3.0 2.5 4.5 1.9 5.2 2.5 6.5 W... 11.6 8.3 6.6 3.8 Cloudy.

May

64T44228

Mean

.....

38.96 45.35

40.71 41.67 84

17 101 3.9

From these tables we derive the following results: That the mean annual temperature of Fort Brady is nearly two degrees lower than that of Fort Wilkins, although the latter post is nearly a degree farther north. This difference arises from the insular position of Keweenaw Point, which is surrounded on three sides by water.

That, while the annual ratio of rain which falls at Fort Brady is 29.5 inches, at Fort Howard it exceeds 35 inches-an excess which cannot be accounted for by the difference in the mean temperature of the two places, but results from the prevailing direction of the winds; for while the N. and NW. winds prevail at the former post for more than one-third of the year, the S. and SW. prevail for a longer period at the latter.

That, while there are more rainy days at the former post-the ratio being as 118 to 86-the showers at the latter are more copious.

The direction of the winds is undoubtedly determined, in some degree, by the configuration of the country, pursuing the courses of the lakes.

The observations at Fort Wilkins and Mackinac do not extend through a sufficient number of years to enable us safely to institute comparisons. So far as relates to the annual amount of rain, they are defective.

In the subjoined table we have given the mean temperature of the year, and of the winter and summer, in corresponding degrees of latitude in western and southern Europe; also, the latitudes of places where the several lines of temperature correspond with those of the stations before given.

The first number in the column of temperature represents the mean annual temperature; that which stands in the place of a numerator, the mean temperature of the 'winter, while the denominator represents the mean temperature of the summer. The European observations are from Baron Humboldt's tables.

From these observations it would appear that the lines of equal temperature on the western coast of Europe, without reference to the elevation above the sea-level, are about 13° farther north than in the vicinity of the lakes. The climate at Fort Brady, during the whole season, corresponds in a remarkable degree with that of St Petersburg; indeed, the difference of temperature is less than between Fort Brady and Fort Wilkins. While the hills in the region of Fort Brady support a dwarfish growth of terebinthines, (resinous trees,) those in the vicinity of Nantes, in a nearly corresponding latitude in Europe, are covered with the vine.

*Humboldt has given the following as the proportional quantity of rain in different latitudes : 0. Mean annual depth

96 incl .

80

Table showing the mean temperature of the year, and of winter an mer, in corresponding latitudes in Europe and America.

Latitude.

Adjoining the great lakes Europe-height above sea. Mean temperaheight above sea.

ture of the year, of summer and win