Why Did Jefferson Do This?
Jefferson provided little explanation of his reasons for keeping the weather records. In his encouragement to James Madison in 1784, he stated only that “It will be an amusement to you and may become useful.” But Jefferson kept at it, off and on, for half a century. Why? Some motivations that might be suggested are:
Jefferson was a “Renaissance Man” who investigated all areas of intellectual inquiry. There is some basis to this as a reason for Jefferson’s attention to weather, but with limitations. Jefferson was proficient at architecture; he excavated and studied the stratigraphy of an ancient mound; he wrote a paper describing fossil remains of an ancient ground sloth; and he used mathematics to design a plowshare. This Jefferson-as-polymath is imagined in Cornelius Tiebout’s 1801 engraving, which depicted the newly elected president of the United States with a globe, an electrostatic generator, and a bust of Benjamin Franklin all close at hand along with the Declaration of Independence. Yet for his own time and attention, Jefferson dismissed theory that was unrelated to practical problems and shunned the pursuit of knowledge for its own sake. In a 1799 letter responding to a young man who had asked him what subjects were important to study, he listed several areas of science, including natural philosophy (what we would call natural sciences), but nothing specifically relating to what we would term meteorology. For Jefferson, there needed to be a reason for any scientific investigation.
He relied on agriculture for his income and farmers are closely dependent on the weather. There is likely some basis for this as a reason for his weather observation. He made several notations in the records relating to crops such as tobacco and corn, and gave particular attention to garden produce. There is no clear picture, however, of how he might have tried to use his assemblage of quantified data to make decisions about planting or harvesting. No one had worked out how to turn meteorological data into reliable predictions of the weather. And a big question would be why, if his primary motivation for keeping his weather records was to help him manage his Virginia plantations, he made observations in Paris for four and a half years in the 1780s.
He was a member of networks that encouraged the collection and sharing of meteorological information. This was likely one of his stronger motivations. When Jefferson attended the College of William and Mary in Williamsburg in the early 1760s, his most influential mentor on the faculty was William Small. Educated at the University of Aberdeen in his native Scotland, Small taught mathematics and natural philosophy (natural science) at the college and trained Jefferson in quantitative and systematic approaches to science. Small introduced the promising student to George Wythe, who became Jefferson’s law teacher, and Small and Wythe brought Jefferson into the circle of Francis Fauquier, the British colonial governor in Virginia. Dinners at the residence of the erudite Fauquier were like intellectual salons, as Jefferson later recalled. Among the governor’s interests was the weather: during the time when the young Jefferson became part of Fauquier’s talented group of friends, the governor was keeping a weather diary in which he recorded the temperature, direction of the wind, and general conditions twice a day. Fauquier was also a fellow of the Royal Society of London, and information he sent back to England about “an extraordinary Storm of Hail in Virginia” appeared in the society’s published Transactions. Fauquier provided a model for the incorporation of meteorological observations in an informed person’s intellectual repertoire, and the group of which he was the center, and which included Jefferson’s mentors Small and Wythe, furnished an example of a network for the exchange of knowledge about topics such as weather and climate.
From those origins in Williamsburg, Jefferson went on to become himself a key figure in networks of people interested in science and in collecting information about weather and climate. His close friend from college, John Page, maintained and shared the contents of a weather journal. In addition to advising his friend and political ally James Madison in starting a weather diary, Jefferson exchanged information about weather observations with David Rittenhouse, the largely self-taught astronomer, mathematician, clockmaker, and builder of scientific apparatus who later succeeded Benjamin Franklin as president of the American Philosophical Society; with the Reverend James Madison, an Episcopal clergyman and second cousin of Jefferson’s friend, who was a successor to William Small in teaching natural sciences at the College of William and Mary; with the French philosopher and writer Constantin François de Chassebœuf (the Comte de Volney); with William Dunbar, an educated Scots-born plantation owner and scientist in the lower Mississippi Valley; and with Hugh Williamson, a respected amateur scientist in North Carolina. And he brought his son-in-law Thomas Mann Randolph, Jr., into the web of connections, asking Randolph to record temperatures in Virginia when Jefferson was in other locations in the 1790s.
He had a strong interest in the geography and climate of America. Jefferson believed that Europeans tended to slight or dismiss America. His long-running contention with the writings of the Comte de Buffon about comparisons of native animal species, indigenous peoples, and other topics is well known. Too little was understood about the geography, natural history, and climate of North America, Jefferson thought, and he wanted to expand the knowledge base. To Giovanni Fabbroni, then in Paris, Jefferson wrote in 1778: “Tho’ much of my time is employed in the councils of America I have yet a little leisure to indulge my fondness for philosophical studies. I could wish to correspond with you on subjects of that kind. It might not be unacceptable to you to be informed for instance of the true power of our climate as discoverable from the Thermometer, from the force and direction of the winds, the quantity of rain, the plants which grow without shelter in the winter &c. On the other hand we should be much pleased with cotemporary observations on the same particulars in your country, which will give us a comparative view of the two climates.”
He was moreover quite interested in relationships between human populations and the places where they lived. Weather and climate were essential parts of this inquiry. Jefferson wrote Notes on the State of Virginia in response to a set of questions that a French consul sent to each of the states. None of the questions was about climate. Yet to Query VII, asking for “A notice of all what can increase the progress of human knowledge?” Jefferson responded: “Under the latitude of this query, I will presume it not improper nor unacceptable to furnish some data for estimating the climate of Virginia.” In that chapter, he analyzed five years of meteorological data from Williamsburg (not collected by him) and discussed differences in temperature between the seacoast and the Mississippi Valley and among different parts of Virginia, winds at Williamsburg and Monticello, effects of elevation on barometric pressure, and winter cold as a limiting factor in the ranges of plants. He was keenly interested in comparative questions about climate and weather. When he had to be away from Virginia on official business, he asked Randolph, who was trained as a physician, to keep a weather diary “that we may have a comparative view of the climates” of their respective locations.
Early in 1801, when Jefferson received meteorological data from Quebec soon after receiving similar information from the Natchez region on the lower Mississippi River, he immediately compared the figures and “was struck with the comparison” between the lowest temperature in each register (32° below 0° Fahrenheit at Quebec versus slightly below 20° near Natchez). “I have often wondered that any human being should live in a cold country who can find room in a warm one,” he wrote to William Dunbar, who had provided the Natchez information. As he laid out in a detailed letter to the Marquis de Chastellux in 1785, Jefferson believed that climate was a dominant factor in shaping the character of people in the southern and northern regions of the United States, with people from the middle states displaying a blend of the traits. He declared that northerners were “cool,” “sober,” and “laborious” but also “chicaning,” whereas southerners were “fiery,” “Voluptuary,” “indolent,” and “candid.”
For Jefferson, addressing what he perceived to be practical and fundamental questions of climate and geography appears to have been the strongest motive for the collection and exchange of detailed information about weather and climate.
Silvio A. Bedini, Thomas Jefferson: Statesman of Science (New York, 1990), 28-32.
Andrew Burnaby, Travels through the Middle Settlements in North America, in the Years 1759 and 1760; with Observations on the State of the Colonies, 3d ed. (London, 1798), 173-209.
Daniel L. Druckenbrod, Michael E. Mann, David W. Stahle, Malcolm K. Cleaveland, Matthew D. Therrell, and Herman H. Shugart, “Late-Eighteenth-Century Precipitation Reconstructions from James Madison’s Montpelier Plantation,” Bulletin of the American Meteorological Society, 84 (2003), 57-72.
Francis Fauquier, “An Acccount of an Extraordinary Storm of Hail in Virginia,” Philosophical Transactions of the Royal Society, 50 (1757–1758), 746-7.
Thomas Jefferson, Notes on the State of Virginia, ed. William Peden (Chapel Hill, N.C.), 73-81.