MS in James Searle's hand (Adams Papers); endorsed in an unidentified hand: “Cyphers. Dana & JS”; filmed with Ciphers and Cipher Keys, Adams Papers, Microfilms, Reel No. 602.

This date derives from Dana's letter of 1 Jan. and JA's endorsement on that letter (descriptive note, and note 4, above). The letter of 1 Jan. was the first in which Dana used the code. He stated that James Searle, who was then at Amsterdam, would supply JA with a key. JA indicated in his endorsement that he replied to Dana's letter on 14 Jan. (not found), making it likely that he received it either on 14 Jan. or on the previous evening when he returned from a tour of the principal cities of the province of Holland (to the president of Congress, 14 Jan.; to C. W. F. Dumas, 14 Jan., both above). Since the manuscript is in Searle's hand, and he arrived in Brussels on 15 Jan., on his way back to Paris (from William Lee, 17 Jan., below), it seems likely that Searle wrote out the key for JA on or about 14 Jan. before he left Amsterdam.

Although attributed to Dana and Searle, the code probably originated with C. W. F. Dumas who used the code word for Congress as early as Oct. 1779 (Weber, Codes and Ciphers , p. 63–64).

Possibly William Alexander Jr., an intimate of Franklin who lived in the village of Auteuil, next to Passy. Alexander's daughter, Mariamne, was married to Jonathan Williams (vol. 8:170).