| January | 20°,75 | July | 84°,8 | |
| February | 32 | August | 83 | |
| March | 48 | September | 63 | |
| April | 59 | October | 52 | |
| May | 72 | November | 41 | |
| June | 83°,75 | December | 27 |
The temperature of the Atlantic under this parallel is 62, but the standard of this part of the globe is the North Pacific, which is here 4 or 5 degrees colder than the Atlantic. The Yellow Sea is the nearest to Pekin, being about 200 miles distant from it; but it is itself cooled by the mountainous country of Corea, which interposes between it and the ocean, for a considerable part of its extent. Besides, all the northern parts of China (in which Pekin lies) must be cooled by the vicinity of the mountains of Chinese Tartary, among which the cold is said to be excessive.
The greatest cold usually experienced during this period was 5°, the greatest heat, 98°: on the 25th of July, 1773, the heat arose to 108° and 110°: a N. E. or N. W. wind produces the greatest cold, a or W. or E. the greatest heat[33].”
“Madrid, lat. 40° 25′, long. 3° 20′ E.
The usual heat in summer is said to be from 75° to 85°; even at night it seldom falls below 70°; the mean height of the barometer is 27,96. It seems to be about 1900 feet above the level of the sea[34].”
The above accounts are extracted from Mr. Kirwan's useful and elaborate estimate of the temperature of different latitudes.
The history which has been given of the climate of Pennsylvania, is confined chiefly to the country on the east side of the Allegany mountain. On the west side of this mountain, the climate differs materially from that of the south-eastern parts of the state in the temperature of the air, in the effects of the winds upon the weather, and in the quantity of rain and snow which falls every year. The winter seldom breaks up on the mountains before the 25th of March. A fall of snow was once perceived upon it, which measured an inch and a half, on the 11th day of June. The trees which grow upon it are small, and Indian corn is with difficulty brought to maturity, even at the foot of the east side of it. The south-west winds on the west side of the mountain are accompanied by cold and rain. The soil is rich, consisting of near a foot, in many places, of black mould. The roads in this country are muddy in winter, but seldom dusty in summer. The arrangement of strata of the earth on the west side, differs materially from their arrangement on the east side the mountain. “The country (says Mr. Rittenhouse, in a letter to a friend in Philadelphia[35]), when viewed from the western ridge of the Allegany, appears to be one vast extended plain. All the various strata of stone seem to lie undisturbed in the situation in which they were first formed, and the layers of stone, sand, clay, and coal, are nearly horizontal.”
The temperature of the air on the west is seldom so hot, or so cold, as on the east side of the mountain. By comparing the state of a thermometer examined by Dr. Bedford at Pittsburg, 284 miles from Philadelphia, it appears that the weather was not so cold by twelve degrees in that town, as it was in Philadelphia, on the 5th of February, 1788.