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Amos Emerson Dolbear (November 10, 1837 – February 23, 1910) was an American
physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...
and
inventor An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an ...
. Dolbear researched electrical spark conversion into sound waves and electrical impulses. He was a professor at
University of Kentucky The University of Kentucky (UK, UKY, or U of K) is a public land-grant research university in Lexington, Kentucky. Founded in 1865 by John Bryan Bowman as the Agricultural and Mechanical College of Kentucky, the university is one of the state ...
in
Lexington Lexington may refer to: Places England * Laxton, Nottinghamshire, formerly Lexington Canada * Lexington, a district in Waterloo, Ontario United States * Lexington, Kentucky, the largest city with this name * Lexington, Massachusetts, the oldes ...
from 1868 until 1874. In 1874 he became the chair of the physics department at
Tufts University Tufts University is a private research university on the border of Medford and Somerville, Massachusetts. It was founded in 1852 as Tufts College by Christian universalists who sought to provide a nonsectarian institution of higher learning. ...
in
Medford, Massachusetts Medford is a city northwest of downtown Boston on the Mystic River in Middlesex County, Massachusetts, United States. At the time of the 2020 U.S. Census, Medford's population was 59,659. It is home to Tufts University, which has its campus al ...
. He is known for his 1882 invention of a system for transmitting
telegraph Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas ...
signals without wires. In 1899 his patent for it was purchased in an unsuccessful attempt to interfere with
Guglielmo Marconi Guglielmo Giovanni Maria Marconi, 1st Marquis of Marconi (; 25 April 187420 July 1937) was an Italian inventor and electrical engineer, known for his creation of a practical radio wave-based wireless telegraph system. This led to Marconi ...
's
wireless telegraphy Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for ...
patents in the United States.


Biography

Amos Dolbear was born in
Norwich, Connecticut Norwich ( ) (also called "The Rose of New England") is a city in New London County, Connecticut, United States. The Yantic, Shetucket, and Quinebaug Rivers flow into the city and form its harbor, from which the Thames River flows south to ...
on November 10, 1837. He was a graduate of
Ohio Wesleyan University Ohio Wesleyan University (OWU) is a private liberal arts college in Delaware, Ohio. It was founded in 1842 by methodist leaders and Central Ohio residents as a nonsectarian institution, and is a member of the Ohio Five – a consorti ...
, in
Delaware, Ohio Delaware is a city in and the county seat of Delaware County, Ohio, United States. Delaware was founded in 1808 and was incorporated in 1816. It is located near the center of Ohio, is about north of Columbus, and is part of the Columbus, Ohio ...
. While a student there, he had made a "talking telegraph" and invented a receiver containing two features of the modern telephone: a permanent magnet and a metallic diaphragm that he made from a
tintype A tintype, also known as a melainotype or ferrotype, is a photograph made by creating a direct positive on a thin sheet of metal coated with a dark lacquer or enamel and used as the support for the photographic emulsion. Tintypes enjoyed their ...
. He invented the first telephone receiver with a permanent magnet in 1865, 11 years before
Alexander Graham Bell Alexander Graham Bell (, born Alexander Bell; March 3, 1847 – August 2, 1922) was a Scottish-born inventor, scientist and engineer who is credited with patenting the first practical telephone. He also co-founded the American Telephone and T ...
patented his model. Later, Dolbear couldn't prove his claim, so Bell kept the patent. Dolbear lost his case before the U. S. Supreme Court, (''Dolbear et al. v. American Bell Telephone Company''). The June 18, 1881 edition of ''
Scientific American ''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it ...
'' reported: In 1876, Dolbear patented a magneto electric telephone. He patented a static telephone in 1879. In 1882, Dolbear was able to communicate over a distance of a quarter of a mile without wires in the Earth. His device relied on conduction in the ground, which was different from later radio transmissions that used electromagnetic radiation. He received a U.S. patent for a wireless telegraph in March of that year. His set-up used phones grounded by metal rods poked into the earth. His transmission range was at least as much as a half a mile and he received a patent for this device, , in 1886. (He did not patent his system in Europe.) In 1899, The New England Wireless Telegraph and Telephone Company, a subsidiary of the American Wireless Telephone and Telegraph Company, purchased Dolbear's 1886 patent, and filed a suit against Marconi for infringement. However, in March 1901, a United States Circuit Court dismissed the suit. In April 1902, American Wireless petitioned Congress to extend the 1886 patent by ten years, but was unsuccessful, so it duly expired on October 4, 1903. In 1905, the New York Circuit Court further noted that the Dolbear patent was "inoperative, and that, even if operative, it operates by virtue of radically different electrical laws and phenomena" than the radio signaling used by Marconi."Marconi Wireless Telegraph Co. of America v. De Forest Wireless Telegraph Co. (Circuit Court, S. D. New York. April 11, 1905.)", ''The Federal Reporter. Volume 138. Cases Argued and Determined in the Circuit Courts of Appeals and Circuit and District Courts of the United States. July–September, 1905'', page 668. In 1868 Dolbear (while a professor at Bethany College) invented the electrostatic telephone. He also invented the opeidoscope (an instrument for visualizing vibration of sound waves, using a mirror mounted on a membrane) and a system of
incandescent light An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidat ...
ing. He authored several books, articles, and pamphlets, and was recognized for his contributions to science at both the Paris Exposition in 1881 and the Crystal Palace Exposition in 1882. In 1897, Dolbear published an article "The Cricket as a Thermometer" that noted the correlation between the ambient temperature and the rate at which
cricket Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by st ...
s chirp. The formula expressed in that article became known as
Dolbear's Law Dolbear's law states the relationship between the air temperature and the rate at which crickets chirp. It was formulated by Amos Dolbear and published in 1897 in an article called "The Cricket as a Thermometer". Dolbear's observations on the rela ...
. He died at his home in Medford on February 23, 1910.


Publications


Books

* ''The Art of Projecting'', Boston, 1876 * ''The Speaking Telephone'', 1877 * ''Sound and its Phenomena'', 1885 * ''Matter, Ether, and Motion'', Boston, 1892 * ''First Principles of Natural Philosophy'', Boston, 1897 * ''Modes of Motion'', Boston, 1897


Journal articles

*
The Cricket as a Thermometer
. ''The American Naturalist'', Vol. 31, No. 371 (November 1897), pp. 970–971. Published by The University of Chicago Press for The American Society of Naturalists


Patents

*
Apparatus for transmitting sound by electricity
' April 5, 1881.


References


External links

* *
Concise Encyclopedia of Tufts History - Dolbear, Amos Emerson, 1837–1910



Roxbury's Professor Dolbear

A portrait of Prof. Dolbear
{{DEFAULTSORT:Dolbear, Amos Emerson 1837 births 1910 deaths 19th-century American inventors 20th-century American inventors American physicists Ohio Wesleyan University alumni University of Kentucky faculty Tufts University faculty