----, n.d., but ca. 3 pp. L. Concerning terrestrial magnetism. Has published a memoir thereon in collaboration with Mr. (Alexander von) Humboldt. Sends a copy to Mr. Jefferson and another for the A.P.S. See Minutes, July 19, 1805, Pro. XXII, pt. 3, 377. Microfilmed - Film 199, 118.
