Lighthouse building on the Great Lakes demands the highest skill, incalculable ingenuity, and the soundest of design and workmanship. Consequently, some of the guardian lights distributed around these shores, such as Spectacle Reef, the Rock of Ages, Colchester, and Red Rock lighthouses, are striking evidences of the engineer’s handiwork. Of course, where the land presses in on either hand, transforming the waterway into a kind of canal, or where the shore is free from submerged obstructions, the type of lighthouse on either shore follows the wooden frame dwelling with a low tower, as it is completely adequate for the purpose. The one erection, however, which commands the greatest attention is the Spectacle Reef light, which has been called the Eddystone, or Minot’s Ledge, of the Lakes. In its way it was quite as bold an undertaking as either of these far-famed works, and in some respects was far more difficult to carry out, although the builder was spared the capriciousness and extreme restlessness of tidal waters. Spectacle Reef lighthouse rears its tapering head from a particularly dangerous reef in an awkward corner of Lake Huron, where commences the Strait of Mackinac, leading to Lake Michigan. The spot is dangerous, because it is covered by about 7 feet of water; awkward, because it occurs about ten and a half miles off the nearest land, which is Bois Blanc Island. The reef in reality comprises two shoals, which lie in such relation to one another as to suggest a pair of spectacles--hence the name. As it is exposed to 170 miles of open sea on one side, when these waters are roused the rollers hammer on the reef with terrible violence, while at times the currents skirl by at a velocity of two or three miles per hour, and the ice in its movement grinds, piles, and grates itself upon the reef in impotent fury. When this ice is forced forward with the push exerted by the currents, the pressure is tremendous and the force wellnigh irresistible. When the lighthouse was projected, it was realized that it would have to be of massive proportions and provided with adequate measures to protect it from the assault and battering of the ice. The task was undertaken by General O. M. Poe, who was engineer-in-chief to General Sherman on his historic march to the sea. This engineer decided to take the Minot’s Ledge monolithic structure as his model, seeing that the latter had withstood the savage onslaughts of the Atlantic. Fortunately, the foundations were of an excellent character, the reef being formed of hard limestone. [Illustration: _By courtesy of Lieut.-Col. W. P. Anderson._ BUILDING THE BARRE À BOULARD LIGHT IN THE RIVER ST. LAWRENCE. Owing to the severity of the ice piling in this waterway, the structures have to be provided with massive foundations.]