Autograph Letter Signed, addressed ‘Monsieur’, about Mr. Edison’s telephonic equipment, her husband’s commission to write an article about it, adding that her husband has already completed a work about electric light. In French, in need of further research. 2 pp. 8 x 5 inches, some light soiling. 26 March 1879. Camille Du Moncel, wife of Théodose Du Moncel (1821-1884), the prominent French physicist and advocate of the use of electricity. He invented many electrical devices and wrote several bookson the subject, including The Telephone, the Microphone and the Phonograph, 1879.