While the building of the Minot's Ledge light had in it more of the picturesque element than attaches to the record of construction of the other beacons along the coast of the United States, there are but few erected on exposed points about which the builders could not tell some curious stories of difficult problems surmounted, or dire perils met and conquered. The Great Lakes, on which there are more than 600 light stations, offer problems of their own to the engineer. Because of the shallowness of their waters, a gale speedily kicks up a sea which old Ocean itself can hardly outdo, and they have an added danger in that during the winter they are frozen to such a depth that navigation is entirely abandoned. The lights, too, are abandoned during this season, the Lighthouse Board fixing a period in the early winter for extinguishing them and another in spring for reilluminating them. But between these dates the structures stand exposed to the tremendous pressure of such shifting floes of ice as are not found on the ocean outside of the Arctic regions. The lake lighthouse, the builders of which had most to apprehend from this sort of attack, is that at Spectacle Reef, in Lake Huron, near the Straits of Mackinaw. It is ten miles from land, standing on a limestone reef, and in the part of the lakes where the ice persists longest and moves out with the most resistless crush. To protect this lighthouse, it was necessary to build a rampart all about it, against which the ice floes in the spring, as the current moves them down into Lake Huron, are piled up in tumultuous disorder. In order to get a foundation for the lighthouse, a huge coffer-dam was built, which was launched like a ship, towed out to the reef and there grounded. When it was pumped out the men worked inside with the water surrounding them twelve to fourteen feet above their heads. Twenty months of work, or three years in time, were occupied in erecting this light. Once in the spring, when the keepers returned after the closed season to prepare for the summer's navigation, they found the ice piled thirty feet against the tower, and seventy feet above the doorway, so that they were compelled, in order to enter the lighthouse, to cut through a huge iceberg of which it was the core.