JEFFERSON ON CLIMATE

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JEFFERSON ON CLIMATE

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SMITHSONIAN MAGAZINE

America’s First Great Global Warming Debate - Thomas Jefferson and Noah Webster argue over conventional wisdom that lasted thousands of years


By Joshua Kendall, smithsonianmag.com

July 14, 2011

As the tumultuous century was drawing to a close, the conservative Yale grad challenged the sitting vice president’s ideas about global warming.

The vice president, a cerebral Southerner, was planning his own run for the presidency, and the fiery Connecticut native was eager to denounce the opposition party.

The date was 1799, not 1999 — and the opposing voices in America’s first great debate about the link between human activity and rising temperature readings were not Al Gore and George W. Bush, but Thomas Jefferson and Noah Webster.

As a gentleman farmer in Virginia, Jefferson had long been obsessed with the weather; in fact, on July 1, 1776, just as he was finishing his work on the Declaration of Independence, he began keeping a temperature diary.

Jefferson would take two readings a day for the next 50 years.

He would also crunch the numbers every which way, calculating various averages such as the mean temperature each month and each year.

In his 1787 book, Notes on the State of Virginia, Jefferson launched into a discussion of the climate of both his home state and America as a whole.

Near the end of a brief chapter addressing wind currents, rain and temperature, he presented a series of tentative conclusions: “A change in our climate…is taking place very sensibly."

"Both heats and colds are become much more moderate within the memory of the middle-aged."

"Snows are less frequent and less deep…."

"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.”

Concerned about the destructive effects of this warming trend, Jefferson noted how “an unfortunate fluctuation between heat and cold” in the spring has been “very fatal to fruits.”

Jefferson was affirming the long-standing conventional wisdom of the day.

For more than two millennia, people had lamented that deforestation had resulted in rising temperatures.


A slew of prominent writers, from the great ancient naturalists Theophrastus and Pliny the Elder to such Enlightenment heavyweights as the Comte de Buffon and David Hume, had alluded to Europe’s warming trend.

A contemporary authority, Samuel Williams, the author of a 1794 magnum opus, The Natural and Civil History of Vermont, had studied temperature readings at several points in the 18th century from his home state and half a dozen other locales throughout North America, including South Carolina, Maryland and Quebec.

Citing this empirical data, Williams claimed that the leveling of trees and the clearing of lands had caused the earth to become warmer and drier.

“[Climate] change…instead of being so slow and gradual, as to be a matter of doubt,” he argued, “is so rapid and constant, that it is the subject of common observation and experience."

"It has been observed in every part of the United States; but is most of all sensible and apparent in a new country, which is suddenly changing from a state of vast uncultivated wilderness, to that of numerous settlements.”

This opinion had been uttered for so long that it was widely accepted as a given — until Webster.

Today Webster is best known as the author of the American Dictionary of the English Language (1828), but his “great book” was actually his retirement project.

He was a pioneering journalist who edited American Minerva, New York City’s first daily newspaper in the 1790s, and he weighed in on the major public policy issues of the day, cranking out essays on behalf of the Constitution, a 700-page treatise on epidemics and a condemnation of slavery.

He would also serve in the state legislature of both Connecticut and Massachusetts.

Webster disputed the “popular opinion that the temperature of the winter season, in northern latitudes, has suffered a material change” in a speech before the newly established Connecticut Academy of Arts and Sciences in 1799.

Several years later, Webster delivered a second address on the topic.

The two speeches were published together in 1810 under the title “On the Supposed Change of in the Temperature of Winter.”

With the thermometer still a relatively recent invention — the Polish inventor Daniel Fahrenheit didn’t develop his eponymous scale until 1724 — conclusions about weather patterns before the mid-18th century were based largely on anecdotes.

In the first two-thirds of his 1799 speech, Webster attacked Williams, a pastor who helped found the University of Vermont, for his faulty interpretations of literary texts such as the Bible and Virgil’s Georgics.

Challenging Williams’ assumption — derived from his close examination of the Book of Job — that winters in Palestine were no longer as cold as they used to be, Webster declared, “I am really surprised to observe on what a slight foundation, a divine and philosopher has erected this theory.”

But Webster, while acknowledging that the Bible may well not have been “a series of facts,” tried to spin the weather imagery in ancient texts his own way.

Citing passages from Horace and Pliny, Webster asserted that “we then have the data to ascertain the ancient climate of Italy with great precision.”

To settle the scientific debate, Webster offered more than just literary exegesis.

In examining “the cold of American winters,” Webster focused on the numbers — and his opponents’ lack of hard data (Jefferson recorded his own temperature readings in a private diary).

“Mr. Jefferson,” Webster stated, “seems to have no authority for his opinions but the observations of elderly and middle-aged people.”

Webster saved most of his ammunition for Williams, who had written the more extensive brief, replete with an array of temperature readings.

Williams’ central contention, that America’s temperature had risen by 10 or 12 degrees in the prior century and a half, Webster asserted, just doesn’t make any sense.

“The mean temperature of Vermont,” he writes, “is now 43 degrees…"

"If we suppose the winter only to have changed, and deduct one half the supposed abatement, still the result forbids us to believe the hypothesis."

"If we suppose the heat of summer to have lessened in the same proportion…the summers formerly must have been intolerable; no animal could have subsisted under ten degrees of heat beyond our present summer temperature."

"On whichever side we turn our eyes, we meet with insurmountable difficulties.”

Webster concluded by rejecting the crude warming theory of Jefferson and Williams in favor of a more subtle rendering of the data.

The conversion of forests to fields, he acknowledged, has led to some microclimatic changes — namely, more windiness and more variation in winter conditions.

But while snow doesn’t stay on the ground as long, that doesn’t necessarily mean the country as a whole gets less snowfall each winter: “We have, in the cultivated districts, deep snow today, and none tomorrow; but the same quantity of snow falling in the woods, lies there till spring…."

"This will explain all the appearances of the seasons without resorting to the unphilosophical hypothesis of a general increase in heat.”

Webster’s words essentially ended the controversy.

While Jefferson continued to compile and crunch temperature data after his retirement from the presidency, he never again made the case for global warming.

Neither did Williams, who died a few years after the publication of Webster’s article.

Webster’s position was considered unimpeachable.

In 1850, the acclaimed German naturalist Alexander von Humboldt declared that “statements frequently advanced, although unsupported by measurements, that…the destruction of many forests on both sides of the Alleghenys has rendered the climate more equable…are now generally discredited.”

And there the matter rested until the second half of the 20th century, when scientists began to understand the impact of greenhouse gases on the environment.

The second great global warming debate poses a different set of scientific questions from those raised in the late 18th century, and this time the science clearly supports the idea that human activity (including clearing and burning forests) can increase temperatures.

But it is Webster’s papers, with their careful analysis of the data, that have stood the test of time.

Kenneth Thompson, a modern environmental scientist from the University of California at Davis, praises “the force and erudition” of Webster’s arguments and labels his contribution to climatology “a tour de force.”

Joshua Kendall is the author of The Forgotten Founding Father: Noah Webster’s Obsession and the Creation of an American Culture (Putnam, 2011).

https://www.smithsonianmag.com/history/ ... -31911494/
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Re: JEFFERSON ON CLIMATE

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Thomas Jefferson and the American climate and THE HISTORY OF AMERICAN WEATHER

David M. Ludlum Editor of WEATHERWISE

Vol. 47, No. 12, December 1966

Bulletin American Meteorological Society

While putting the finishing touches to the draft of the Declaration of Independence at Philadelphia on 1 July 1776, Thomas Jefferson purchased his first thermometer and a week later procured a barometer.

Thereafter, for half a century these were his close companions whether at home at Monticello, in the governor's chair at Williamsburg, as ambassador to France abroad, in the honored place of secretary of state, vice president, or president, Jefferson took the readings of his instruments whenever the occasion permitted and recorded them in his "Weather Memorandum Book."

A wish for a more precise definition of the climatic characteristics of first his native Virginia and later the entire United States was always uppermost in his mind as shown by the frequent mention of the subject in his voluminous correspondence.

Soon after his return to his beloved Monticello near Charlottesville in west-central Virginia, Jefferson entered into an exchange of data with Rev. James Madison, the science-oriented president of William and Mary College at Williamsburg on the tidewater.

These simultaneous observations covered a good part of 1777 and 1778 until the fortunes of war put an end to this early attempt to compare climate differences.

Jefferson employed these observations in 1781 when composing his celebrated Notes on the State of Virginia, generally conceded to be the most valuable book of a scientific nature to be produced by an American up to that time.

At the conclusion of the war, he secured the only available thermometer in Philadelphia and sent it to Isaac Zane in the Ohio Valley country so that some knowledge of the climate west of the mountains might be determined with scientific precision.

He then proposed that every county in Virginia be supplied with a barometer and thermometer, but the difficulty of obtaining such items in the turmoil-torn, youthful republic prevented the realization of this far-seeing plan.

Jefferson had little doubt about the salubrity of the climate of his native Virginia.

When experiencing the rigor and surprises of a New England spring in 1791, he wrote his daughter: "On the whole, I find nothing anywhere else, in point of climate which Virginia need envy to any part of the world. . . .

When we consider how much climate contributes to the happiness of our conditions, by the fine sensation it excites, and the productions it is parent of, we have reason to value highly the accident of birth in such a one as that of Virginia."


Again, when writing in 1797, Jefferson declared: ". . indeed my experiences in different parts of America convinces me that these mountains [the Blue Ridge of Virginia] are the Eden of the U. S. for soil, climate, navigation and health."

Jefferson served as consultant to all who wished to learn about the climate, the ways of the weather, and the phenological pattern of the new American States.

One of these was Constantin Francois de Chasseboeuf, Comte to Volney, who publicized his conversations with Jefferson on this subject in a widely circulated volume, and then for many years was considered an authority on the American climate, though both Jefferson and Volney shared an early misconception as to the relative coldness of the country east and west of the Appalachian Mountains.

When in the presidency, Jefferson sent the explorers Lewis and Clark into the Northwest and the scientist William Dunbar into the Southwest with a study of climate conditions high on the agenda of the two expeditions.

Our knowledge of the early climate of the present District of Columbia area is due to the meteorological activities of the first and third presidents of the United States.

George Washington at his Mt. Vernon plantation, within sight of the present capitol, commenced "An account of the weather" in 1767 and continued with frequent breaks until his death in December 1799, his last entry being penned the day before he passed away.

Thomas Jefferson took up residence in the newly established seat of government some 15 months later.

He soon commenced the thermometric and snowfall measurements which now permit one to make a judgment as to the type of climate enjoyed by the first federal residents of the Potomac village from 1802 to 1809.

These accomplishments for a busy official would have been enough to secure Jefferson a high position among American pioneer climatologists.

But his most significant contribution lay ahead in his years of retirement when in March of 1809 at the age of sixty-six he left the political battle arena and returned to the fields of agriculture at Monticello.

Here are his words concerning the following years:

1817, January.

Having been stationary at home since 1809, with opportunity and leisure to keep a meteorological diary, with a good degree of exactness, this had been done: and, extracting from it a term of seven years complete, to wit from January 1, 1810, to December 31, 1816, I proceed to analyze it in the various ways, and to reduce the general results, which are of principal effect in the estimation of climate.

The observations, three thousand nine hundred and five, in the whole, were taken before sunrise of every day; and again between three and four o'clock P.M.

Jefferson's instruments included a thermometer, barometer, rain gage, and wind vane.

He had a hygrometer at Washington, but mention of this does not appear now.

The twice daily observations were reduced to means and totals, and tables constructed for each month of the seven years.

He summarized these in a "Memorandum on Climate."

In addition, Jefferson kept close watch on the phenological aspects of the local climate.

He summarized these in 1818 for Professor Bigelow of Harvard College who consolidated them with a report on a national scale he was making.

The "Memorandum on Climate" was first published in 1829 in the Virginia Literary Museum and Journal of Belles Lettres, Art, Sciences, &c.

A more recent re-publication in Edwin Morris Betts, Thomas Jefferson's Garden Book 1766-1824 (Phila., American Philosophical Society, 1944) made the study available in many libraries of the country.

Jefferson, as had Washington, faithfully pursued his weather observations well into his last illness.

In June 1826 there were 10 rainfall entries in the "Weather Memorandum Book," the last being on 29 June, just six days before his death on 4 July 1826, fifty years to the day since he signed the illustrious document which stands as the greatest contribution of an American to mankind.
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Re: JEFFERSON ON CLIMATE

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From Notes on the State of Virginia by Thomas Jefferson

QUERY VII - A notice of all what can increase the progress of Human Knowledge?

Under the latitude of this query, I will presume it not improper nor unacceptable to furnish some data for estimating the climate of Virginia.

Journals of observations on the quantity of rain, and degree of heat, being lengthy, confused, and too minute to produce general and distinct ideas, I have taken five years’ observations, to wit, from 1772 to 1777, made in Williamsburg and its neighborhood, have reduced them to an average for every month in the year, and stated those averages in the following table, adding an Analytical view of the winds during the same period.


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 337.

At 73 of these, the wind was from the North; 47 from the Northeast, &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 3,698, it will be observed that 611 of them were from the North, 558 from the North-east, &c.

Though by this table it appears we have on an average 47 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 Alleghaney, which is the highest land between the ocean and the Missisipi.

From thence, descending in the same latitude to the Missisipi, 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 Missisipi, as far as the latitude of 37°, and reeds as far as 38°.

Perroquets even winter on the Sioto, 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 Chesapeak bay, and at the Alleghaney, 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 6⅛°. of Farenheit’s thermometer.

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Re: JEFFERSON ON CLIMATE

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From Notes on the State of Virginia by Thomas Jefferson, continued …

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 1/37 of its whole weight.

It should be observed, however, that the hill of Monticello is of 500 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 Alleghaney, may be considered as furnishing the best average of the temperature of our climate.

Williamsburgh 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, 421 from the preceding table of winds at Williamsburg, taking them proportionably from every point:

By this it may be seen that the South-west wind prevails equally at both places; that the Northeast 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 vapour, 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 20 to 30 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 countries, 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.

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Re: JEFFERSON ON CLIMATE

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From Notes on the State of Virginia by Thomas Jefferson, continued …

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 were 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.

Cotemporary 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 Farenheit’s thermometer has been known to descend from 92°. to 47°. in thirteen hours.


It was taken for granted, that the preceding table of averaged heat will not give a false idea on this subject, as it proposes to state only the ordinary heat and cold of each month, and not those which are extraordinary.

At Williamsburg, in August 1766, the mercury in Farenheit’s thermometer was at 98°. corresponding with 29⅓ of Reaumur.

At the same place in January 1780, it was 6°. corresponding with 11½ below 0. of Reaumur.

I believe these may be considered to be nearly the extremes of heat and cold in that part of the country.

The latter may most certainly, as that time York river, at Yorktown, was frozen over, so that people walked across it; a circumstance which proves it to have been colder than the winter of 1740, 1741, usually called the cold winter, when York river did not freeze over at that place.

In the same season of 1780, Chesapeak bay was solid, from its head to the mouth of the Patowmac.

At Annapolis, where it is 5¼ miles over between the nearest points of land, the ice was from five to seven inches thick quite across, so that loaded carriages went over on it.


Those, our extremes of heat and cold, of 6°. and 98°. were indeed very distressing to us, and were thought to put the extent of the human constitution to considerable trial.

Yet a Siberian would have considered them as scarcely a sensible variation.

At Jenniseitz in that country, in latitude 58°.27′. we are told that the cold in 1735 sunk the mercury by Farenheit’s scale to 126°. below nothing; and the inhabitants of the same country use stove rooms two or three times a week, in which they stay two hours at a time, the atmosphere of which raises the mercury to 135°. above nothing.

Late experiments shew that the human body will exist in rooms heated to 140°. of Reaumur, equal to 347°. of Farenheit’s, and 135°. above boiling water.

The hottest point of the twenty four hours is about four o’clock, P. M., and the dawn of day the coldest.

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Re: JEFFERSON ON CLIMATE

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From Notes on the State of Virginia by Thomas Jefferson, continued …

The access of frost in autumn, and its recess in the spring, do not seem to depend merely on the degree of cold; much less on 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 38½°. which is 6½ 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 40 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 12 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 become 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.

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Re: JEFFERSON ON CLIMATE

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From Notes on the State of Virginia by Thomas Jefferson, concluded …

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 ascendancy 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 phænomenon 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 phenomenon as it shows itself at sea; but at Monticello it is familiar.

There is a solitary mountain about 40 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 100 miles distance, and approaching in a direct line, passes by within 20 miles, and goes off to the South-West.

This phænomenon begins to shew 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.

The only constant circumstances are its appearance in the morning only, and on objects at least 40 or 50 miles distant.

In this latter circumstance, if not in both, it differs from the looming on the water.

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.
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