From John Canton
AL: American Philosophical Society
Mr. Canton presents his Compliments to Dr. Franklin and begs to be inform’d whether, or not, in Writing to Dr. Priestley, he has mention’d Mr. C’s wanting Æpinus’s Tentamen Theoria Electricitatis et Magnetismi8 for Mr. Cavendish;9 if not, Mr. C would beg the Favour of a Frank.
Addressed: To / Doctor Franklin
7. So dated by the reference to the book by Aepinus, which BF had sent Priestley in April, to assist in his preparation of his History of Electricity; see above, p. 246.
8. For this book, in which Aepinus tried to use BF’s electrical theories to explain the phenomenon of magnetism, see above, X, 204.
9. Canton apparently means Henry Cavendish, not his father Charles; see above, X, 41 n. Henry developed Aepinus’ theory at length in a paper, “An Attempt to explain some of the principal Phenomena of Electricity, by Means of an Elastic Fluid,” published in Phil. Trans., lxi (1771), 584–677.