coded messages published in newspapers and invisible ink, called a sympathetic stain, to write between the lines of what appeared to be typical letters. In the first months of the ring's operations, they were forced to rely on crude tactics to conceal their information before a complex web of codes and invisible ink were accessible, and so they relied on a small number of codes for memory. Woodhull used the codes 10 (New York), 30 and 40 (Post Riders), and 20 (Setauket) in his first letter of correspondence. Tallmadge realized the significance of creating a code book to increase their vocabulary. By July 1779, he had completed pocket dictionaries with lists of verbs, nouns, people, and places with their corresponding code numbers. The dictionaries were given to Washington, Woodhull, Townsend, and Tallmadge himself to ensure that they did not get into enemy hands. With the use of the codes, the letters were very complex and required much effort to write and comprehend. The code book helped Washington make sure that the Culper Ring spies had more support and operated in greater secrecy than previous Continental spies, perhaps with Nathan Hale in mind. Tallmadge, Woodhull, and Townsend were given code names and code numbers, along with Washington, Brewster, Roe, and Rivington. Washington's code number was 711. Other associates and informants The members of the ring gathered information from a variety of sources, including persons other than unwitting British officers. Some of those informants or associates included Joseph Lawrence, a Long Island resident; Captain Nathan Woodhull, Abraham Woodhull's uncle, who served as a Loyalist militia officer but provided information to Abraham; Nathaniel Ruggles, a schoolmaster and physician born in 1713; Joshua Davis, a Brewster deputy and occasional substitute; George Smith, a whaleboat man who filled in for Brewster near the end of the war; and William T. Robinson, a merchant. Alexander Rose writes that "John Cork" was a code name for an unidentified informant. Harry Thayer Mahoney writes that John Corke of Groton, New York posed as a Tory and could travel back and forth to New York City because he was "exceedingly intimate at British headquarters." Corke wrote intelligence reports to Tallmadge in invisible ink or reported verbally to him. Mahoney states that Washington and Tallmadge considered Corke a valuable recruit for the Culper Ring. A letter by Loyalist soldier Nehemiah Marks was uncovered in 2015 which identifies brothers Nathaniel and