son, Thomas Jr., was living with the Priestleys, was a frequent visitor. Since his arrival in America, Priestley had continued to defend his Christian Unitarian beliefs; now, falling increasingly under the influence of Thomas Cooper and Elizabeth Ryland-Priestley, he was unable to avoid becoming embroiled in political controversy. In 1798, when, in response to the Pinckney affair, a belligerent President Adams sought to enlarge the navy and mobilise the militia into what Priestley and Cooper saw as a 'standing army', Priestley published an anonymous newspaper article: Maxims of political arithmetic, which attacked Adams, defended free trade, and advocated a form of Jeffersonian isolationism. In the same year, a small package, addressed vaguely: "Dr Priestley in America," was seized by the Royal Navy on board a neutral Danish boat. It was found to contain three letters, one of which was signed by the radical printer John Hurford Stone. These intercepted letters were published in London, and copied in numerous papers in America. One of the letters was addressed to "MBP", with a note: "I inclose a note for our friend MBP—but, as ignorant of the name he bears at present among you, I must beg you to seal and address it." This gave the intercepted letters a tinge of intrigue. Fearful lest they be taken as evidence of him being a 'spy in the interest of France', Priestley sent a clumsy letter to numerous newspaper editors, in which he naively named "MBP" (Member of the British Parliament) as Mr. Benjamin Vaughan, who "like me, thought it necessary to leave England, and for some time is said to have assumed a feigned name." William Cobbett, in his Porcupine's Gazette, 20 August 1798, added that Priestley "has told us who Mr MBP is, and has confirmed me in the opinion of their both being spies in the interest of France." Joseph Priestley Jr. left on a visit to England at Christmas 1798, not returning until August 1800. In his absence, his wife Elizabeth Ryland-Priestley and Thomas Cooper became increasing close, collaborating in numerous political essays. Priestley allowed himself to fall too heavily under Elizabeth and Cooper's influences, even helping hawk a seditious handbill Cooper had printed, around Point township, and across the Susquehanna at Sunbury. In September 1799, William Cobbett printed extracts from this handbill, asserting that: "Dr Priestley has taken great pains to circulate this address, has travelled through the country for