NOTE.—Contains on reverse, Dates on which navigation was possible and on which navigation opened at ports on Great Lakes during last 6 years.—Highest velocity of wind, direction, and date of occurrence, during Mar. 1900-12.—Average depth of snow on ground and average thickness of ice in harbors, in inches, during Mar. 1900-12.—Total amount of snow, in inches, unmelted, during Mar. 1900-12.—Direction and percentage of prevailing winds at stations on Great Lakes during Mar. 1900-09.—Approximate location of submarine signal bell stations, Mar. 1911.—Distribution of radiotelegraph stations on Great Lakes, and call letters for each.
The meteorological charts and supplements of the north Atlantic, north Pacific, and Indian oceans, and the Great Lakes, monthly, and of the south Atlantic and south Pacific oceans, quarterly, are issued by the Weather Bureau for gratuitous distribution to cooperating shipmasters and others interested in ocean meteorology.