Editing Teleprinter (section)

==History==
{{Organize section|date=March 2024|reason=it could be more easily read if subdivided by principle of operation}}
The teleprinter evolved through a series of inventions by a number of engineers, including [[Samuel Morse]], [[Alexander Bain (inventor)|Alexander Bain]], [[Royal Earl House]], [[David Edward Hughes]], [[Emile Baudot]], [[Donald Murray (inventor)|Donald Murray]], [[Charles L. Krum]], [[Edward Kleinschmidt]] and [[Frederick G. Creed]]. Teleprinters were invented in order to send and receive messages without the need for operators trained in the use of Morse code. A system of two teleprinters, with one operator trained to use a keyboard, replaced two trained Morse code operators. The teleprinter system improved message speed and delivery time, making it possible for messages to be flashed across a country with little manual intervention.<ref name="query.nytimes.com">{{Citation |title=Typewriter May Soon Be Transmitter of Telegrams |newspaper=[[The New York Times]] |date=January 25, 1914 |url=https://timesmachine.nytimes.com/timesmachine/1914/01/25/100081424.pdf}}</ref>

There were a number of parallel developments on both sides of the Atlantic Ocean. In 1835 [[Samuel Morse]] devised a recording telegraph, and [[Morse code]] was born.<ref>{{Cite web |url=http://collection.sciencemuseum.org.uk/objects/co32957/type-used-for-original-morse-telegraph-1835-movable-type |title=Type used for original morse telegraph, 1835 |website=[[Science Museum, London|Science Museum]] |access-date=2017-12-05 |quote=Samuel Morse was one of the pioneers of electric telegraphy. Prompted by receiving news of his wife's death too late to attend her funeral, Morse was determined to improve the speed of long distance communications (which at that point relied on horse messengers).}}</ref> Morse's instrument used a current to displace the armature of an electromagnet, which moved a marker, therefore recording the breaks in the current. Cooke & Wheatstone received a British patent covering telegraphy in 1837 and a second one in 1840 which described a type-printing telegraph with steel type fixed at the tips of petals of a rotating brass daisy-wheel, struck by an "electric hammer" to print Roman letters through carbon paper onto a moving paper tape.<ref>{{cite web |url=https://distantwriting.co.uk/cookewheatstone.html |title=3. Cooke and Wheatstone |last=Roberts |first=Steven |website=Distant Writing: A History of the Telegraph Companies in Britain between 1838 and 1868}}</ref> In 1841 [[Alexander Bain (inventor)|Alexander Bain]] devised an electromagnetic printing telegraph machine. It used pulses of electricity created by rotating a dial over contact points to release and stop a type-wheel turned by weight-driven clockwork; a second clockwork mechanism rotated a drum covered with a sheet of paper and moved it slowly upwards so that the type-wheel printed its signals in a spiral. The critical issue was to have the sending and receiving elements working synchronously. Bain attempted to achieve this using [[centrifugal governor]]s to closely regulate the speed of the clockwork. It was patented, along with other devices, on April 21, 1841.<ref>{{cite web |url=http://distantwriting.co.uk/bain.html |title=Distant Writing – Bain |author=Steven Roberts}}</ref>

By 1846, the [[Samuel Morse|Morse]] telegraph service was operational between Washington, D.C., and New York. [[Royal Earl House]] patented his [[printing telegraph]] that same year. He linked two 28-key piano-style keyboards by wire. Each piano key represented a letter of the alphabet and when pressed caused the corresponding letter to print at the receiving end. A "shift" key gave each main key two optional values. A 56-character typewheel at the sending end was synchronised to coincide with a similar wheel at the receiving end. If the key corresponding to a particular character was pressed at the home station, it actuated the typewheel at the distant station just as the same character moved into the printing position, in a way similar to the (much later) [[daisy wheel printer]]. It was thus an example of a synchronous data transmission system. House's equipment could transmit around 40 instantly readable words per minute, but was difficult to manufacture in bulk. The printer could copy and print out up to 2,000 words per hour. This invention was first put in operation and exhibited at the [[Mechanics Institute]] in New York in 1844.

Landline teleprinter operations began in 1849, when a circuit was put in service between Philadelphia and New York City.<ref>{{cite journal |journal=RTTY Journal |volume=25 |issue=9 |date=October 1977 |page=2 |url=https://archive.org/details/VO25NO8/page/n1/mode/2up |title=Silent Key – Edward Kleinschmidt}}</ref>

[[File:Printing Telegraph.jpg|thumb|[[David Edward Hughes|Hughes]] telegraph, an early (1855) teleprinter built by Siemens and Halske. The [[centrifugal governor]] to achieve synchronicity with the other end can be seen.|alt=]]
In 1855, [[David Edward Hughes]] introduced an improved machine built on the work of Royal Earl House. In less than two years, a number of small telegraph companies, including [[Western Union]] in early stages of development, united to form one large corporation – Western Union Telegraph Co. – to carry on the business of telegraphy on the Hughes system.<ref name="Clarkson">{{cite web |url=http://people.clarkson.edu/~ekatz/scientists/hughes.html |title=David Edward Hughes |access-date=September 29, 2010 |date=April 14, 2007 |publisher=Clarkson University |archive-url=https://web.archive.org/web/20080422072443/http://people.clarkson.edu/~ekatz/scientists/hughes.html |archive-date=April 22, 2008}}</ref>

In France, [[Émile Baudot]] designed in 1874 a system using a five-unit code, which began to be used extensively in that country from 1877. The British Post Office adopted the Baudot system for use on a simplex circuit between London and Paris in 1897, and subsequently made considerable use of duplex Baudot systems on their Inland Telegraph Services.<ref>{{cite web |last=Hobbs |first=Alan G. |title=Five-unit codes |url=http://www.nadcomm.com/fiveunit/fiveunits.htm |access-date=May 1, 2012}}</ref>

During 1901, Baudot's code was modified by [[Donald Murray (inventor)|Donald Murray]] (1865–1945, originally from New Zealand), prompted by his development of a typewriter-like keyboard. The Murray system employed an intermediate step, a keyboard perforator, which allowed an operator to punch a [[paper tape]], and a tape transmitter for sending the message from the punched tape. At the receiving end of the line, a printing mechanism would print on a paper tape, and/or a reperforator could be used to make a perforated copy of the message.<ref>{{cite magazine |last=Foster |first=Maximilian |date=August 1901 |title=A Successful Printing Telegraph |magazine=[[World's Work|The World's Work: A History of Our Time]] |volume=II |pages=1195–1199 |url=https://books.google.com/books?id=IF6tNZnhO7wC&pg=PA1195 |access-date=July 9, 2009}}</ref> As there was no longer a direct correlation between the operator's hand movement and the bits transmitted, there was no concern about arranging the code to minimize operator fatigue, and instead Murray designed the code to minimize wear on the machinery, assigning the code combinations with the fewest punched holes to the most [[letter frequencies|frequently used characters]]. The Murray code also introduced what became known as "format effectors" or "[[control character]]s" – the [[Carriage return|CR]] (Carriage Return) and [[Newline|LF]] (Line Feed) codes. A few of Baudot's codes moved to the positions where they have stayed ever since: the NULL or BLANK and the DEL code. NULL/BLANK was used as an idle code for when no messages were being sent.<ref name="query.nytimes.com"/>

In the United States in 1902, electrical engineer Frank Pearne approached [[Joy Morton]], head of [[Morton Salt]], seeking a sponsor for research into the practicalities of developing a [[printing telegraph]] system. Joy Morton needed to determine whether this was worthwhile and so consulted mechanical engineer [[Charles L. Krum]], who was vice president of the Western Cold Storage Company. Krum was interested in helping Pearne, so space was set up in a laboratory in the attic of Western Cold Storage. Frank Pearne lost interest in the project after a year and left to get involved in teaching. Krum was prepared to continue Pearne’s work, and in August, 1903 a patent was filed for a '[[typebar]] page printer'.<ref>{{cite patent |country=US |status=Patent |number=888335 |gdate=May 1908}}</ref> In 1904, Krum filed a patent for a 'type wheel printing telegraph machine'<ref>{{cite patent |country=US |status=Patent |number=862402}}</ref> which was issued in August, 1907. In 1906 Charles Krum's son, Howard Krum, joined his father in this work. It was Howard who developed and patented the start-stop synchronizing method for code telegraph systems, which made possible the practical teleprinter.<ref>{{cite patent |country=US |status=Patent |number=1286351 |fdate=May 1910 |gdate=December 1918}}</ref>

In 1908, a working teleprinter was produced by the Morkrum Company (formed between Joy Morton and Charles Krum), called the Morkrum Printing Telegraph, which was field tested with the Alton Railroad. In 1910, the Morkrum Company designed and installed the first commercial teletypewriter system on Postal Telegraph Company lines between Boston and New York City using the "Blue Code Version" of the Morkrum Printing Telegraph.<ref name="Colin Hempstead, William E. Worthington 2005 605">{{cite book |author=Colin Hempstead, William E. Worthington |url=https://books.google.com/books?id=0wkIlnNjDWcC&pg=PA605 |title=Encyclopedia of 20th Century Technology |year=2005 |page=605 |publisher=Routledge |isbn=9781579584641}}</ref><ref>{{cite web |url=http://www.baudot.net/teletype/MPT.htm |title=Morkum Printing Telegraph Page Printer |access-date=2011-08-15}}</ref>

In 1916, [[Edward Kleinschmidt]] filed a patent application for a typebar page printer.<ref>{{cite patent |inventor-last=KLEINSCHMIDT |inventor-first=E. |title=TELEGRAPH PRINTER |gdate=Apr 14, 1916 |country=US |number=1448750 |status=Patent}}</ref> In 1919, shortly after the [[Morkrum]] company obtained their patent for a start-stop synchronizing method for code telegraph systems, which made possible the practical teleprinter, Kleinschmidt filed an application titled "Method of and Apparatus for Operating Printing Telegraphs"<ref>{{cite patent |inventor-last=KLEINSCHMIDT |inventor-first=E. |title=METHOD OF AND APPARATUS FOR OPERATING PRINTING TELEGRAPHS |gdate=May 1, 1919 |number=1463136 |country=US |status=Patent}}</ref> which included an improved start-stop method.<ref name=historytelcom>{{cite book |last=Huurdeman |first=Anton A. |title=The Worldwide History of Telecommunications |publisher=Wiley-IEEE |year=2003 |pages=302 |isbn=0-471-20505-2}}</ref> The basic start-stop procedure, however, is much older than the Kleinschmidt and Morkrum inventions. It was already proposed by D'Arlincourt in 1870.<ref>{{cite book |last1=Deckert |first1=Jürgen |last2=Kösling |first2=Heinz |date=1987 |title=Fernschreibtechnik |trans-title=Teletype Technology |language=de |location=Berlin |publisher=Militärverlag der [[East Germany|Deutschen Demokratischen Republik]] ([[Volkseigener Betrieb|VEB]]) |isbn=3-327-00307-6}}</ref>

[[File:Siemens t37h without cover.jpg|thumb|Siemens t37h (1933) without cover]]
Instead of wasting time and money in patent disputes on the start-stop method, Kleinschmidt and the Morkrum Company decided to merge and form the [[Morkrum-Kleinschmidt]] Company in 1924. The new company combined the best features of both their machines into a new typewheel printer for which Kleinschmidt, Howard Krum, and Sterling Morton jointly obtained a patent.<ref name=historytelcom/>

In 1924 Britain's [[Creed & Company]], founded by [[Frederick G. Creed]], entered the teleprinter field with their Model 1P, a page printer, which was soon superseded by the improved Model 2P. In 1925 Creed acquired the patents for Donald Murray's Murray code, a rationalised Baudot code. The Model 3 tape printer, Creed’s first combined start-stop machine, was introduced in 1927 for the Post Office telegram service. This machine printed received messages directly on to gummed paper tape at a rate of 65 words per minute. Creed created his first keyboard perforator, which used compressed air to punch the holes. He also created a reperforator (receiving perforator) and a printer. The reperforator punched incoming Morse signals on to paper tape and the printer decoded this tape to produce alphanumeric characters on plain paper. This was the origin of the Creed High Speed Automatic Printing System, which could run at an unprecedented 200 words per minute. His system was adopted by the [[Daily Mail]] for daily transmission of the newspaper's contents. The Creed Model 7 page printing teleprinter was introduced in 1931 and was used for the inland [[Telex]] service. It worked at a speed of 50 baud, about 66 words a minute, using a code based on the Murray code.{{Citation needed|date=November 2017}}

A teleprinter system was installed in the [[Bureau of Lighthouses]], Airways Division, Flight Service Station Airway Radio Stations system in 1928, carrying administrative messages, flight information and weather reports.<ref>{{cite web |last=Schamel |first=John |title=Flight Service History 1920-1998 |website=Air Traffic Control History |date=2016-10-19 |url=http://www.atchistory.org/flight-service-history-1920-1998/}}</ref> By 1938, the teleprinter network, handling weather traffic, extended over 20,000 miles, covering all 48 states except Maine, New Hampshire, and South Dakota.<ref>{{Cite web |url=https://www.faa.gov/about/media/b-chron.pdf |title=FAA HISTORICAL CHRONOLOGY, 1926-1996 |website=faa.gov |date=2005-12-17 |archive-url=https://web.archive.org/web/20131105165930/http://www.faa.gov:80/about/media/b-chron.pdf |archive-date=2013-11-05 |url-status=dead}}</ref>