Myths and Legends of our Own Land, by Charles M. Skinner, , at sacred-texts.com
Ipswich had a very Old Harry in the person of Harry Main, a dark-souled being, who, after a career of piracy, smuggling, blasphemy, and dissipation, became a wrecker, and lured vessels to destruction with false lights. For his crimes he was sent, after death, to do penance on Ipswich bar, where he had sent many a ship ashore, his doom being to twine ropes of sand, though some believe it was to shovel back the sea. Whenever his rope broke he would roar with rage and anguish, so that he was heard for miles, whereon the children would run to their trembling mothers and men would look troubled and shake their heads. After a good bit of cable had been coiled, Harry had a short respite that he enjoyed on Plum Island, to the terror of the populace. When the tide and a gale are rising together people say, as they catch the sound of moaning from the bar, "Old Harry's grumbling again."
Now, Harry Main—to say nothing of Captain Kidd—was believed to have buried his ill-gotten wealth in Ipswich, and one man dreamed for three successive nights that it had been interred in a mill. Believing that a revelation had been made to him he set off with spade, lantern, and Bible, on the first murky night—for he wanted no partner in the discovery—and found a spot which he recognized as the one that had been pictured to his sleeping senses. He set to work with alacrity and a shovel, and soon he unearthed a flat stone and an iron bar. He was about to pry up the stone when an army of black cats encircled the pit and glared into it with eyes of fire.
The poor man, in an access both of alarm and courage, whirled the bar about his head and shouted "Scat!" The uncanny guards of the treasure disappeared instanter, and at the same moment the digger found himself up to his middle in icy water that had poured into the hole as he spoke.
The moral is that you should never talk when you are hunting for treasure. Wet, scared, and disheartened, the man crawled out and made homeward, carrying with him, as proof of his adventure, a case of influenza and the iron bar. The latter trophy he fashioned into a latch, in which shape it still does service on one of the doors of Ipswich.