1) The phrase ‘by task’ was a reference to piece-work, and in <i>c</i>.1570 John Kaye wrote <i>owt with thy plowghe Lett taskers thresh more strawe</i> (KayeCP). Employers would take on men at such rates under certain conditions.
1690 by Taske
1694 paid for getting by Taske, Farnley. The word has a much longer history and is the origin of the surname Tasker: 1341 Thomas Tasker, Ousthorpe
1379 Johannes Tasker, Sprotbrough. Found also in a minor place-name: 1544 un claus’ voc’ Taskerrod, Whitley.