, as Dr Pat Wallace, director of the National Museum of Ireland, has figured out, was the standard unit used in Viking Dublin. (That unit was slightly different from that used in the rest of the Scandinavian world.) What we see in these little objects is what can reasonably be called the beginning of capitalism in Ireland.

“It’s all about weighing silver,” says Wallace. “It’s from this process that we eventually get our first coinage in Ireland, in 997. This is the beginning of that: you’re a merchant, I’m a merchant, we’re doing a deal. We both have a weighing scales. We do the deal in silver, and we have a lead weight to make sure we’re not cheating each other.”

The Vikings used “hack silver” – cut-off bits of silver objects – as a kind of small change. They used the metal for arm and neck rings that functioned both as practical, portable wealth and as status symbols: literally, flashing the cash.

It is unclear whether such weights as these were used in Ireland before the Vikings: none has been found, but linguistic evidence suggests they were known.

What is certain, though, is that the Vikings brought with them the idea of an internationally tradable currency. In the ninth and 10th centuries they flooded Ireland with huge quantities of silver, which was the basis for their whole monetary system.

Some of it originated in raiding (the known haul of silver from Vikings raids on Frankish territory in the ninth century alone is 20 tonnes). Much of it came from trading with the Islamic world. It was mined in central Asia, brought to the

great Arab cities and thence sent, as payment for trade goods, up the Russian rivers and on to Sweden. This shiny metal is thus the tangible form of a wave of economic globalisation breaking over Ireland.

A system of standard weights implies a lot more than increased trade. Someone has to set the standards and then police them. Tighter political control of this kind is possible in towns, and Dublin became the largest urban centre in Viking Ireland. It was founded twice: first in the 840s as a longphort, a base for ships and raiding parties; and then, more permanently, as a defended town around 917.

The weights shown here come from the first phase of settlement: it is possible, but not certain, that the original longphort was at Islandbridge. What is clear from the weights, though, is that Viking merchants had a presence in the Dublin area even before it emerged as a fully fledged town. They were pioneers of the Irish market economy.

Thanks to Dr Pat Wallace

Where to see it National Museum of Ireland – Archaeology, Kildare Street, Dublin 2, 01-6777444, museum.ie