Tron: Scotland’s Public Weighing Scales

The tron at Stenton, East Lothian, Scotland. Image credit: Studio Karel/Shutterstock.com

This is the village of Stenton, in East Lothian, Scotland—a small agricultural village made up of a couple of buildings and patches of farmlands. In the medieval period, the main produce of the village was grain, hides and wool, which were sold at the markets every week. The cross like arrangement seen in the image above marks the site where the markets were held up to the middle of the 19th century.

The horizontal arm of this cross is the top bar of a weighing balance used to weight goods sold at the market. You can still see the hooks at either ends of the bar, from which weights and goods were hung. This kind of public balance is called a tron, from the French word troneau, meaning 'balance'. At one time trons such as this were a common sight across rural Scotland.

Before standardization of weights and measurements, much of Europe used the Imperial system of measurement used by the Romans. But after the fall of the Empire, standard measures diverged in different parts of Europe, so that by the early Middle Ages standards differed from place to place. The Scottish measures, which differed from the measures in England, used troy and avoirdupois to measure weights. The troy weight was used by silversmiths to measure gold, silver and gemstones, and by apothecaries to measure medicines and chemicals. Avoirdupois weight was used to measure bulkier goods like grains.

Market Scene by Pieter Aertsen , circa 1550. 

Certain burghs—an administrative unit similar to a city or a town—were entrusted with the responsibility of keeping the standards. Edinburgh kept the 'ell' for linear measure, Linlithgow the 'firlot' for dry measure, Lanark the 'troy stone' for weight, and Stirling the 'pint' for liquid capacity. Each burgh kept their own sets of weights to be used during market days, but they were seldom uniform, so that weights varied from burgh to burgh.

The public weighing machine, the tron, was one of the key places of the burgh. The street where it was situated was often known as the Trongate, and the tron was also the site of public meetings as well as punishments.

In 1824, the Imperial Weights and Measures Act attempted to introduce uniformity in weights and measures across Scotland, and by the middle of the 19th century Scottish weights and measures disappeared and were replaced by Imperial units. An attempt was made to introduce metric units to the UK and abolish the archaic Imperial measures as early as 1868, but it was not until the late 20th century that a gradual process of phasing out Imperial measures was begun in the UK. Today, most pre-packaged goods sold in the UK are labelled in metric units.