Joseoph Priestly correspondence, 1766-1803


Date: 1766-1803 | Size: 1 microfilm_reel(s)


These letters are to Rev. Theophilus Lindsay and Rev. Thomas Belsham pertaining to natural history, science, and theology.

Background note

Joseph Priestley (1733-1804, APS 1785) was a British radical theologian, scientist and political philosopher, who exerted enormous influence in English and American intellectual circles. Priestley is of often credited with the discovery of oxygen. His defense of phlogiston theory and rejection of what came to be known as the Chemical Revolution contributed to his isolation from the scientific community in his later life. His heterodox religious views subjected him to persecutions that eventually compelled him to emigrate to the United States, where he spent the last decade of his life.

Priestley was born in Birstall, Yorkshire, in 1733. His parents were Jonas Priestley, a finisher of cloth, and his wife Mary Swift. He was raised by prosperous relatives who had fallen under the sway of dissenting doctrine. A promising student, he attended local schools where he studied the ancient languages. His guardians intended to prepare the precocious boy for the ministry. As a result of ill health and his unpalatable religious affiliations he was prevented from entering either Oxford or Cambridge, choosing instead to attend the dissenting academy at Daventry.

After receiving his degree in 1755, Priestley discovered that his road into the ministry was hampered by a stutter and, more importantly, his unorthodox views. His call to the Dissenting parish of Needham Market, Suffolk, turned out to be disappointing for both him and his parishioners, many of who were critical of his heterodoxy and therefore refused to attend his services and send their children to be educated by him. In 1758 he moved to another parish, Nantwich, Cheshire, where the congregation proved more accepting of his views as well as his talents as a teacher. Priestley opened a school in which he taught natural philosophy, and he also wrote The Rudiments of English Grammar (1761). By 1761, his reputation as an educator had grown to such an extent that he was offered the position of Professor of Languages at the prestigious Warrington Academy. The next year he was ordained and married Mary Wilkinson, daughter of a Welsh ironmaster. In education as in religion, Priestley's approach was insistently unorthodox. He introduced the study of modern history, law, economics, and social sciences into the standard curriculum, and he published several works on these topics, including Essay on a Course of Liberal Education for Civil and Active Life (1765), in which he challenged the benefits of traditional classical education by arguing that education should anticipate the practical needs of students. In his Lectures on History and General Policy (1788), Priestley presented a millennial conception of history which, he argued, furthered an understanding of God's natural laws. A number of colleges incorporated the Lectures, including Cambridge, Brown, Princeton, and Yale. In 1764 the University of Edinburgh granted him an honorary Doctor of Law in recognition of his contributions to the teaching of history. Priestley also became interested in the study of electricity, and, encouraged by his friend Benjamin Franklin, conducted a number of experiments and drafted a history of electricity which was published in 1767. In 1766 he was elected for a fellowship in the Royal Society (Benjamin Franklin was one of his recommenders).

Priestley left Warrington in 1767 to accept an appointment as a minister in Leeds, perhaps because of his wife's ill health or because he sought a more stable income. During his time at Leeds, he published several major theological works, including the Institutes of Natural and Revealed Religion (1772-4), in which he laid out some of the doctrines that subsequently became the standards of Unitarianism. Priestley also published several controversial pamphlets on religious topics that found a wide readership.

By the early 1770s, Priestley had attracted the attention of William Petty, 1st Earl of Shelburne (1737-1805). The grandson of the great scientist of the same name, Shelburne was a prominent politician, a future Prime Minister, and a magnanimous patron. Through him, Priestley not only achieved financial security, but gained entrée into the highest of Britain's intellectual, social, and scientific circles, including the Bowood Group, which included Isaac Barré (1726-1802), the jurist John Dunning (1731-1783), the bishop Jonathan Shipley (1714-1788), and Richard Price (1723-1791, APS 1785). At Shelburne's estate, Priestley pursued the implications of a paper he had presented to the Royal Society in 1772, "On Different Kinds of Air," and thus laid the foundation of his international reputation as a chemist. That year he also published a pamphlet Directions for Impregnating Water with Fixed Air, which explained the method for making soda water. In 1773 the Royal Society awarded him the Copley Medal for his accomplishments. The same year Priestley accepted the position in the Earl's household as tutor, librarian, and companion, tasks that left him plenty of time to pursue his intellectual interests and that took him on a tour of Europe as the Earl's companion.

In 1774 Priestley published Experiments and Observations on Different Kinds of Air , in which he built upon the work of Joseph Black and James Cavendish to identify nine distinct gases, three of which were previously unknown. Most famously, on August 1, 1774, he produced "dephlogisticated air" – oxygen – by heating red mercuric oxide, demonstrating beyond cavil that air was not an element. In isolating oxygen, Priestley noted its importance in combustion, but clung to a belief in phlogistic theory for the remainder of his life, becoming, at the end, the last important chemist of that stripe. His scientific work earned Priestley admission into the French Academy of Sciences in 1772, the St. Petersburg Academy in 1780, and through Franklin, to the American Philosophical Society in 1784.

During the later 1770s, divisions between Priestley and Shelburne deteriorated over Priestley's support for the American Revolution and over his unorthodox religious views. While the two remained cordial, Priestley left the Shelburne home in 1780 and settled at Birmingham, near his brother-in-law, John Wilkinson. Whereas his scientific work had flourished at Bowood, his religious writings flourished in Birmingham, and he became a leading dissenting voice, assailing the corruptions of the Anglican hierarchy and Trinitarianism, and beginning the enduring association with Unitarianism that he considered his true life's work. At Birmingham he was also drawn into the Lunar Society, an engaging, salon-like group of enlightened minds that included Erasmus Darwin (1731-1802, APS 1792), James Watt (1736-1819), Matthew Boulton (1728-1809), and Josiah Wedgwood (1730-1795).

The halcyon days in Birmingham, however, were not to last. Priestley's religious and political views conspired to ensure his supreme unpopularity during the shifting political tides of the French Revolutionary era, and he became a lightning rod for the government-inspired backlash against republicanism and "radicalism" of all sorts. The wrath of the mob was turned against him directly during the Birmingham riots of July, 1791, when his house, library, and laboratory were set aflame. Priestley took refuge with William Vaughan, brother of John (1756-1841, APS 1784) and Benjamin (1751-1835, APS 1786), all of whom Priestley had taught at Warrington Academy, and with whom he had remained on friendly terms. The Vaughn brothers would repeatedly offer their assistance over the next few years. When it became clear that the British government would not protect him from further attacks, Priestley whisked his children out of the country and in April, 1794, finally abandoned England for the United States.

After a brief visit to New York, where his arrival was widely celebrated, Priestley went to Philadelphia. Here, too, he wrote in a letter to John Wilkinson, he was welcomed "with the most flattering attention by all persons of note." The "persons of note" included several members of the American Philosophical Society, such as his old friend John Vaughan as well as Benjamin Rush (1745-1813, APS 1768) and David Rittenhouse (1732-1796, APS 1768), with whom he became particularly well acquainted. He turned down an invitation to teach chemistry at the University of Pennsylvania and instead settled with his family in the relatively remote town of Northumberland, Pennsylvania, 150 miles west of Philadelphia, initially imaging that he could enjoy the country life and yet travel into the metropolis for intellectual stimulation. Little, however, went as Priestley had intended. His plans of establishing a community at Northumberland devoted to religious and political freedom were unavailing, travel into Philadelphia proved far too difficult, and in his rural remove he was only barely able to continue his scientific research. In his letters to acquaintances he complained repeatedly that his endeavors were greatly hampered for lack of adequate communications with the outside world due to limited postal delivery and lack of access to the latest news from Europe. He devoted considerable energy to the establishment of the Northumberland Academy, but by the fall of 1795 it was clear that he had failed to attract Englishmen of substance to settle in Northumberland. Moreover, in 1795 and 1796, he lost his son and wife to disease, and thereafter he was never in complete health himself.

In 1796 Priestley temporarily returned to Philadelphia. There he delivered sermons at the Universalist Church and he attended the meetings of the American Philosophical Society. His last scientific work (on the long-abandonded phlogiston) was published in 1796. Priestley also spent much time with old and new friends, including Rittenhouse, John Adams, and, after 1796, Thomas Jefferson. His increasingly apparent sympathies for the Anti-Federalists made Priestley a favorite target for the literary quills of William Cobbett, also known as Peter Porcupine, especially after the capture of some letters addressed to Priestley revealed that he may be planning to settle in France. Cobbett's venomous attacks and damaging political allegations provoked Priestley to defend himself in print, after years of trying to remain aloof of the increasingly divisive "party spirit." Against the advice of his friends, including John and Benjamin Vaughan, he published his Letters to the Inhabitants of Northumberland, which provoked only more criticism from the friends of the Adams administration. When his friend Thomas Cooper (1759-1839) was arrested for violating the Alien and Sedition Acts, Priestley was suspected of aiding and abetting. His deportation was only prevented by President Adams, an old admirer who used to be quite friendly with Priestley until the mid-1790s. It was not until after the election of Jefferson that much of the abuse of Priestley was replaced by an increasingly favorable view of his political views. The "vast exertions of his genius," Jefferson remarked later, had fnally been recognized in his chosen home. John Adams wrote to John Vaughan in 1813 that Priestley was "Certainly one of the greatest Men in the World, and certainly one of the weakest." Even though the last decade of his life was marked to some extent by decline and disappointment, the significance of his contributions to eighteenth century religious, scientific, pedagogical and political thought was uncontested. He published over 150 works on topics ranging from education to theology, to natural and political philosophy. By the time of his death in Northumberland in 1804, Priestley had been elected to every major scientific society in Europe and North America. As one biographer noted, he aimed to "put the most 'advanced' Enlightenment ideas into the service of a rationalized though heterodox Christianity, under the guidance of the basic principles of scientific method."

Collection Information

Physical description

1 microfilm reel.


Restrictions on Use:

Those wishing to quote from or reproduce material on this film should first obtain permission from the Librarian, Dr. William's Library, London.


Purchased from Dr. William's Library, London, (£7.00) and accessioned, 1974 (1974 254mf).

Location of originals:

Originals in Dr. William's Library, London.

Early American History Note

This is a microfilm of an early American collection that may be of interest to researchers at the APS and may complement an original manuscript collection at the APS.

General note

Guide to this correspondence on microfilm reel.

Indexing Terms


  • Microfilm Collection

Personal Name(s)

  • Belsham, Thomas, 1750-1829
  • Lindsay, Theophilus, 1723-1808
  • Priestley, Joseph, 1733-1804


  • Natural history.
  • Science.
  • Theology -- History -- 18th century.