Its retail price was five Pennsylvania dollars per volume, about 15% less than the price of "Britannica" in America, subject to import tax on British books. Purchasers included George Washington, Thomas Jefferson, Aaron Burr and Alexander Hamilton. The original printing of 2,000 copies had sold out by 1818, at which time he still had a quantity of the 3-volume supplement remaining. To sell it, he had new title pages for the 3 volumes printed up dated 1818, and called them the Encyclopedia. By the time of Dobson's death in 1823 the Encyclopædia was outdated, and was eventually superseded by the first edition of "Encyclopedia Americana" (1829-1833). Dobson did not approve of door-to-door sales, which had been used by his contemporary Parson Weems to sell William Guthrie's "New System of Modern Geography" and Oliver Goldsmith's "History of the earth and Animated Nature". The door-to-door approach also seemed impractical, given the "Encyclopædia's" price and the long printing time of nine years. Instead, Dobson conducted an all-out advertising blitz, unlike any before seen in North America, to secure subscriptions; his advertisements appeared in newspapers, on magazine wrappers, in spare book leaves, and in pamphlets distributed to all the major book-sellers of his day. Dobson also appealed strongly to the patriotic pride of the newly independent Americans; he used only American materials and craftspeople and his announcement of the first "American" encyclopedia was timed to match George Washington's selection as the first President under the new Constitution. His first advertisements appeared on 31 March 1789 in three newspapers: the "Pennsylvania Mercury", the "Pennsylvania Packet", and the "Federal Gazette". Like the "Britannica", Dobson's "Encyclopædia" was published in weekly numbers, which could be then bound into volumes or half-volume parts. The price of each number was "one quarter of a dollar". The first weekly number was published on 2 January 1790, followed the next week by the second number. Dobson continued his regular printings until a fire destroyed his business and stock on an early Sunday morning, 8 September 1793; the heat of the fire was sufficient to melt much of his metal print parts. Dobson was again printing his "Encyclopædia" within a month. Dobson encountered some editorial difficulties, most notably on the essay concerning Quakers in Volume 15, which roused some indignation in Philadelphia, the home of many Quakers.