I remember about 1660 there was a great difference between him and Sir Hierome Sanchy, one of Oliver's knights…The Knight had been a Soldier, and challenged Sir William to fight with him. Sir William is extremely short sighted, and being the challengee it belonged to him to nominate place and weapon. He nominates, for the place, a darke Cellar, and the weapon to be a great Carpenter's Axe. This turned the knight's challenge into Ridicule, and so it came to nought.

"Sir William Petty" - Brief Lives