Note 5 — BATTERY TELEPHONES.
Reading edition
This property has long been known, but not applied. In 1856, in the second edition of my Exposé des applications d’Electricité, I pointed them out in speaking of the contact-breakers. I also spoke of them in a paper on electro-magnets (published in the Annales télégraphiques, 1865), and in several articles laid before the Académie des Sciences in 1872 and 1875 on the conductivity of filings and conducting powders. M. Clérac, in 1865, also used them to obtain variable resistances.