1) A weir is now most commonly thought of as a dam, placed across a river to restrict and control its flow rather than stop it altogether. Formerly, it had several meanings connected with river defences and these can be linked with bridges and the strengthening of river banks. Most commonly, it referred to an embankment reinforced by piles.
That was probably what was meant in 1340 by ‘one rood of wer at the bank of the water of Colyn’. This referred to the river Colne at Dalton, near Huddersfield. More specifically, the tenants of Bradford manor ‘made a weyre with pylles’ in 1422. Maps of 1598 and 1625 which had to do with disputes over ‘steaners’, that is places where a river had changed its course, show weares that had been built to defend the new line of the stream. Tenants were often help responsible for making and maintaining the defences: 1512 ‘enjoined on Robert Ward that he shall make a fence called a wer ... next the Haire’ [river Ayre], Methley
1558 make and upholde the wayres betwixt the water of Calder and the said holme, Copley
1626 making and maintayning ... one water weare att the foote of the said dam twentie yeards in length downewardes along after the side of Damhead Close ... from wasting by the violence of the said river, Armitage Mill
A document of 1581 contains an order to the tenants of Hartshead to make sufficient the weares and workes defendinge the meadow from the Callder . Occasionally the word was also used as a synonym for ‘wing’ or ‘wing wall’, most explicitly in 1701 when a new bridge was built over the Laver: Alsoe to make a wing or weare of hewen stone upp above the said road on the East side of the water betwixt the road and where the old bridge now standeth with a point to goe into the watercourse beyond the foundation of the Landstall on that side .