Sending a Signal

Sending a Signal. . , Dense fog on Lake Huron could spell disaster to vessels filled with passengers and valuable cargo. When fog was present and visibility was poor, mariners were forced to rely on sound to navigate their way into the St. Clair River. Early fog signals were simple hand bells rung from shore. With increased traffic on the lake, a more reliable system was added in 1871., Fort Gratiot's original fog signal was a[n] eight-inch steam whistle installed in 1871 north of the tower (seen on the right in the background photo). A second unit was added in 1881 to the south of the tower. In 1900 a new brick Fog Signal Building with a larger steam-powered diaphone replaced the two older whistles. An electric diaphone replaced the steam-powered system in the 1920's when the station was electrified. An electric oscillating signal tower was added to the site in the 1930's and in the 1970's, the fog horn systems where [sic] removed and replaced with a fog horn on buoy #7 in Lake Huron., [Bottom photo captions, from left to right, read] , The third fog signal building, built in 1900. Note the tall chimney, designed to keep hot ashes away from the building. Restoration of the building began in 2011., Blueprint showing the diaphone system, circa 1900., Assistant Keeper Wilkinson oiling the compressor on the diaphone system., The oscillating signal tower (electric) added in the 1930s.