commercial port. Delays posed a major problem for shipping en route to
New York City , and bad weather could close the channel for days. Ships were forced to wait at the harbor's entrance for conditions to clear. These delays cost shipping companies substantial amounts of money, with each ship costing between $500 and $4000 per hour it was stopped (roughly $5,700 to $46,000 in 2013 dollars).
[2]
A ship received by a pair of induction coils hung on opposite sides of the ship, and fed through an amplifier into a headset (see diagram, below). By switching between coils, the relative strength of the signal on each side could be compared. The ship maintained a course parallel to the cable by maneuvering to keep the signal strength constant.[7]
Research and development
Two-stage vacuum-tube amplifier alternately takes input from inductance coils (top) hung on each side of ship.[8]
The pilot cable required a series of prior discoveries and inventions. In 1882, A. R. Sennett patented the use of a submerged electrical cable to communicate with a ship at a fixed location. Around the same time Charles Stevenson patented a means of navigating ships over an electrically charge cable using a galvanometer . The method became practical when Earl Hanson adapted early vacuum tube circuits to amplify the signal.[9]
launch for the first round of tests before moving to a steel-hulled
submarine for later tests.
[13] Both types of vessel picked up the signal and followed the underwater test cable without problem.
[14]
Installation and testing
Commander R. F. McConnell on the USS Semmes with the "Hanson apparatus".[15]
Following the successful tests at New London, the Navy proceeded to large scale testing in Ambrose Channel late in 1919. The minelayer Ord laid a pilot cable composed of 2,000 feet of leaded and armored cable, 2,000 feet of leaded cable, and 83,000 feet of standard rubber-insulated cable.[16] The USS O'Brien was fitted with receiving equipment and attempted to follow the cable out of the channel. Unfortunately, it was unable to detect a signal past the 1,000 foot mark, where a break in the cable had prevented the signal from continuing.[17] The break in the cable was repaired, but over the course of the winter of 1919–1920, crews found that the cable had broken in a total of fifty-two different places due to the strain placed on it while it was being laid. The damage was irreparable.[18] Going back to the drawing board, engineers tested 150-foot segments of three different types of cable and used the results to design a new full-size pilot cable.[19] The Navy ordered 87,000 feet of cable from the Simplex Wire and Cable Company in Boston.[20]
Once complete, the cable was loaded onto the USS Pequot in the Boston Navy Yard . The ship arrived in New York on July 31, 1920.[21] Ambrose Channel was already crossed by three telegraph cables, owned by Western Union , the Army , and the police , all of which had to be raised to the surface so the pilot cable could be laid underneath them.[22] The installation of the cable was completed on August 6, 1920,[23] and by August 28, electrical tests showed that both the sending and receiving circuits were functioning properly.[24] The Navy tested the cable using the seagoing tug USS Algorma . It then invited "representatives of various radio companies, shipping interests, pilots' associations, governmental bureaus, naval attaches, and others" for a public demonstration on board the destroyer USS Semmes from October 6 through October 9.[25] The ship's windows were covered with canvas and the captains took turns navigating using only the audio cues from the cable.[26]
The cable was well received. Even before the New London tests, the Washington Post called it "the greatest development in marine travel since the invention of the steam turbine"[27] and the Los Angeles Times declared the technology to be "one of the greatest peacetime gifts that science has devised."[28] Once operational, the latter newspaper called it "the greatest safeguard devised for shipping in modern history".[29] According to a 1921 trade magazine, leader cables had five functions: "to enable a ship to make a good landfall in thick weather, to lead a ship up the harbor, to lead a ship from open water through a restricted channel to open water on the far side, to give warning of outlying dangers, and to assist a vessel to keep a straight course from port to port and thus save fuel."[30]
In 1922, the publication Radio World stated that the cable's first two years of operation had been successful.[31] Also in 1922, Radio Broadcast boasted about the money saved by the cable as well as the ease of using it.[32] The cable itself was paid for using public funds, but it was the responsibility of ship owners to outfit their vessels with receiving equipment. Installation of the cable cost roughly $50,000[33] and the listening apparatus installed on each ship using the channel cost $1,200,[34] compared with hourly costs of delays that ranged from $500 to $4,000.[35] Radio Broadcast expressed the belief that navigation cables would become common for both ships and aircraft: "...there is a future for the audio cable... Its fullest usefulness at American ports and elsewhere waits, however, on that large appreciation of radio devices for sea as well as air navigation which pilots, both on the sea and in the air, expect, but do not as yet demand."[36]
Obsolescence and legacy
Despite the media hype, it appears that the Ambrose Channel pilot cable never met with large scale commercial success. Initially, some contemporaries of the cable proposed that it be extended several miles past the Ambrose light.[37] Such plans never came to fruition, as advances in technology rendered the pilot cable obsolete. By 1929 the Baltimore Sun reported ships navigating the Channel blindly without making any reference to the cable.[38] In that year, Marriott publicly complained that navigation cables still had unrealized potential for guiding ships. [39]
Leader cable systems appear to have been made obsolete by the refinement of
help ships navigate Ambrose Channel.
Earl Hanson, one of the key players in designing the Ambrose Channel cable, writing for Popular Mechanics, viewed it as a step toward applying radio cable technology in vast swaths of everyday life, including guiding aircraft and navigating and powering automobiles.autolanding.
[44] The cable found no more success in that role than it did in guiding ships. The
Blind Landing Experimental Unit later tried a similar system briefly before also abandoning it in favor of wireless.
[45]
References
Notes
^ Bond 1920 .
^ Wilhelm 1922 , p. 249.
^ Crossley 1921b , p. 280
^ Crossley 1921a , pp. 44–45.
^ Crossley 1921a , p. 51. Other voltages may have been used in subsequent operation.
^ New York Times 1920 , p. 6.
^ Crossley 1921a , pp. 46–47.
^ Crossley 1921a , p. 36.
^ Crossley 1921a , p. 34; Current History 1921 , p. 161
^ Geselowitz 2009 ; Marriott 1924 ; Woods 1980 , p. 523.
^ Wilhelm 1922 , p. 250
^ Wilhelm 1922 , p. 250.
^ Wilhelm 1922 , p. 250.
^ Wilhelm 1922 , p. 250.
^ Nautical Gazette 1920
^ Crossley 1921a , pp. 38–39.
^ Crossley 1921a , p. 40.
^ Crossley 1921a , p. 40; Wilhelm 1922 , p. 250.
^ Crossley 1921a , pp. 40–41.
^ Crossley 1921a , p. 42.
^ Crossley 1921a , p. 43.
^ Crossley 1921a , p. 43.
^ Crossley 1921a , pp. 38–39; New York Times 1920 , p. 6.
^ Los Angeles Times 1920 .
^ Crossley 1921a , p. 290.
^ New York Times 1920 , p. 6.
^ Washington Post 1919 , p. 21.
^ Los Angeles Times 1919 .
^ Los Angeles Times 1920 .
^ Bennett 1921 , p. 951.
^ Gordon 1922 , p. 72.
^ Wilhelm 1922 , p. 249.
^ Wilhelm 1922 , p. 249.
^ New York Times 1920 , p. 6.
^ Wilhelm 1922 , p. 249.
^ Wilhelm 1922 , p. 251.
^ Wilhelm 1922 .
^ Baltimore Sun 1929 ; Putnam 1924 , p. 215; Science 1924 , p. xiv.
^ Science News-Letter 1929 .
^ Putnam 1924 ; Radio Broadcast 1922 .
^ Putnam 1924 , p. 213.
^ Cooper 1930 , pp. 995–996
^ Hanson 1934 ; Yates & Pacent 1922 , p. 296.
^ Howeth 1963 , Chap. 28, §16 .
^ Wood 1930 , p. 13; Davis 1922 , p. 5; Armstrong 1930 , pp. 1–2; Perry 2004 , p. 100; Hanson 1919 , p. 489; Current History 1921 , p. 162.
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Armstrong, Robert (February 3, 1930), "Fog Menace Overcome", Los Angeles Times .
"Radio Beacon Guides Craft Through Fog", Baltimore Sun , p. MR9, August 18, 1929 .
Bennett, J.J. (1921), "The "Leader" Cable at Portsmouth" , Electrical World , McGraw-Hill, p. 951 .
Bond, A. Russell (December 1920), "The Radio Pilot-Cable" , St. Nicholas: an Illustrated Magazine for Boys and Girls , vol. 48, no. 2, p. 173 .
Conway, Erik (2008), "Chap. 2: Places to Land Blind" , Blind Landings: Low-Visibility Operations in American Aviation, 1918–1958 , JHU Press, .
Cooper, F. G. (August 8, 1930), "Aids to Navigation, Lecture III", Journal of the Royal Society of Arts , vol. 78, no. 4055, pp. 978–988 .
Crossley, A. (February 1921a), "Piloting Vessels by Electrically Energized Cables" , Journal of the American Society of Naval Engineers , 33 (1): 33–59, . Essentially same article as below.
Crossley, A. (August 1921b), "Piloting Vessels by Electrically Energized Cables" , Proceedings of the Institute of Radio Engineers , 9 (4): 273–294 . Essentially same article as above.
Current History , New York Times Company, 1921, pp. 161–163, retrieved 29 August 2013 .
Davis, Edward (Jul 10, 1922), "Fifteen Minutes of Radio Each Day", The Atlanta Constitution .
Gaulois, George (August 28, 1920), "New York's Radio Pilot Cable" , Scientific American , pp. 195, 210 .
Geselowitz, Michael N. (May 2009). "Robert H. Marriott" . IEEE Today's Engineer Online . IEEE. Retrieved 15 June 2013 .
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Marriott, Robert H. (May 1924), "As It Was in the Beginning" , Radio Broadcast : 51–59, retrieved 5 March 2018 .
"The Leader Cable System" , Nature , 106 (2676): 760–762, 10 February 1921, .
"Steamer travels into New York on a submerged radio "rail" " , The Nautical Gazette , vol. 99, no. 16, pp. 14–15, October 16, 1920 .
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"Warship Guided into Port by Radio Piloting Cable" (PDF) , The New York Times , pp. 1, 6, October 7, 1920 .
Putnam, George (June 15, 1924), "Radio Fog Signals for the Protection of Navigation; Recent Progress", Proceedings of the National Academy of Sciences of the United States of America , vol. 10, no. 6, pp. 211–218, .
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"5,000,000 Volt Artificial Lightning", The Science News-Letter , 15 (408): 61–62, February 2, 1929, .
Perry, Graham (2004), Flying People: Bringing You Safe Flying, Every Day , kea publishing, .
"Fog Tamed in Plan to Hasten Shipping", Washington Post , Sep 7, 1919 .
Wilhelm, Donald (July 1922), "The Audio Piloting Cable in the Ambrose Channel" , Radio Broadcast , vol. 1, no. 3, Doubleday, Doran, Incorporated, pp. 249–251 .
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Woods, David L. (1980), Signaling and communicating at sea , Arno Press [reprint?] .
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