the air's being at the freezing point. White frosts are frequent when the thermometer is at 47°, have killed young plants of Indian corn at 48°, and have been known at 54°. Black frost, and even ice, have been produced at 380, which is 6 degrees above the freezing point. That other circumstances must be combined with this cold to produce frost, is evident from this also, on the higher parts of mountains, where it is absolutely colder than in the plains on which they stand, frosts do not appear so early by a considerable space of time in autumn, and go off sooner in the spring, than in the plains. I have known frosts so severe as to kill the hickory trees round about Monticello, and yet not injure the tender fruit blossoms then in bloom on the top and higher parts of the mountain; and in the course of forty years, during which it had been settled, there have been but two instances of a general loss of fruit on it; while in the circumjacent country, the fruit has escaped but twice in the last seven years. The plants of tobacco, which grow from the roots of those which have been cut off in the summer, are frequently green here at Christmas. This privilege against the frost is undoubtedly combined with the want of dew on the mountains. That the dew is very rare on their higher parts, I may say with certainty, from twelve years' observations, having scarcely ever, during that time, seen an unequivocal proof of its existence on them at all during summer. Severe frosts in the depth of winter prove that the region of dews extends higher in that season than the tops of the mountains; but certainly, in the summer season, the vapors, by the time they attain that height, are so attenuated as not to subside and form a dew when the sun retires.

The weavil has not yet ascended the high mountains. A more satisfactory estimate of our climate to some, may perhaps be formed, by noting the plants which grow here, subject, however, to be killed by our severest colds. These are the fig, pomegranate, artichoke, and European walnut. In mild winters, lettuce and endive require no shelter; but, generally, they need a slight covering. I do not know that the want of long moss, reed, myrtle, swamp laurel, holly, and cypress, in the upper country proceeds from a greater degree of cold, nor that they

were ever killed with any degree of cold, nor that they were ever killed with any degree of cold in the lower country. The aloe lived in Williamsburg, in the open air, through the severe winter of 1779, 1780.

A change in our climate, however, is taking place very sensibly. Both heats and colds are become much more moderate within the memory even of the middle-aged. Snows are less frequent and less deep. They do not often lie, below the mountains, more than one, two, or three days, and very rarely a week. They are remembered to have been formerly frequent, deep, and of long continuance. The elderly inform me, the earth used to be covered with snow about three months in every year. The rivers, which then seldom failed to freeze over in the course of the winter, scarcely ever do so now. This change has produced an unfortunate fluctuation between heat and cold, in the spring of the year, which is very fatal to fruits. From the year 1741 to 1769, an interval of twenty-eight years, there was no instance of fruit killed by the frost in the neighborhood of Monticello. An intense cold, produced by constant snows, kept the buds locked up till the sun could obtain, in the spring of the year, so fixed an ascendency as to dissolve those snows, and protect the buds, during their development, from every danger of returning cold. The accumulated snows of the winter remaining to be dissolved all together in the spring, produced those overflowings. of our rivers, so frequent then, and so rare now.

Having had occasion to mention the particular situation of Monticello for other purposes, I will just take notice that its elevation affords an opportunity of seeing a phenomenon which is rare at land, though frequent at sea. The seamen call it looming. Philosophy is as yet in the rear of the seamen, for so far from having accounted for it, she has not given it a name. Its principal effect is to make distant objects appear larger, in opposition to the general law of vision, by which they are diminished. I knew an instance, at Yorktown, from whence the water prospect eastwardly is without termination, wherein a canoe with three men, at a great distance was taken for a ship with its three masts. I am little acquainted with the phenom

enon as it shows itself at sea; but at Monticello it is familiar. There is a solitary mountain about forty miles off in the South, whose natural shape, as presented to view there, is a regular cone; but by the effect of looming, it sometimes subsides almost totally in the horizon; sometimes it rises more acute and more elevated; sometimes it is hemispherical; and sometimes its sides are perpendicular, its top flat, and as broad as its base. In short, it assumes at times the most whimsical shapes, and all these perhaps successively in the same morning. The blue ridge of mountains comes into view, in the north-east, at about one hundred miles distance, and approaching in a direct line, passes by within twenty miles, and goes off to the south-west. This phenomenon begins to show itself on these mountains, at about fifty miles distance, and continues beyond that as far as they are seen. I remark no particular state, either in the weight, moisture, or heat of the atmosphere, necessary to produce this. only constant circumstances are its appearance in the morning only, and on objects at least forty or fifty miles distant. In this latter circumstance, if not in both, it differs from the looming on the water.

The

Refraction will not account for the metamorphosis. That only changes the proportions of length and breadth, base and altitude, preserving the general outlines. Thus it may make a circle appear elliptical, raise or depress a cone, but by none of its laws, as yet developed, will it make a circle appear a square, or a cone a sphere.

QUERY VIII.

The number of its inhabitants?

The following table shows the number of persons imported for the establishment of our colony in its infant state, and the census of inhabitants at different periods, extracted from our his torians and public records, as particularly as I have had opportunities and leisure to examine them. Successive lines in the

I have

same year show successive periods of time in that year. stated the census in two different columns, the whole inhabitants having been sometimes numbered, and sometimes the tythes only. This term, with us, includes the free males above sixteen years of age, and slaves above that age of both sexes. A further examination of our records would render this history of our population much more satisfactory and perfect, by furnishing a greater number of intermediate terms. These, however, which are here stated will enable us to calculate, with a considerable degree of precision, the rate at which we have increased. During the infancy of the colony, while numbers were small, wars, importations, and other accidental circumstances render the progression fluctuating and irregular. By the year 1654, however, it becomes tolerably uniform, importations having in a great measure ceased from the dissolution of the company, and the inhabitants become too numerous to be sensibly affected by Indian wars. Beginning at that period, therefore, we find that from thence to the year 1772, our tythes had increased from 7,209 to 153,000. The whole term being of one hundred and eighteen

years, yields a duplication once in every twenty-seven and a quarter years. The intermediate enumerations taken in 1700, 1748, and 1759, furnish proofs of the uniformity of this progression. Should this rate of increase continue, we shall have between six and seven millions of inhabitants within ninetyfive years. If we suppose our country to be bounded, at some future day, by the meridian of the mouth of the Great Kanhaway, (within which it has been before conjectured, are 64,461 square miles) there will then be one hundred inhabitants for every square mile, which is nearly the state of population in the British Islands.

Here I will beg leave to propose a doubt. The present desire of America is to produce rapid population by as great importations of foreigners as possible. But is this founded in good policy? The advantage proposed is the multiplication of numbers. Now let us suppose (for example only) that, in this state, we could double our numbers in one year by the importation of foreigners; and this is a greater accession than the most sanguine advocate for emigration has a right to expect. Then I say, beginning with a double stock, we shall attain any given degree of population only twenty-seven years, and three months sooner than if we proceed on our single stock. If we propose four millions and a half as a competent population for this State, we should be fifty-four and a half years attaining it, could we at once double our numbers; and eighty-one and three quarter years, if we rely on natural propagation, as may be seen by the following tablet:

In the first column are stated periods of twenty-seven and a quarter years; in the second are our numbers at each period, as they will be if we proceed on our actual stock; and in the third are what they would be, at the same periods, were we to set out