Chaldron

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

A chaldron is an old English dry-volume unit mainly used for coal. The word comes from cauldron. It was used from the medieval period and, officially, it stayed on the books until 1963, though after 1835 coal began to be sold by weight.

Two main types were used: Newcastle and London chaldrons. The Newcastle chaldron covered coal from Northumberland and Durham. In 1421 it weighed about 2,000 pounds, but its weight grew over time because taxes charged per chaldron. By 1678 it was fixed at 5,880 pounds (52.5 long hundredweight), and in 1694 it was set at 5,940 pounds (53 long hundredweight).

The London chaldron was defined differently: 36 heaped bushels, each bushel the size of a Winchester bushel plus 1 imperial quart, roughly 19.5 inches in diameter. This worked out to about 3,140 pounds.

The chaldron was a volume measure, not a precise weight, so the actual coal weight depended on lump size and water content. It was also the legal limit for horse-drawn coal wagons on roads, since heavier loads could damage roadways. Railways used special “chauldron wagons” about 10 feet long.

Merchants could cheat by buying coal in large lumps and selling it in smaller pieces. This practice helped prompt the 1835 act, which required coal to be sold by weight from 1836 onward.