Myths and Legends of our Own Land, by Charles M. Skinner, [1896], at sacred-texts.com
Dunderberg, "Thunder Mountain," at the southern gate of the Hudson Highlands, is a wooded eminence, chiefly populated by a crew of imps of stout circumference, whose leader, the Heer, is a bulbous goblin clad in the dress worn by Dutch colonists two centuries ago, and carrying a speaking-trumpet, through which he bawls his orders for the blowing of winds and the touching off of lightnings. These orders are given in Low Dutch, and are put into execution by the imps aforesaid, who troop into the air and tumble about in the mist, sometimes smiting the flag or topsail of a ship to ribbons, or laying the vessel over before the wind until she is in peril of going on beam ends. At one time a sloop passing the Dunderberg had nearly foundered, when the crew discovered the sugar-loaf hat of the Heer at the mast-head. None dared to climb for it, and it was not until she had driven past Pollopel's Island—the limit of the Heer's jurisdiction—that she righted. As she did so the little hat spun into the air like a top, creating a vortex that drew up the storm-clouds, and the sloop kept her way prosperously for the rest of the voyage. The captain had nailed a horse-shoe to the mast. The "Hat Rogue" of the Devil's Bridge in Switzerland must be a relative of this gamesome sprite, for his mischief is usually of a harmless sort; but, to be on the safe side, the Dutchmen who plied along the river lowered their peaks in homage to the keeper of the mountain, and for years this was a common practice. Mariners who paid this courtesy to the Heer of the Donder Berg were never molested by his imps, though skipper Ouselsticker, of Fishkill,—for all he had a parson on board,—was once beset by a heavy squall, and the goblin came out of the mist and sat astraddle of his bowsprit, seeming to guide his schooner straight toward the rocks. The dominie chanted the song of Saint Nicolaus, and the goblin, unable to endure either its spiritual potency or the worthy parson's singing, shot upward like a ball and rode off on the gale, carrying with him the nightcap of the parson's wife, which he hung on the weathercock of Esopus steeple, forty miles away.