Mark (Orkney Weight)

The base unit of the Norse weight system of Orkney and Shetland, never authoritatively standardised.

This is the most unsettled unit in the archive, and the reason is documented. When Orkney and Shetland passed to Scotland the islands kept their own weights, but no Scottish authority ever fixed a standard for them and no physical standard was maintained.

So the sources disagree irreconcilably. Eighteenth and nineteenth-century writers give the mark at anywhere between eighteen and twenty-two ounces, one declaring twenty-two the most just; a certificate obtained from Bergen gives eight. Nothing reconciles them.

What filled the vacuum was interest. Robert Stewart, Earl of Orkney, and his son Patrick are both blamed in the record for increasing the weights by which tenants paid, and a later lawsuit on the question was decided for the landlord on the ground of prescription — long use rather than correctness.

It is a clean demonstration of why standards are a public good. Where nobody is obliged to keep one, the party doing the weighing decides.