An earth battery is an early type of voltaic cell buried in the ground so that the soil acts as the electrolyte. The electrodes are made of two dissimilar metals such as iron and copper.

The earliest example of an earth battery is by Alexander Bain in 1841. Bain buried plates of zinc and copper in the ground about one meter apart and used the resulting voltage, of about one volt, to operate a clock. In 1898, Nathan Stubblefield received US patent 600457 for his electrolytic coil battery, which was a combination of an earth battery and a solenoid. The battery generated power for telegraph transmissions and the solenoid formed part of a tuned circuit that amplified the signalling voltage.

These devices were used by early experimenters as energy sources for telegraphy. However, in the process of installing long telegraph wires, engineers discovered that there were electrical potential differences between most pairs of telegraph stations, resulting from natural electrical currents (called telluric currents) flowing through the ground. Some early experimenters did not recognise that these currents were, in fact, partly responsible for extending the earth batteries' high outputs and long lifetimes.

External links

• "Alexander Bain (http://chem.ch.huji.ac.il/~eugeniik/history/bain.html)".
• Vassilatos, Gerry, "An Introduction to the Mysteries of Ground Radio (http://www.borderlands.com/newstuff/research/ground-myst.htm)".
• "Stubblefield Cell (http://www.icehouse.net/john1/stublefield1.html)".
• "Earth Batteries (http://www.icehouse.net/john1/earthbatt.html)". (icehouse.net)
• "Earth Batteries (http://geoffegel.tripod.com/earth.htm)". (geoffegel)

Patent

• Bryan, James C., "US160152 Earth Battery (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=160152.WKU.&OS=PN/160152&RS=PN/160152)". February 23, 1875.
• Dieckmann, George F., "US329724 Electric Earth Battery (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=329724.WKU.&OS=PN/329724&RS=PN/329724)". November 3, 1885.
• Stubblefield, Nathan, "US600457 Electric battery (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=600457.WKU.&OS=PN/600457&RS=PN/600457)". May 8, 1898.
• Ryeczek, "US4457988 Earth battery (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4457988.WKU.&OS=PN/4457988&RS=PN/4457988)". July 3, 1984.