E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Matthew Hopkins, who, in the middle of the seventeenth century, travelled through the castern counties to find out witches. At last Hopkins himself was tested by his own rule. Being cast into a river, he floated, was declared to be a wizard, and was put to death. (See above, Hammer for Witches.)