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Elisha Gray

August 9, 2021

When I was a child, my city's fire department had a contest in which it distributed a thin coloring books with a fire safety theme to children. Sparky the Fire Dog was a featured image.[1] Completed coloring books dropped into a box at the local fire station were judged in a contest in which it's likely that every entrant was declared a winner. As a prize, I got a tour of the main fire station that contained the signal center for the city's fire alarm network.

Fire alarm boxes once adorned a utility pole near every city block. Pulling a lever would signal that there was a fire in that area. Once in that area, the firefighters would be directed to the exact location of the fire. This was an important device in its hundred years of use before ubiquitous telephony. Without such a device, a person on horseback would need to race to the fire station.

Although I was just an elementary school student, I was intrigued by the method used to distinguish one alarm box from another without needing wires linking every box to the signal center. A motorized cam would switch a circuit in a coded pattern that identified the alarm box. The motor was likely spring powered, and the lever pull would extract a pin from a shaft to allow its rotation. The boxes were all connected in a continuous current loop.

Elisha Gray (1835-1901)

Elisha Gray (1835-1901).

Gray spent his early life on a farm, but he attended Oberlin College to study electrical devices. Gray didn't graduate from Oberlin, but he taught science and electricity there, and built laboratory equipment for its science departments.

Gray was awarded his first of more than seventy patents, for a self-adjusting telegraph relay, in 1865.

(Image from page 795 of "Ancestors and descendants of Andrew Moore, 1612-1897," by John Andrew Moore Passmore, 1897, via Wikimedia Commons.)

One of the first such alarm systems was invented in 1871 by electrical engineer and prolific inventor, Elisha Gray (1835-1901), best known for his telephone competition with Alexander Graham Bell (1847-1922).[2-6] If Gray's inventions had priority over Bell's, we wouldn't have had a Ma Bell. Instead, we would have had a different Gray Lady than The New York Times, the once revered newspaper that's now disdained for its penchant for clickbait headlines.

The first municipal electric fire alarm system, invented by William Francis Channing (1820-1901) and Moses Farmer, was installed in Boston on April 28, 1852, and its first alarm was received just a day later. on April 29, 1852, at 8:25 PM.[6] At the turn of the 21st century, Boston still had approximately 1500 fire alarm boxes in service on its streets, and a thousand boxes in public and private buildings.[6] The Boston Electric Fire Alarm System was dedicated as an IEEE Milestone on October 1, 2004.[6]

Most of Gray's life was devoted to communication, telegraphy being his principal interest at the start. He was co-founder with Enos M. Barton (1842-1916) of the Gray & Barton Company in 1869 as a supplier of telegraph equipment to the Western Union Telegraph Company. One of his first telegraph inventions was a multi-tone telegraph, invented in 1876, which required a separate circuit for each tone.[7] The complication of needing multiple circuits is the likely reason that this invention was never used. This device was a variation of his 1875 patent, "Electric Telegraph for Transmitting Musical Tones," that used steel reeds electromagnetically pulsed into vibration.[8] This 1875 invention is considered by many to be the first music synthesizer.

Fig. 1 from US Patent No. 173,618, 'Improvement in electro-harmonic telegraphs,' by Elisha Gray, February 15, 1876.

Fig. 1 from US Patent No. 173,618, "Improvement in electro-harmonic telegraphs," by Elisha Gray, February 15, 1876.[7]

The tone aspect of this patent, which was issued subsequent to his 1875 patent, US Patent No. 166.095, "Electric Telegraph for Transmitting Musical Tones,"[8] can be seen from the representation of a musical keyboard.

(Via Google Patents.[7] Click for larger image.)

Another of Gray's inventions was his 1887 telautograph, a device designed to transmit handwriting on telegraph systems.[9] Gray invented many improvements to this system, and the devices were sold by the Gray National Telautograph Company, created in 1888 to eventually become part of Xerox in the 1990s. Gray also conceived a closed-circuit television that he called the telephote, and he developed an underwater signaling device for sending messages to ships. This was his last invention, since Gray succumbed to a heart attack on January 21, 1901.

Behind every important technology are teams of lawyers that argue that their client is its inventor. Such was true in the battle between Gray and Alexander Graham Bell in the invention of the telephone transmitter (the device you speak into that converts your voice to an electrical signal. Both Gray and Bell invented a liquid transmitter, a simple device that converts sound to a variable resistance through use of a diaphragm dipping a needle into a conductive liquid (see figure). There's a principle in patent law called due diligence in which an inventor needs to speedily develop his idea if he wants to claim priority. It's been noted that there was a determination by the United States Patent and Trademark Office that
"... While Gray was undoubtedly the first to conceive of and disclose the [variable resistance] invention, as in his caveat of 14 February 1876, his failure to take any action amounting to completion until others had demonstrated the utility of the invention deprives him of the right to have it considered."[11]

Fig. 1 of US Patent No.161.739, 'Improvement in transmitters and receivers for electric telegraphs,' by Alexander Graham Bell, April 6, 1875.

Fig. 1 of US Patent No.161.739, "Improvement in transmitters and receivers for electric telegraphs," by Alexander Graham Bell, April 6, 1875. As the patent describes the figure, "Adjoining the receiver I place a light lever... This lever is mounted to oscillate freely on a pivot or axis, and one of its ends, f overhangs the free end of the vibratory armature... the lever is attached a platinum bow, j, the two ends of which extend down toward two mercury cups... when, by the action of the vibrating receiver the lever is tilted, the platinum points are depressed far enough to dip well into the mercury, thus completing the local circuit and exciting the electromagnetic instrument in the circuit, which in this case is an ordinary Morse sounder." (Via Google Patents.)


  1. Sparky Website of the National Fire Protection Association.
  2. Karen C. S. Donnelly, "Domestic Security: The Holmes Burglar AlarmTelegraph, 1853-1876," University of Pennsylvania Masters Thesis, 1992.
  3. Elisha Gray, "Improvement in electro-magnetic annunciators," US Patent No. 118,231, August 22, 1871 (via Google Patents).
  4. Elisha Gray, "Improvement in electro-magnetic annunciators," Reissue 6,825 of U.S. Patent No. 118,231, December 28, 1875 (via Google Patents).
  5. Elisha Gray, "Improvement in electro-magnetic annunciators," US Patent No. 162,057, April 13, 1875 (via Google Patents).
  6. Milestones:Electric Fire Alarm System, 1852, IEEE Boston Section, October 1, 2004, Engineering and Technology History Wiki.
  7. Elisha Gray, "Improvement in electro-harmonic telegraphs," US Patent No. 173,618, February 15, 1876 (via Google Patents).
  8. Elisha Gray, "Electric Telegraph for Transmitting Musical Tones," US Patent No. 166,095, July 27, 1875 (via Google Patents).
  9. Elisha Gray, "Telautograph," US Patent No. 386,815, July 21, 1888 (via Google Patents).
  10. Alexander Graham Bell."Improvement in transmitters and receivers for electric telegraphs," US Patent No.161.739 (April 6, 1875).
  11. Burton H. Baker, "The Gray Matter: The Forgotten Story of the Telephone," Telepress (January 31, 2000), ISBN‎ 978-0615113296 (via Amazon).

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