Editing Telautograph (section)

==Invention==
[[File:PSM V14 D424 Elisha Gray.jpg|thumb|The inventor [[Elisha Gray]]]]
The telautograph's invention is attributed to the American engineer [[Elisha Gray]], who patented it on July&nbsp;31, 1888. Gray's patent stated that the telautograph would allow "one to transmit his own handwriting to a distant point over a two-wire circuit." It was the first facsimile machine in which the stylus was controlled by horizontal and vertical bars.<ref name="Huurdeman 2003">{{cite book|last=Huurdeman|first=Anton A.|url=https://books.google.com/books?id=SnjGRDVIUL4C&q=Telautograph+and+Elisha+Gray&pg=PA151|title=The Worldwide History of Telecommunications|date=2003|publisher=Wiley-Interscience|isbn=0-471-20505-2|location=Hoboken, New Jersey}}</ref> The telautograph was first publicly exhibited at the 1893 [[World's Columbian Exposition]] held in [[Chicago]].

[[File:Telautograph-1888 electronic writing device.png|thumb|upright|Telautograph patent schema]]

Gray started experimenting in 1887 with analog transmission of the pen position signals using [[rheostat|variable resistances]]<ref>{{cite patent
| country	= US
| number	= 494562
| inventor	= Elisha Gray
| status	= patent
| title		= Telautograph
| gdate		= 1893-04-04
| fdate		= 1887-07-16
| url		= https://patentimages.storage.googleapis.com/07/80/48/9c722755a75bb7/US494562.pdf
}}</ref> as was done in previous devices, but was dissatisfied with the performance he achieved.<ref name="MandB 1893 full">{{cite journal |title=The Telautograph |journal=The Manufacturer and Builder |date=April 1893 |volume=25 |issue=4 |pages=76–78 |url=https://babel.hathitrust.org/cgi/pt?id=coo.31924080796794&seq=82}}</ref> He then turned to pulse-based or digital pen position transmission. 

Gray's early patents<ref>{{cite patent
| country	= US
| number	= 386814
| inventor	= Elisha Gray
| status	= patent
| title		= Art of Telegraphy
| gdate		= 888-07-31
| fdate		= 1888-05-31
| url		= https://patentimages.storage.googleapis.com/b5/9e/7b/5014856747686c/US386814.pdf
}}</ref><ref>{{cite patent
| country	= US
| number	= 386815
| inventor	= Elisha Gray
| status	= patent
| title		= Telautograph
| gdate		= 1888-07-31
| fdate		= 1888-06-31
| url		= https://patentimages.storage.googleapis.com/da/8e/a4/84d3d83091d841/US386815.pdf
}}</ref> show devices to accomplish the required functions over two line wire circuits with a common ground connection. Pulses were sent over each wire to signal small steps of pen movement. Momentary current interruptions of a baseline [[direct current]] signaled pen lifting/lowering and paper feed, and changing polarities were used to encode pen movement direction. 

While the patent schema's geometry implies vertical and horizontal coordinates, Gray's first practical system (discussed later) had a different coordinate scheme, based on transmitting two radial distances along approximately diagonal directions from two fixed points. Later systems used in the 20th century<ref name="Ritchie 1900 US">{{cite patent
| country	= US
| number	= 656828
| inventor	= Foster Ritchie
| status	= patent
| title		= Telautographic Apparatus
| gdate		= 1900-08-28
| fdate		= 1900-01-29
| url		= https://patentimages.storage.googleapis.com/bd/7b/35/4733ac8e1e77eb/US656828.pdf
}}</ref>
transmitted the angle of two crank arm joints in a [[Five-bar_linkage|five bar linkage]], comprising two pen motor cranks, two pen linkage bars, and the body of the instrument.

In an 1888 interview in ''The Manufacturer & Builder'' (Vol. 24: No. 4: pages 85–86) Gray said:<ref>{{cite web|last=Tunney|first=Glenn |date=October 23, 2004|title=Elisha Gray Deserves Top Billing in Brownsville History|url=http://freepages.rootsweb.com/~glenntunneycolumn/history/column309.htm|access-date=April 30, 2022|website=Glenn Tunney's Column® and Brownsville Time Capsule®}}</ref>

<blockquote>By my invention you can sit down in your office in Chicago, take a pencil in your hand, write a message to me, and as your pencil moves, a pencil here in my laboratory moves simultaneously, and forms the same letters and words in the same way. What you write in Chicago is instantly reproduced here in fac-simile. You may write in any language, use a code or cipher, no matter, a fac-simile is produced here. If you want to draw a picture it is the same, the picture is reproduced here. The artist of your newspaper can, by this device, telegraph his pictures of a railway wreck or other occurrences just as a reporter telegraphs his description in words.</blockquote>

However these first devices were crude to the point of uselessness.<ref>{{cite web |title=Telautograph |url=https://ethw.org/Telautograph |website=Engineering and Technology History Wiki |date=3 October 2023 |access-date=20 October 2023}}</ref><ref>{{cite book |last1=Williams |first1=Archibald |title=The Romance of Modern Invention |date=1904 |publisher=J. B. Lippinscott Company; C. Arthur Pearson, Ltd |location=Philadelphia; London |page=80 |edition=3 |url=https://books.google.com/books?id=U0RIAAAAIAAJ |access-date=20 October 2023}}</ref> Some of his subsequent refinements<ref>{{cite patent
| country	= US
| number	= 461470
| inventor	= Elisha Gray
| status	= patent
| title		= Telautograph
| gdate		= 1889-06-13
| fdate		= 1891-10-20
| url		= https://patentimages.storage.googleapis.com/43/11/2a/8dd272acc5d345/US461470.pdf
}}</ref><ref name="US461470">{{cite patent
| country	= US
| number	= 461472
| inventor	= Elisha Gray
| status	= patent
| title		= Art Of and Apparatus For Telautographic Communication
| gdate		= 1891-10-20
| fdate		= 1889-09-17
| url		= https://patentimages.storage.googleapis.com/35/88/e9/d280c3780baad2/US461472.pdf
}}</ref>
changed the encoding scheme. They also mention use of four wires for increased speed and accuracy, but the additional wires were later abandoned.<ref>{{cite journal |journal=The Phonoscope |title= To Write Letters by Wire|date=July 1897 |volume=1 |issue=8 |page=11 |url=https://www.worldradiohistory.com/Archive-Phonoscope/1897/Phonoscope-1897-07.pdf}}</ref> It's clear from the commentary in these and other patents that Gray needed to increase the speed and accuracy of his pulse based system, and in fact he patented a large number of increasingly complicated and refined mechanisms to achieve this.<ref name="US491346">{{cite patent
| country	= US
| number	= 491346
| inventor	= Elisha Gray
| status	= patent
| title		= Electro-Mechanical Movement
| gdate		= 1893-02-07
| fdate		= 1892-01-08
| url		= https://patentimages.storage.googleapis.com/57/1f/af/f4372020e80895/US491346.pdf
}}</ref><ref name="US491347">{{cite patent
| country	= US
| number	= 491347
| inventor	= Elisha Gray
| status	= patent
| title		= Telautograph
| gdate		= 1893-02-07
| fdate		= 1892-09-21
| url		= https://patentimages.storage.googleapis.com/c9/71/8f/87c0e837567542/US491347.pdf
}}</ref><ref>{{cite patent
| country	= US
| number	= 522892
| inventor	= Elisha Gray
| status	= patent
| title		= Telautograph
| gdate		= 1894-07-10
| fdate		= 1893-03-08
| url		= https://patentimages.storage.googleapis.com/1b/1d/01/e4b3aa08949fb7/US522892.pdf
}}</ref>

[[File:Telautograph Receiver and Transmitter.png|thumb|right|Elisha Gray's Telautograph Receiver and Transmitter {{circa|1893}}]]

[[File:Firesideuniversi01mcgo2.jpg|thumb|right|Elisha Gray's Telautograph Transmitter and Receiver in use]]

In 1893 Gray's system<ref>{{cite web |title=Telautograph Copy Telegraph |url=https://artsandculture.google.com/asset/telautograph-copy-telegraph-encoder-right-and-receiver-left/wgHLNAr6gp9MgQ |access-date=20 October 2023}}</ref> using the mechanism seen in Pat. US491347<ref name="US491347" /> was good enough to exhibit at the Chicago World's Fair and at a Royal Society conversazione in London in 1894.<ref>{{cite web |last1=Standish Hartrick |first1=Archibald |title=Sending a message by the telautograph |url=https://artsandculture.google.com/asset/6QGqERHRYed7sA |publisher=Science Museum, London, United Kingdom}}</ref> An article in Manufacturer and Builder of this year describes the current and previous versions.<ref name="MandB 1893 full" /> Apparently at this stage Gray used 40 steps per inch. It's clear how challenging the technical problem was; a later film of a similar device<ref>{{cite web |title=Tele-Tales! |url=https://www.youtube.com/watch?v=VKrGCn167I4&t=166s |website=YouTube | date=13 April 2014 |publisher=British Pathé |access-date=20 October 2023}}</ref> shows the rapidity with which an operator might move the pen. This type of use would produce perhaps 600-1000 pulses per second on a digital system, a challenge for any electromechanical system connected over earth return telephone/telegraph lines. A more elegant technology was around the corner, and an analog coup was being staged at the turn of the century. 

[[File:Romance of Modern Invention Ritchie Telautograph.jpg|thumb|right|Foster Ritchie's Telautograph Receiver and Transmitter {{circa|1904}}]]

By the end of the 19th century the telautograph was modified<ref>{{cite patent |country=GB |number=189924048 |status=patent}}</ref><ref name="Ritchie 1900 US" /> by [[Foster Ritchie]], a former Gray assistant.<ref name="Coe 1993">{{cite book |last1=Coe |first1=Lewis |title=The Telegraph: A History of Morse's Invention and its Predecessors in the United States |date=1993 |publisher=McFarland and Company |isbn=0-89950-736-0 |page=21 |url=https://books.google.com/books?id=pzkZPIXm89UC |access-date=20 October 2023}}</ref> Calling it the telewriter, Ritchie's version of the telautograph could be used for either copying or speaking over the same telephone connection.<ref name="Ritchie 1906">{{cite patent |country=GB |number=190611957 |status=patent |url= https://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=190611957A&KC=A&FT=D&ND=3&date=19061018&DB=EPODOC&locale=en_EP}}</ref><ref name="Guardian 1908">{{cite journal |title=The Latest Business Convenience |journal=The Guardian |date=1908-12-16 |page=5 |url=https://www.newspapers.com/newspage/258592277/}}</ref><ref name="Williams 1904 p77">{{cite book |last1=Williams |first1=Archibald |title=The Romance of Modern Invention |date=1904 |publisher=J. B. Lippinscott Company; C. Arthur Pearson, Ltd |location=Philadelphia; London |page=77 |edition=3 |url=https://books.google.com/books?id=U0RIAAAAIAAJ&pg=PA77}}</ref>

Ritchie had returned to the analog principle<ref>{{cite book |last1=Williams |first1=Archibald |title=The Romance of Modern Invention |date=1904 |publisher=J. B. Lippinscott Company; C. Arthur Pearson, Ltd |location=Philadelphia; London |pages=72–82 |edition=3 |url=https://books.google.com/books?id=U0RIAAAAIAAJ&pg=PA72}}</ref> and made it work well. He did this by adding an [[Alternating_current|AC]] signal whenever the pen needed to be lowered, on top of the direct current position signal already on the line wires. The angle of the two pen [[Crank_(mechanism) | crank bars]] was turned into the position signal by two [[rheostat]]s, driving large [[Galvanometer|D'Arsonval]] movements at the receiver that moved similar crank bars, in turn moving the receiver pen. Interruption of the direct current advanced the paper. 

The AC pen lowering signal was highly important. If Ritchie understood the significance of this technique, he strangely failed to reveal (or protect) this principle in his patents. George S. Tiffany on behalf of the Gray National Telautograph Company understood the significance of the AC signal quite well. In the patent he filed shortly after and presumably in response to Ritchie<ref>{{cite patent
| country	= US
| number	= 668889
| inventor	= George S Tiffany
| status	= patent
| title		= Telautograph
| gdate		= 1901-02-26
| fdate		= 1900-10-19
| url		= https://patentimages.storage.googleapis.com/28/2e/b7/cad0c9f7a4265c/US668889.pdf
}}</ref>
he explains that the use of either an AC signal superimposed on the pen current signal or intentional mechanical vibrations added at the receiver can overcome static pen and actuator friction, and allow the pen to follow the transmitter quite perfectly. This principle is in common use today in the form of [[Dither#cite_note-1|dither]], as applied to proportional pneumatic and hydraulic control valves and regulators. A dither signal can overcome both magnetic hysteresis and static friction and was preferable to mechanical vibration, as later Telautograph designs<ref name="Tiffany 1906">{{cite patent
| country	= US
| number	= 954150
| inventor	= George S Tiffany
| status	= patent
| title		= Telautograph
| gdate		= 1910-04-05
| fdate		= 1906-02-05
| url		= https://patentimages.storage.googleapis.com/ea/57/59/c06d47eed3324c/US954150.pdf
}}</ref>
used it exclusively. 

Apparently this technique worked well, because even though Tiffany studiously avoided every constructional feature of Ritchie's patent, he used the exact same fundamental technique, and the analog telautograph principle continued to be used for at least the next 35 years,<ref name="Coe 1993" /> such as in those installed in the Frick Art Reference Library around 1935,<ref>{{cite web |last1=Duncan |first1=Sumitra |title=ONE HUNDRED YEARS AT THE LIBRARY: INNOVATION THROUGH TECHNOLOGY |url=https://www.frick.org/blogs/farl/one_hundred_years_technology |website=The Frick Collection |access-date=20 October 2023}}</ref> also see [https://ids.si.edu/ids/deliveryService?id=NMAH-MAH-30392 interior view]. Tiffany patents after 1901<ref name="Tiffany 1906" /><ref>{{cite patent
| country	= US
| number	= 1272874
| inventor	= George S Tiffany
| status	= patent
| title		= Telegraphic Apparatus
| gdate		= 1918-07-16
| fdate		= 1912-02-24
| url		= https://patentimages.storage.googleapis.com/73/42/61/c8bfcd1099ab91/US1272874.pdf
}}</ref> 
refined the mechanism but not the principle.

Ritchie marketed his design as the Telewriter in the UK. <ref>{{cite web |title=This 'Telewriter' Transmitted Handwriting Across Long Distances in the 1930s |url=https://gizmodo.com/this-telewriter-transmitted-handwriting-across-long-dis-1845641043 |website=Gizmodo |date=11 November 2020 |access-date=20 October 2023}}</ref><ref>{{cite web |title=Prof. Elisha Gray, and his Autotelegraph |url=http://www.hffax.de/history/html/gray.html |website=HF-Fax |access-date=20 October 2023}}</ref><ref name="Huurdeman 2003" /> The claim in this last reference that the phone and Ritchie's telautograph could be used simultaneously over the same line is dubious given the interference to be expected between the AC pen control signal and a phone signal, and statements to the contrary in Ritchie's patents.<ref name="Ritchie 1906" /> Contemporary accounts<ref name="Guardian 1908" /> describe the operations separately and not together or even describe the telautograph being disconnected when the telephone was in use.<ref name="Williams 1904 p77" />

All available images and descriptions of commercial telautographs after 1901 depict the open loop analog devices that Ritchie pioneered. While Tiffany did eventually design a [[servomechanism]] controlled telautograph in 1916<ref>{{cite patent
| country	= US
| number	= 1279178
| inventor	= George S Tiffany
| status	= patent
| title		= Telautographic System
| gdate		= 1918-09-17
| fdate		= 1916-05-02
| url		= https://patentimages.storage.googleapis.com/5a/3a/fb/acea0b2799178b/US1279178.pdf
}}</ref> it's not clear if this was ever commercialized.