Elisha Gray and the Race to Patent the Telephone

Elisha Gray also invented a version of the telephone

Elisha Gray portrait

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Elisha Gray was an American inventor who contested the invention of the telephone with Alexander Graham Bell. Elisha Gray invented a version of the telephone in his laboratory in Highland Park, Illinois.

Background - Elisha Gray 1835-1901

Elisha Gray was a Quaker from rural Ohio who grew up on a farm. He studied electricity at Oberlin College. In 1867, Gray received his first patent for an improved telegraph relay. During his lifetime, Elisha Gray was granted over seventy patents for his inventions, including many important innovations in electricity. In 1872, Gray founded the Western Electric Manufacturing Company, the great-grandparent of today's Lucent Technologies.

Patent Wars - Elisha Gray Vs Alexander Graham Bell

On February 14, 1876, Alexander Graham Bell's telephone patent application entitled "Improvement in Telegraphy" was filed at the USPTO by Bell's attorney Marcellus Bailey. Elisha Gray's attorney filed a caveat for a telephone just a few hours later entitled "Transmitting Vocal Sounds Telegraphically."

Alexander Graham Bell was the fifth entry of that day, while Elisha Gray was 39th. Therefore, the U.S. Patent Office awarded Bell with the first patent for a telephone, US Patent 174,465 rather than honor Gray's caveat. On September 12, 1878 lengthy patent litigation involving the Bell Telephone Company against Western Union Telegraph Company and Elisha Gray began.

What Is a Patent Caveat?

A patent caveat was a type of preliminary application for a patent that gave an inventor an additional 90 days grace to file a regular patent application. The caveat would prevent anyone else that filed an application on the same or similar invention from having their application processed for 90 days while the caveat holder was given an opportunity to file a full patent application first. Caveats are no longer issued.

Elisha Gray's Patent Caveat Filed on February 14, 1876

To all whom it may concern: Be it known that I, Elisha Gray, of Chicago, in the County of Cook, and State of Illinois, have invented a new art of transmitting vocal sounds telegraphically, of which the following is a specification.

It is the object of my invention to transmit the tones of the human voice through a telegraphic circuit and reproduce them at the receiving end of the line so that actual conversations can be carried on by persons at long distances apart.

I have invented and patented methods of transmitting musical impressions or sounds telegraphically, and my present invention is based on a modification of the principle of said invention, which is set forth and described in letters patent of the United States, granted to me July 27th, 1875, respectively numbered 166,095, and 166,096, and also in an application for letters patent of the United States, filed by me, February 23d, 1875.

To attain the objects of my invention, I devised an instrument capable of vibrating responsively to all tones of the human voice, and by which they are rendered audible.

In the accompanying drawings I have shown an apparatus embodying my improvements in the best way now known to me, but I contemplate various other applications, and also changes in the details of construction of the apparatus, some of which would obviously suggest themselves to a skillful electrician, or a person in the science of acoustics, in seeing this application.

Figure 1 represents a vertical central section through the transmitting instrument; Figure 2, a similar section through the receiver; and Figure 3, a diagram representing the whole apparatus. 

My present belief is, that the most effective method of providing an apparatus capable of responding to the various tones of the human voice, is a tympanum, drum or diaphragm, stretched across one end of the chamber, carrying an apparatus for producing fluctuations in the potential of the electric current, and consequently varying in its power.

In the drawings, the person transmitting sounds is shown as talking into a box, or chamber, A, across the outer end of which is stretched a diaphragm, a, of some thin substance, such as parchment or gold-beaters' skin, capable of responding to all the vibrations of the human voice, whether simple or complex. Attached to this diaphragm is a light metal rod, A', or other suitable conductor of electricity, which extends into a vessel B, made of glass or other insulating material, having its lower end closed by a plug, which may be of metal, or through which passes a conductor b, forming part of the circuit.

This vessel is filled with some liquid possessing high resistance, such, for instance, as water, so that the vibrations of the plunger or rod A', which does not quite touch the conductor b, will cause variations in resistance, and, consequently, in the potential of the current passing through the rod A'.

Owing to this construction, the resistance varies constantly in response to the vibrations of the diaphragm, which, although irregular, not only in their amplitude, but in rapidity, are nevertheless transmitted, and can, consequently, be transmitted through a single rod, which could not be done with a positive make and break of the circuit employed, or where contact points are used.

I contemplate, however, the use of a series of diaphragm in a common vocalizing chamber, each diaphragm carrying and independent rod, and responding to a vibration of different rapidity and intensity, in which case contact points mounted on other diaphragms may be employed.

The vibrations thus imparted are transmitted through an electric circuit to the receiving station, in which circuit is included an electromagnet of ordinary construction, acting upon a diaphragm to which is attached a piece of soft iron, and which diaphragm is stretched across a receiving vocalizing chamber c, somewhat similar to the corresponding vocalizing chamber A.

The diaphragm at the receiving end of the line is this thrown into vibration corresponding with those at the transmitting end, and audible sounds or words are produced.

The obvious practical application of my improvement will be to enable persons at a distance to converse with each other through a telegraphic circuit, just as they do now in each other's presence, or through a speaking tube.

I claim as my invention the art of transmitting vocal sounds or conversations telegraphically through an electric circuit.

Elisha Gray

William J. Peyton
Wm D. Baldwin

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Your Citation
Bellis, Mary. "Elisha Gray and the Race to Patent the Telephone." ThoughtCo, Feb. 16, 2021, thoughtco.com/elisha-gray-race-to-patent-telephone-1991863. Bellis, Mary. (2021, February 16). Elisha Gray and the Race to Patent the Telephone. Retrieved from https://www.thoughtco.com/elisha-gray-race-to-patent-telephone-1991863 Bellis, Mary. "Elisha Gray and the Race to Patent the Telephone." ThoughtCo. https://www.thoughtco.com/elisha-gray-race-to-patent-telephone-1991863 (accessed June 6, 2023).