Dr. Forry on the Climate of the United States, ^"c. 29 



tinguished by great extremes of temperature, by seasons strongly 

 contrasted, and a corresponding dryness of the atmosphere, (un- 

 like the first two classes, in which the air is moist and the chan- 

 ges of the seasons slow and uncertain,) a constant and rapid suc- 

 cession is observed among the seasons. Summer, for example, 

 succeeds winter so rapidly that there is scarcely any spring, the 

 influence of which is surprisingly manifested in the vegetable 

 kingdom. As the summers of the third class are remarkable for 

 extremes of temperature, the mercury often rising in June, July, 

 and August, to 100° Fahr. in the shade, so the winters are equal- 

 ly characterized by extreme severity. From November to May, 

 cold weather prevails, the ground being often covered with snow 

 to the depth of three or four feet, and the general range of the 

 thermometer being from the freezing point to 30° below zero. 



The lowest temperature, taking the mean of a month, occur- 

 red at Forts Howard and Snelling. At the former, the mean 

 of the month of February, 1829, at 7 o'clock A. M., is -3°-17, 

 and the mean of December, 1822, at Fort Snelling, is — 3°-61. 

 This, it is to be observed, is merely the average of the morning 

 observations for the month. Although the extreme severity 

 of the winters at the posts remote from large bodies of water, 

 has been already fully illustrated ; yet the following remarks made 

 by Surgeon Beaumont when stationed in 1829 at Fort Crawford, 

 Wiskonsan, which is in the latitude of Fort Wolcott, R. T., may 

 be added in further elucidation : " The month of January was re- 

 markably mild and pleasant, the ground dry and free from snow, 

 and the Mississippi unusually low and unfrozen. February was 

 extremely cold, the weather clear and dry, and the thermometer 

 ranging during the month from the freezing point to 23° below 

 zero. From the 1st to the 16th, the mercury stood every morning, 

 with the exception of three, (the 6th, 7th, and 8th,) between —4° 

 and —23°, and did not rise above 20° above zero during these 

 days. On the 2d, 3d, 4th, 5th, 9th, 10th, 11th, 13th, 14th, and 

 15th, the mercury at sunrise stood respectively at 14°, 16°, 4°, 

 16°, 23°, 18°, 20°, 18°, 10°, 6°, and 4° below zero ; and on the 

 9th and 14th, it continued under —8° during the 24 hours. Du- 

 ring the month the prevailing winds were northerly and dry, and 

 the proportion of fair and cloudy weather was — clear twenty-two 

 days, cloudy three, variable one, and snowy two. The mean 

 depth of snow was about six inches. The month of March has 



