NOTE.—Contains on reverse, Direction and percentage of prevailing winds at stations on Great Lakes during Apr. 1900-09.—Total amount of snow, in inches, unmelted, during Apr. 1900-12.—Highest velocity of wind, direction, and date of occurrence during Apr. 1900-12.—Approximate location of submarine signal bell stations.—Distribution of radiotelegraph stations on Great Lakes, and call letters for each.