the purpose, and is in fact the patron of it." He challenged Priestley to "clear himself of the accusation" or face prosecution." Barely a month later, in November and December 1799, Priestley stepped forward in his own defence, with his Letters to the inhabitants of Northumberland. Priestley's son, William, now living in Philadelphia, was increasingly embarrassed by his father's actions. He confronted his father, expressing John and Benjamin Vaughan’s unease, his own wife's concerns about Elizabeth Ryland-Priestley's dietary care, and his own concerns at the closeness of Elizabeth Ryland-Priestley and Thomas Cooper's relationship, and their adverse influence on Dr Priestley; but this only led to a further estrangement between William and his sister-in-law. When, a while later, Priestley's household suffered a bout of food poisoning, perhaps from milk sickness or a bacterial infection, Elizabeth Ryland-Priestley, falsely accused William of having poisoned the family's flour. Although this allegation has attracted the attention of some modern historians, it is believed to be without foundation. Priestley continued the educational projects that had always been important to him, helping to establish the "Northumberland Academy" and donating his library to the fledgling institution. He exchanged letters regarding the proper structure of a university with Thomas Jefferson, who used this advice when founding the University of Virginia. Jefferson and Priestley became close, and when the latter had completed his General History of the Christian Church, he dedicated it to President Jefferson, writing that "it is now only that I can say I see nothing to fear from the hand of power, the government under which I live being for the first time truly favourable to me." Priestley tried to continue his scientific investigations in America with the support of the American Philosophical Society, to which he had been previously elected a member in 1785. He was hampered by lack of news from Europe; unaware of the latest scientific developments, Priestley was no longer on the forefront of discovery. Although the majority of his publications focused on defending phlogiston theory, he also did some original work on spontaneous generation and dreams. Despite Priestley's reduced scientific output, his presence stimulated American interest in chemistry. By 1801, Priestley had become so ill that he could no longer write or experiment. He died on the morning of 6 February 1804, aged seventy and was buried at Riverview Cemetery in Northumberland, Pennsylvania. Priestley's epitaph reads: Legacy By the time he died