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101

Climate

ground. Sleighing commenced about the tenth of November and continued until about the same time in April, being five months.

The Great Lakes have a very sensible effect upon our climate, by equalizing the temperature-making the summers less hot and the winters less cold than they would otherwise be. Hence the difference between the mean temperature of winter and summer at Fort Snelling on the Mississippi river is about six and a half degrees more than at Fort Howard at the southern extremity of Green Bay; and at this place the influence of the lakes is but partially felt. Observations taken at more favorable stations, on the immediate shore of the Lakes would undoubtedly show a much greater difference. About the same difference is observed when we compare the mean temperature of winter and spring at the two places; the change from winter to spring being more sudden in the interior than on the lakes. This fact

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