sentences:  The output of seamstresses dropped off when Martha was away, and spinners found they could slacken by playing the overseers off against her.Tools were regularly lost or damaged, thus stopping work, and Washington despaired of employing innovations that might improve efficiency because he believed the slaves were too clumsy to operate the new machinery involved.The most emphatic act of resistance was to run away, and between 1760 and 1799 at least forty-seven slaves under Washington's control did so.