The rains of every month, (as of January, for instance,) through the whole period of years, were added separately, and an average drawn from them. The coolest and warmest point of the same day in each year of the period, were added separately, and an average of the greatest cold and greatest heat of that day was formed. From the averages of every day in the month, a general average was formed. The point from which the wind blew, was observed two or three times in every day. These observations, in the month of January, for instance, through the whole period, amounted to three hundred and thirty-seven. At seventy-three of these, the wind was from the north; forty-seven from the north-east, &c. So that it will be easy to see in what proportion each wind usually prevails in each month; or, taking the whole year, the total of observations through the whole period having been three thousand six hundred and ninety-eight, it will be observed that six hundred and eleven of them were from the north, five hundred and fifty-eight from the north-east, &c.

Fall of rain, etc., in inches.Least and greatest daily heat, by Fahrenheit's thermometer. WINDS.
N. N.E. E.S.E. S.S.W. W.N.W.Total.
Jan. 3.19238½ to 44 7347 3210 1178 4046 337
Feb. 2.04941 .. 47½6152 2411 463 3031 276
March 3.95 48 .. 54½4944 3828 1483 2933 318
April 3.68 56 .. 62½3544 5419 958 1820 257
May 2.87163 .. 70½2736 6223 774 3220 281
June 3.75171½ .. 78¼2234 4324 1381 2525 267
July 4.49777 .. 82½4144 7515 795 3219 328
August9.15376¼ .. 81 4352 4030 9103 2730 334
Sept. 4.76169½ .. 74¼7060 5118 1081 1837 345
Oct. 3.63361¼ .. 66½5277 6415 656 2334 327
Nov. 2.61747¾ .. 53½7421 2014 963 3558 294
Dec. 2.87743 .. 48¾ 64 37 18 16 10 91 42 56 334
Total.47.038 8 A.M. to 4 P.M.611548 521223 109926 351409 3,698

Though by this table it appears we have on an average forty-seven inches of rain annually, which is considerably more than usually falls in Europe, yet from the information I have collected, I suppose we have a much greater proportion of sunshine here than there. Perhaps it will be found, there are twice as many cloudy days in the middle parts of Europe, as in the United States of America. I mention the middle parts of Europe, because my information does not extend to its northern or southern parts.

In an extensive country, it will of course be expected that the climate is not the same in all its parts. It is remarkable, that proceeding on the same parallel of latitude westwardly, the climate becomes colder in like manner as when you proceed northwardly. This continues to be the case till you attain the summit of the Alleghany, which is the highest land between the ocean and the Mississippi. From thence, descending in the same latitude to the Mississippi, the change reverses; and, if we may believe travellers, it becomes warmer there than it is in the same latitude on the sea-side. Their testimony is strengthened by the vegetables and animals which subsist and multiply there naturally, and do not on the sea-coast. Thus Catalpas grow spontaneously on the Mississippi, as far as the latitude of 37°, and reeds as far as 38°. Parroquets even winter on the Scioto, in the 39th degree of latitude. In the summer of 1779, when the thermometer was at 90° at Monticello, and 96° at Williamsburg, it was 110° at Kaskaskia. Perhaps the mountain, which overhangs this village on the north side, may, by its reflection, have contributed somewhat to produce this heat. The difference of temperature of the air at the sea-coast, or on the Chesapeake bay, and at the Alleghany, has not been ascertained; but contemporary observations, made at Williamsburg, or in its neighborhood, and at Monticello, which is on the most eastern ridge of the mountains, called the South-West, where they are intersected by the Rivanna, have furnished a ratio by which that difference may in some degree be conjectured. These observations make the difference between Williamsburg and the nearest mountains, at the position before mentioned, to be on an average 6⅓° of Fahrenheit's thermometer. Some allowance, however, is to be made for the difference of latitude between these two places, the latter being 38° 8' 17", which is 52' 22" north of the former. By contemporary observations of between five and six weeks, the averaged and almost unvaried difference of the height of mercury in the barometer, at those two places, was .784 of an inch, the atmosphere at Monticello being so much the lightest, that is to say, about one-thirty-seventh of its whole weight. It should be observed, however, that the hill of Monticello is of five hundred feet perpendicular height above the river which washes its base. This position being nearly central between our northern and southern boundaries, and between the bay and Alleghany, may be considered as furnishing the best average of the temperature of our climate. Williamsburg is much too near the south-eastern corner to give a fair idea of our general temperature.

But a more remarkable difference is in the winds which prevail in the different parts of the country. The following table exhibits a comparative view of the winds prevailing at Williamsburg, and at Monticello. It is formed by reducing nine months' observations at Monticello to four principal points, to wit, the north-east, south-east, south-west, and north-west; these points being perpendicular to, or parallel with our coast, mountains, and rivers; and by reducing in like manner, an equal number of observations, to wit, four hundred and twenty-one from the preceding table of winds at Williamsburg, taking them proportionably from every point:

N.E.S.E.S.W.N.W.Total.
Williamsburg12761132101421
Monticello3291126172421

By this it may be seen that the south-west wind prevails equally at both places; that the north-east is, next to this, the principal wind towards the sea-coast, and the north-west is the predominant wind at the mountains. The difference between these two winds to sensation, and in fact, is very great. The north-east is loaded with vapor, insomuch, that the salt-makers have found that their crystals would not shoot while that blows; it brings a distressing chill, and is heavy and oppressive to the spirits. The north-west is dry, cooling, elastic, and animating. The eastern and south-eastern breezes come on generally in the afternoon. They have advanced into the country very sensibly within the memory of people now living. They formerly did not penetrate far above Williamsburg. They are now frequent at Richmond, and every now and then reach the mountains. They deposit most of their moisture, however, before they get that far. As the lands become more cleared, it is probable they will extend still further westward.

Going out into the open air, in the temperate, and warm months of the year, we often meet with bodies of warm air, which passing by us in two or three seconds, do not afford time to the most sensible thermometer to seize their temperature. Judging from my feelings only, I think they approach the ordinary heat of the human body. Some of them, perhaps, go a little beyond it. They are of about twenty to thirty feet diameter horizontally. Of their height we have no experience, but probably they are globular volumes wafted or rolled along with the wind. But whence taken, where found, or how generated? They are not to be ascribed to volcanos, because we have none. They do not happen in the winter when the farmers kindle large fires in clearing up their grounds. They are not confined to the spring season, when we have fires which traverse whole counties, consuming the leaves which have fallen from the trees. And they are too frequent and general to be ascribed to accidental fires. I am persuaded their cause must be sought for in the atmosphere itself, to aid us in which I know but of these constant circumstances: a dry air; a temperature as warm, at least, as that of the spring or autumn; and a moderate current of wind. They are most frequent about sun-set; rare in the middle parts of the day; and I do not recollect having ever met with them in the morning.

The variation in the weight of our atmosphere, as indicated by the barometer, is not equal to two inches of mercury. During twelve months' observation at Williamsburg, the extremes 29 and 30.86 inches, the difference being 1.86 of an inch; and in nine months, during which the height of the mercury was noted at Monticello, the extremes were 28.48 and 29.69 inches, the variation being 1.21 of an inch. A gentleman, who has observed his barometer many years, assures me it has never varied two inches. Contemporary observations made at Monticello and Williamsburg, proved the variations in the weight of air to be simultaneous and corresponding in these two places.

Our changes from heat to cold, and cold to heat, are very sudden and great. The mercury in Fahrenheit's thermometer has been known to descend from 92° to 47° in thirteen hours.