1) Workmen used the word ‘sow’ for a large oblong piece of solidified metal, from the fifteenth century at least.
The cast pig-iron at a furnace flowed into a ‘runner’, a depression in a bed of sand, and then into branched channels known as ‘sows’. The name is said to have arisen because this pattern resembled piglets feeding from a sow. In 1701, Robert Sorsby’s shop in Sheffield contained sow metall Boxes. The analogy is absolutely clear in the accounts of ironworks in Sussex: in 1542-3, for example, money received for swine pannage drew a distinction between Sowes, pygges and shottes: stocks of iron in 1563 were similarly referred to as Sowes and Shott. The ‘shott’ was a young pig, one that had been weaned.
2) A common alternative spelling of ‘sough’.
1539 shall kep oppyn his watter cowrce cawilyd a sowe, Ossett: 1590 turne one water course ... or else sowe it under the grounde into the Calder, Dewsbury
1598 liberty for sinkeinge, soweinge and making of pitts, Thornton
1655 opening a sowe upon Baildon Moor
1701 for repair of the way … damaged per that coal pitt sow, Horton
1718 John Smith for by worke in the Sow, Farnley.