text:
Mandate

Mandate most often refers to:
 * League of Nations mandates, quasi-colonial territories established under Article 22 of the Covenant of the League of Nations, 28 June 1919
 * Mandate (politics), the power granted by an electorate

Mandate may also refer to:
 * Mandate (after shave), British after shave brand
 * Mandate (criminal law), an official or authoritative command; an order or injunction
 * Mandate (international law), an obligation handed down by an inter-governmental body
 * Mandate (magazine), a monthly gay pornographic magazine
 * Mandate (trade union), a trade union in Ireland
 * HMS Mandate, various ships of Britain's navy
 * Mandate (typeface), a brash-brush typeface designed by R. Hunter Middleton
 * The formal notice of decision from an appeals court
 * A requirement for a Health maintenance organization to provide a particular product

title: Mandate


text:
Privy Council Office (United Kingdom)

The Privy Council Office (PCO) provides secretariat and administrative support to the Lord President of the Council in his or her capacity as president of His Majesty's Most Honourable Privy Council. The head of the office is the Clerk of the Privy Council. The PCO is an independent unit based in the Cabinet Office.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Privy Council Office (United Kingdom)


text:
Jean Léonard Marie Poiseuille

Jean Léonard Marie Poiseuille (22 April 1797 – 26 December 1869) was a French physicist and physiologist.

Poiseuille was born in Paris, France, and he died there on 26 December 1869.

Fluid flow
From 1815 to 1816 he studied at the École Polytechnique in Paris. He was trained in physics and mathematics. In 1828 he earned his D.Sc. degree with a dissertation entitled Recherches sur la force du coeur aortique (The force of the aortic heart). He was interested in the flow of human blood in narrow tubes, and invented the U-tube mercury manometer (or hemodynamometer) to measure arterial blood pressures in horses and dogs.

In 1838 he experimentally derived, and in 1840 and 1846 formulated and published, Poiseuille's law (now commonly known as the Hagen–Poiseuille equation, crediting Gotthilf Hagen as well), which applies to laminar flow, that is, non-turbulent flow of liquids through pipes of uniform section, such as blood flow in capillaries and veins. The poise, the unit of viscosity in the CGS system, was named after him.

title: Jean Léonard Marie Poiseuille


text:
Talk:List of passenger trains

Need to make clear -- are these famous physical trains, ie an engine, or a famous train route?
 * It seems to be primarily routes, as the summary says. It's totally inconsistent though, as the Shinkansen is included (a type of train, not a route necessarily), but the TGV is not.  I'd think the TGV is much more famous than the Intercity 125, which is included.   This type of article is always going to be problematic on Wikipedia Jpp42 09:27, 5 November 2007 (UTC)

 * Surely entries like Mallard would be more appropriately shown in the famous locomotives category? Or how about a famous locomotives list?  I'm not sure about the Bullet train or TGV, though. Nsorelli 13:16, 5 November 2007 (UTC)

There are also some famous trains in Asia; i.e. Darjeeling Mountain Train (the oldest working steam trains in operation; Darjeeling, India) and The Eastern and Oriental Express (between Singapore and Chiang Mai via Bangkok). I also believe that there is another tain that runs from Dehli to Kabul that is world famous.

Famous trains - yellow train
I would like to add a little section about the Yellow train, or yellow canary. This train is in the South Eact of France, just north of the Spanish border. The track is a relatively short run, just 63 kilometres.But it climbs from very close to sea level to nearly 1600 metres. The line was built in 1903 and it is a very dramatic and enjoyable journey. Would appreciate any thoughts on the value of this addition Collieman
 * The article on Yellow Train is pretty short - maybe you could help to expand it? And what makes this train "famous" - this is a much higher standard than "notability" keep in mind.  There really should only be a few famous trains. Jpp42 09:27, 5 November 2007 (UTC)

What about Trotsky's armored train during the Civil War?
 * Is there an article about this on Wikipedia yet? Jpp42 09:27, 5 November 2007 (UTC)

Famous trains - or historical?
The title of this page has been changed from famous trains list to historical trains on the grounds that it is less subjective. I'm not sure that's right, but I think use of the word historical (that is, belonging to the past, not the present) is incorrect. Many of these trains still run and indeed, like Eurostar, are recent additions. I agree we can argue about whether a particular train is famous or not, so perhaps notable is a more appropriate if less impressive title. Personally I'd be happier with famous. Anybody else care? Nsorelli 05:58, 13 November 2007 (UTC)
 * The naming conventions state that titles shouldn't use subjective words like "famous" or "notable", and articles that are called "List of famous X" are frequently deleted for being subjective. Historical may not be the most accurate title, so if you or anyone else has any suggestions, as long as they don't use "famous", "notable", "noted", "significant", or "important". Masaruemoto 05:55, 14 November 2007 (UTC)

 * I think "historical" dramatically broadens the scope of the article - almost to the point of uselessness. Sure, "famous" has a degree of subjectivity to it, but we can probably source comments attesting to the train's fame in comparison to other services.  There's no way I could sneak something like the Culverden Express into the article - a train so poorly known that even books on New Zealand railways mention it in passing while giving just about every other express substantially more attention.  However, the Culverden Express is quite legitimately a "historical" train.  And if it could be put on here, so could any other historical service and it would quickly become a sprawling list .  Worse still, it would be barely distinct from List of named passenger trains and a merge would probably be justified. - Axver 06:12, 14 November 2007 (UTC)

 * I'll revert it back to the former name then, although the list criteria itself seems subjective as well. The advantage that List of named passenger trains has is the title clearly defines the contents, which is important in list naming. Masaruemoto 07:58, 15 November 2007 (UTC)

Sentence makes very little sense
"rail travel was the predominant means of transportation for long-distance travel - and was therefore most common only for the wealthy or those with an urgent personal or business need."

The preceding sentence makes very little sense. What it the intended meaning ? It appears to be a complete non sequitur to me. During the 1860-1960 heyday of rail transport, it was indeed the predominant means of transport. How is therefore causative of being most common only for the wealthy or on urgent business ? Is the author of this sentence trying to imply that the poor did not generally travel at all,  or that they used other means of transport ? Eregli bob (talk) 06:04, 27 January 2008 (UTC)

 * I agree with you, it's a ridiculous assertion; railroads were the Interstate Highway system of the time, everybody traveled on them. So I deleted the sentence; then I realized the rest of the statements in that paragraph were also wrong or misleading, and had no real bearing on the topic of this article, so I deleted all but the first sentence.  It's a silly article to begin with, because there are no stated criteria from reputable sources to define "famous trains"; the whole article really should be deleted, imho.  Textorus (talk) 02:24, 19 August 2008 (UTC)

Proposed deletion
I thought it over, and I can't see any justification for keeping this article alive. It was started as a list of only four trains in 2003, and since then, it seems, folks have just been adding to the list according to their whimsy. But NOBODY has provided any verification by reputable sources for their listings - and what exactly is the definition of "famous train," anyway? - so it appears to be just a vanity list of "my favorite trains." Anyone disagree? Textorus (talk) 02:41, 19 August 2008 (UTC)

 * I'm not sure deletion is necessarily the answer here, although the inclusion criteria are completely arbitrary. Perhaps it would make sense to redirect it to Lists of named passenger trains, and at least preserve the article history.  A good number of the entries are notable in one way or another.  --RFBailey (talk) 03:05, 19 August 2008 (UTC)

 * I like RFBailey's idea much better. DanTD (talk) 04:28, 19 August 2008 (UTC)

 * But what exactly is there worth saving in this article?? The trains that already have their own articles are covered there; they are (or should be, I haven't checked) also already be listed in the List of named passenger trains article; and the trains here that have no articles are just names with little or no information provided.  So what purpose does this list serve?  What exactly does it tell us about these particular trains?  Other than that somebody, somewhere thinks they are noteworthy....but every train in the world is "famous" to someone. This is a vanity list, pure and simple.

 * And again, there is no verified source for the noteworthiness of any of these trains. As it says at Lists, "Lists, whether they are embedded lists or stand-alone lists, are encyclopedic content as are paragraphs and articles, and they are equally subject to Wikipedia's content policies such as Verifiability, No original research, Neutral point of view, and others." Textorus (talk) 05:20, 19 August 2008 (UTC)

 * Textorus makes some good points, but his emotionality causes me problems. His statement that "This is a vanity list ..." is not acceptable language for a Wikipedian. He says this on two occasions, why? I think the content of the list should be checked to ensure that the information is present on other pages, else it should be treated in the sensible way that RFBailey states. Olana North (talk) 07:20, 19 August 2008 (UTC)

 * Instead of an ad hominem attack, Olana, wouldn't it be more constructive and more in keeping with the spirit of Wikipedia to address the specific questions I've raised, based on specific Wikipedia policies, as quoted above? Textorus (talk) 19:06, 19 August 2008 (UTC)

 * Textorus, Olana North, please try not to escalate the situation. (However, I do get the impression that this nomination has a touch of WP:IDONTLIKEIT about it.)  Now, as I see it, many of the entries on the list have articles about them, so that suggests that they are notable (to some people, at least).  Most of the entries are about named passenger trains (i.e. particular services); however, some seem to be about types of rolling stock, or operators.  This confusion is one of the problems that this article has; i.e. people are unclear what the scope of the list is, or don't understand the distinction between the two, which makes it look a bit like indiscriminate information.  So, if we were to remove those rogue entries and focus it entirely on named passenger trains, then at least it would be consistent.  But we already have Lists of named passenger trains which does that job.  Hence we can redirect this article to there.  Any entries on this list that are not already present on that (or rather, on its sub-lists) can be added if necessary, with citations.  As I mentioned above, this would have the advantage of retaining the article history so that non-admin editors can go back and have a look.

 * As pretty much everyone here (myself, Olana North, DanTD and Slambo) seems in favour of this approach, if there are no objections by some time tomorrow I'll go ahead with it. --RFBailey (talk) 23:05, 19 August 2008 (UTC)

 * Sounds like a sensible suggestion to me as well. DrFrench (talk) 23:36, 19 August 2008 (UTC)

 * Merge into List of named passenger trains. All of the trains listed on this article have names, therefore, they should all be included in the main list.  Slambo (Speak)  11:09, 19 August 2008 (UTC)

 * I have removed the prod taqg, as what seems to be under discussion is a merge. But Ihave a question---given the complexity ad division of the main list, how would someone get a chronological list of the most famous passenger trains? This relativelyu crude page would do it--the more complicated list (s) don't seem to. DGG (talk) 03:17, 20 August 2008 (UTC)

 * I'm not sure there would be much demand for such a list. What do others think?  --RFBailey (talk) 04:03, 20 August 2008 (UTC)

 * Maybe information on the most well-known or seminal trains should be added to Timeline of railway history as well. Slambo (Speak)  11:19, 20 August 2008 (UTC)

Redirect in place
OK, so I've gone ahead and merged as much information as I could find sensible homes for into the sub-lists of Lists of named passenger trains. (Those lists were something of a mess themselves, but that's a topic for another talk page.) I didn't merge anything about rolling stock, train operators, railway lines (i.e. stretches of track) or anything without an article. --RFBailey (talk) 03:14, 22 August 2008 (UTC)

 * Some of the Belgian trains are missing from the European list. I haven't checked any of the ones for other countries, like South Africa or New Zealand yet. DanTD (talk) 12:27, 22 August 2008 (UTC)

 * Well, there may have been some I overlooked, for which I apologise. Perhaps you could add them?  --RFBailey (talk) 13:28, 22 August 2008 (UTC)

title: Talk:List of passenger trains


text:
Arthur Ransome

Arthur Michell Ransome (18 January 1884 – 3 June 1967) was an English author and journalist. He is best known for writing and illustrating the Swallows and Amazons series of children's books about the school-holiday adventures of children, mostly in the Lake District and the Norfolk Broads. The entire series remains in print, and Swallows and Amazons is the basis for a tourist industry around Windermere and Coniston Water, the two lakes Ransome adapted as his fictional North Country lake.

He also wrote about the literary life of London, and about Russia before, during, and after the revolutions of 1917. His connection with the leaders of the Revolution led to him providing information to the Secret Intelligence Service, while he was also suspected by MI5 of being a Soviet spy.

Early life
Ransome was the son of Cyril Ransome (1851–1897) and his wife Edith Ransome (née Baker Boulton) (1862–1944). Arthur was the eldest of four children: he had two sisters Cecily and Joyce, and a brother Geoffrey who was killed in the First World War in 1918. Joyce married into the Lupton family, well-connected industrialists and politicians; she named one of her sons Arthur Ralph Ransome Lupton (1924–2009).

Ransome was born in Leeds; the house at 6 Ash Grove, in the Hyde Park area, has a blue plaque beside the door commemorating his birthplace. Ransome's father was professor of history at Yorkshire College (now the University of Leeds). The family regularly holidayed at Nibthwaite in the Lake District, and he was carried up to the top of Coniston Old Man as an infant. His father's premature death in 1897 had a lasting effect on him. His mother did not want him to abandon his studies for writing, but was later supportive of his books. She urged him to publish The Picts and the Martyrs in 1943, although his second wife Evgenia hated it, and was often discouraging about his books while he was writing them.

Ransome was educated first in Windermere and then at Rugby School (where he lived in the same study room that had been used by Lewis Carroll) but did not entirely enjoy the experience, because of his poor eyesight, lack of athletic skill, and limited academic achievement. He studied chemistry at Yorkshire College, where his late father had worked.

Writing career
After a year at Yorkshire College, he abandoned his studies and went to London to become a writer. He took low-paying jobs as an office assistant in a publishing company and as editor of a failing magazine, Temple Bar Magazine, while establishing himself as a member of the literary scene.

Some of Ransome's early works were The Nature Books for Children, a series of children's books commissioned by Anthony Treherne. Only three of the six planned volumes were published before the publisher went bankrupt. They are available on the All Things Ransome website.

In his first important book, Bohemia in London (1907), Ransome introduced the history of the city's Bohemian literary and artistic communities and some of its current representatives. A curiosity in 1903 about a visiting Japanese poet, Yone Noguchi, led to an ongoing friendship with Japanese painter (and Chelsea neighbour) Yoshio Markino, who in turn introduced him to the Bohemian circle of Pamela Colman Smith, an artist best known for illustrating the Rider–Waite tarot deck.

Ransome married Ivy Constance Walker in 1909 and they had one daughter, Tabitha. It was not a happy marriage; Ransome found his wife's demands to spend less time on writing and more with her and their daughter a great strain; his biographer Hugh Brogan writes that "it was impossible to be a good husband to Ivy". They divorced in 1924.

Ransome began writing books of biography and literary criticism on various authors; one on Edgar Allan Poe was published in 1910 and another on Oscar Wilde in 1912. However, the latter embroiled him in a libel suit with Lord Alfred Douglas. His wife attended the 1913 trial, sitting in the public gallery as Ransome would not let her sit beside him. Her apparent enjoyment of the public notoriety the case attracted added to the stress on their marriage. The publisher Daniel Macmillan dined with the couple every day during the trial so that Ivy could not quarrel with Arthur. Ransome won the suit, supported by Robbie Ross, the editor of De Profundis. Douglas was bankrupted by the failed libel suit. Ransome did, however, remove the offending passages from the second edition of his book and refused all interviews, despite the obvious publicity value.

Adding to Ransome's "wretched" 13 months waiting for the case to come to trial was the action of his publisher, Charles Granville. Oscar Wilde, a critical study had been prepared under the guidance of publisher Martin Secker, but Granville had promised better returns and a guaranteed and steady income. Secker agreed to release the rights, and Ransome handed Poe and Wilde over to Granville. The work on Wilde was well received and successful, running to eight editions, but Ransome saw little in return; in 1912 Granville was charged with embezzlement and fled the country, leaving Ransome to struggle even to register himself as a creditor of Granville's ruined company. Furthermore, his neglect of his health (he suffered from piles and a stomach ulcer) had been exacerbated by the pressure of defending the legal action. Ransome had also been working on a similar literary biography of Robert Louis Stevenson, but that was abandoned with the manuscript in the first draft and not rediscovered until 1999. It was subsequently edited and finally published almost a century later in 2011 as Arthur Ransome's Long-lost Study of Robert Louis Stevenson.

As an enthusiast for detective fiction, between 1939 and 1940 Ransome contributed to The Observer as a reviewer of new detective novels, using the pen-name of William Blunt.

Foreign correspondent
In 1913 Ransome left his first wife and daughter and went to Russia to study its folklore. In 1915, Ransome published The Elixir of Life (published by Methuen, London), which was to be his only full-length novel apart from the Swallows and Amazons series. It is a gothic romance concerning a youth who chances upon an alchemist who has discovered the titular elixir of life, whose powers must be renewed by the spilling of human blood. He published Old Peter's Russian Tales, a collection of 21 folktales from Russia, the following year.

After the start of the First World War, in 1914, he became a foreign correspondent and covered the war on the Eastern Front for a radical newspaper, The Daily News. He also covered the Russian Revolutions of 1917 and came to sympathise with the Bolshevik cause, becoming personally close to a number of its leaders, including Vladimir Lenin, Leon Trotsky and Karl Radek. He met the woman who would become his second wife, Evgenia Petrovna Shelepina, who then worked as Trotsky's personal secretary.

Ransome provided some information to British officials and the British Secret Intelligence Service, which gave him the code name S.76 in their files. Bruce Lockhart said in his memoirs: "Ransome was a Don Quixote with a walrus moustache, a sentimentalist who could always be relied upon to champion the underdog, and a visionary whose imagination had been fired by the revolution. He was on excellent terms with the Bolsheviks and frequently brought us information of the greatest value." Nonetheless, in March 1919, on one of his return visits to the United Kingdom, the authorities interviewed him and threatened him with exposure as an agent. In October 1919, Ransome met Reginald Leeper of the Foreign Office's Political Intelligence Department, who required Ransome privately to submit his articles and public speaking engagements for approval. Ransome's response was "indignant". Unbeknown to Leeper, Ransome's "near treason[ous]" articles were written to buttress his exceptional access to the Bolshevik leadership. MI5, the British Security Service, was suspicious that Ransome and his fellow journalist, M. Philips Price, were a threat because of their opposition to the Allied Intervention in the Russian Civil War.

In October 1919, as Ransome was returning to Moscow on behalf of The Manchester Guardian, the Estonian foreign minister Ants Piip entrusted him to deliver a secret armistice proposal to the Bolsheviks. At that time, the Estonians were fighting their War of Independence alongside the White movement of counter-revolutionary forces. After crossing the battle lines on foot, Ransome passed the message, which, to preserve secrecy, had not been written down and depended for its authority only on the high personal regard in which he was held in both countries, to diplomat Maxim Litvinov in Moscow. To deliver the reply, which accepted Piip's conditions for peace, Ransome had to return by the same risky means, but now, he had Evgenia with him. Estonia withdrew from the conflict, and Ransome and Evgenia set up home together in the capital Tallinn.

After the Allied intervention, Ransome remained in the Baltic states and built a cruising yacht, Racundra. He wrote a successful book about his experiences, Racundra's First Cruise. He joined the staff of The Manchester Guardian when he returned to Russia and the Baltic states. Following his divorce, he married Evgenia and brought her to live in England, where he continued writing for The Guardian, often on foreign affairs, and also writing the "Country Diary" column on fishing. On the Ransomes' return to England, Racundra was sold to the yachting author Kaines Adlard Coles, who sailed her back to England.

Swallows and Amazons series
By the late 1920s, Ransome had settled in the Lake District because he had decided not to accept a position as a full-time foreign correspondent with The Guardian newspaper. Instead he wrote Swallows and Amazons in 1929 – the first of the series that made his reputation as one of the best English writers of children's books.

Ransome apparently based the Walker children (the "Swallows") in the book partly on the Altounyan family. He had a long-standing friendship with the mother of the Altounyans, and their Collingwood grandparents. Later, he denied the connection, claiming he simply gave the Altounyans' names to his own characters; it appears to have upset him that people did not regard the characters as original creations. Letters also indicate that conflict arose between Ransome and the family.

Ransome's writing is noted for his detailed descriptions of activities. Although he used many actual features from the Lake District landscape, he invented his own geography, mixing descriptions of different places to create his own juxtapositions. His move to East Anglia brought a change of location for four of the books, and Ransome started using the real landscape and geography of East Anglia, so that one can use the maps printed in the books as a guide to the real area. Ransome's own interest in sailing and his need to provide an accurate description caused him to undertake a voyage across the North Sea to Flushing in the Netherlands. His book We Didn't Mean To Go To Sea reflects that, and he based the fictional Goblin on his own boat Nancy Blackett (which in turn took its name from a character in the series).

Two or three of the Swallows and Amazons books have less realistic plots. The original concept of Peter Duck was a story made up by the children themselves, and Peter Duck had appeared in the preceding volume, Swallowdale, as a character whom the children created, but Ransome dropped the foreword of explanation from Peter Duck before it was published. Although relatively straightforward, the story, together with its equally unrealistic ostensible sequel Missee Lee, is much more fantastic than the rest of the series. A trip to China as a foreign correspondent provided Ransome with the imaginative springboard for Missee Lee, in which readers find the Swallows and the Amazons sailing around the world in the schooner Wild Cat from Peter Duck. Together with Captain Flint (the Amazons' uncle Jim Turner), they become the captives of Chinese pirates.

Peter Duck was illustrated by Ransome himself using pen and ink, although the frontispiece claims that the book is "Based on information supplied by the Swallows and Amazons and illustrated mainly by Themselves." Ransome then continued to illustrate the stories, and provided illustrations for new editions of the first two books of the series as of 1938, replacing images by Clifford Webb (whose illustrations for Swallows and Amazons had themselves replaced Steven Spurrier's first edition drawings. Ransome had disliked Spurrier's images and only the maps drawn by Spurrier were retained for the end paper and dust jacket).

The final book of the series, Great Northern? (1947) was set in Scotland, and while the plot and action appear realistic, the internal chronology does not fit the usual run of school holiday adventures. Myles North, an admirer of Ransome, provided much of the basic plot of the book.

Swallows and Amazons was so popular that it inspired a number of other authors to write in a similar vein. Most notably, two schoolchildren, Pamela Whitlock and Katharine Hull, wrote The Far-Distant Oxus, an adventure story set on Exmoor. Whitlock sent the manuscript to Ransome in March 1937, and he persuaded his publisher, Jonathan Cape, to produce it, characterising it as "the best children's book of 1937".

Sailing
After the sale of Racundra in 1925 (in Coles' ownership she became Annette II), Ransome went on (in addition to the occasional charter, loan or trial sail) to own five further cruising yachts. His next yacht was the Hillyard-built Nancy Blackett, which he owned from 1935 to 1938. She was originally named Spindrift when launched in 1931.

After this came Selina King, a 35 ft 12 ton cutter with a canoe stern, designed by Frederick Shepherd and built at Harry Kings Yard in Pin Mill in 1938. She was laid up during the war and (on medical advice) they sold her in 1946.

After the war, he commissioned a ketch from Laurent Giles, again built in Pin Mill by Harry King: Peter Duck. He owned her from 1947 to 1949; her design was the basis for a class of which over 40 were built.

In July, 1951, he saw Norvad, a Hillyard five-and-a-half ton centre-cockpit yacht. With Evgenia, he had a trial sail in Norvad the following month in a hard offshore wind. They decided to get one, which he had decided should bear the name Lottie Blossom, and put in an order for that year's Boat Show model. With a list of things they wanted done to modify the boat below decks from the standard production model, the boat was launched on 1 April 1952. Ransome's health problems delayed their first sail to 15 April. In December 1952, he sold Lottie Blossom to Sir William Paul Mallinson on condition that he (Ransome) retained the name.

Lottie Blossom II followed early the next year, using the same design of hull, but with aft cockpit and tiller steering. They had two very happy seasons in her, sailing her comfortably on their own, including two voyages to Cherbourg. The second voyage, in 1954, at the age of 70, was to be Ransome's last long passage.

Personal life
Ransome married twice, first to Ivy Constance Walker in 1909, with whom he had a daughter, Tabitha Ransome; the couple divorced in 1924. His second marriage, that same year, was to Evgenia Petrovna Shelepina. Although MI5 appeared satisfied with Ransome's loyalty to Britain by 1937, KGB files that were opened following the end of the Soviet Union suggest that Evgenia Ransome, at least, was involved in smuggling diamonds from the USSR to Paris to help fund the Comintern. This is examined in the 2009 book The Last Englishman: the Double Life of Arthur Ransome by Roland Chambers. Ransome and his second wife are buried in the same grave.

Death
Ransome died in Cheadle Royal Hospital on 3 June 1967. He and his wife Evgenia are buried in the churchyard of St Paul's Church, Rusland, Cumbria, in the southern Lake District. The Autobiography of Arthur Ransome, edited by Rupert Hart-Davis, was published posthumously in 1976. It covers his life only to the completion of Peter Duck in 1931.

Awards and accolades
Ransome won the inaugural Carnegie Medal from the Library Association, recognising Pigeon Post in the Swallows and Amazons series as the year's best children's book by a British subject. He was appointed CBE in 1953. Durham University made him an honorary Master of Arts (which he told Cape to ignore) and Leeds University made him an honorary Doctor of Letters in 1952.

Translations of his books have been published in several languages and he became popular in many countries. Thriving Ransome appreciation societies exist in the Czech Republic, and in Japan where the Arthur Ransome Club was founded in 1987. Czech astronomer Antonín Mrkos named an asteroid after the author (6440 Ransome). The Arthur Ransome Society founded in 1990 in the U.K. now has a worldwide membership.

Works

 * The Souls of the Streets and other Little Papers (1904)
 * The Child's Book of the Seasons (1906)
 * Pond and Stream (1906)
 * The Things in our Garden (1906)
 * Bohemia in London (1907)
 * The Book of Friendship (1909)
 * A History of Story-telling (1909)
 * Edgar Allan Poe (1910)
 * The Book of Love (1911)
 * The Hoofmarks of the Faun (1911)
 * Oscar Wilde, a Critical Study (1912)
 * Portraits and Speculations (1913)
 * The Elixir of Life (1915)
 * Old Peter's Russian Tales (1916)
 * A Letter to America (1918)
 * Six Weeks in Russia (1919)
 * Aladdin and his Wonderful Lamp in rhyme (1920)
 * The Crisis in Russia (1921)
 * The Soldier and Death (1922)
 * Racundra's First Cruise (1923)
 * The Chinese Puzzle (1927)
 * Rod and Line (1929)
 * Mainly about Fishing (1959)

"Swallows and Amazons" series

 * Swallows and Amazons (published 1930)
 * Swallowdale (1931)
 * Peter Duck (1932)
 * Winter Holiday (1933)
 * Coot Club (1934)
 * Pigeon Post (1936)
 * We Didn't Mean To Go To Sea (1937)
 * Secret Water (1939)
 * The Big Six (1940)
 * Missee Lee (1941)
 * The Picts and the Martyrs: Or Not Welcome at All (1943)
 * Great Northern? (1947)
 * Coots in the North (unfinished) —Ransome died in 1967 and the work was edited by Hugh Brogan and sections published as unfinished in 1988, with some other short works.

Published posthumously

 * Racundra's third cruise (1972) (edited by Brian Hammett)
 * The Autobiography of Arthur Ransome (1976) (edited by Rupert Hart-Davis)
 * The War of the Birds and Beasts and other Russian tales (1984) (edited by Hugh Brogan)
 * Arthur Ransome On Fishing (1994) (edited by Jeremy Swift)
 * Arthur Ransome's Long-lost Study of Robert Louis Stevenson (2011) (edited by Kirsty Nichol Findlay)

title: Arthur Ransome


text:
Talk:Ellipse

Finding the foci and directrices geometrically

Here are some ways to find the focus (point F) and directrix (line through D) using compass and straight edge. Didn't see them mentioned in the article. I would create an animation but my software is not that good. ➧ datumizer   ☎  10:47, 2 March 2021 (UTC)

 * Your method is just a variation of the method shown in the picture of subsection "standard equation" and the fact, that a directrix and the corresponding focus are a pair pole-polar.--Ag2gaeh (talk) 13:21, 2 March 2021 (UTC)
 * Maybe I am looking at the wrong image? I don't see any similarity. ➧ datumizer   ☎  20:45, 3 March 2021 (UTC)
 * The article says, "C2 is called the circular directrix (related to focus {\displaystyle F_{2}}F_{2}) of the ellipse.[1][2] This property should not be confused with the definition of an ellipse using a directrix line below." So the two images describe different things. ➧ datumizer   ☎  21:30, 3 March 2021 (UTC)

I mentioned the picture in subsection "standard equation". Any construction of a focus uses the equation $$a^2=b^2+c^2$$ and a right angular triangle, Yours too. Your construction of one point of the directrix line is based on the fact, that the points $$(c,0), (\tfrac{a^2}{c},0)$$ are inverse with respect to circle $$x^2+y^2=a^2$$. This is equivalent to a pole-polar relation (see section of this article) with respect of this circle.--Ag2gaeh (talk) 08:06, 4 March 2021 (UTC)

 * The image doesn't actually show how to plot the points geometrically though. Yeah it is possible to infer this. But is it maybe better to show instead of tell? Or is there a length limit on Wikipedia articles? ➧  datumizer   ☎  05:31, 6 March 2021 (UTC)

 * If You agree, I add Your picture to section "pole-polar relation". But, it would be suitable to cut off not necessary parts and to add the lines containing the main axes. The usual construction of focus F (see picture) is more easy, so You should concentrate on the construction of point D and the directrix (orthogonal to line OD). --Ag2gaeh (talk) 08:48, 6 March 2021 (UTC)

 * What parts are unnecessary? I don't understand. I have created a similar image for the hyperbola (see to the right) and would like to keep as many elements as possible the same between them. I also can create two separate sets of images for the ellipse and hyperbola: one set for constructing the focus, another set for constructing the directrix. ➧ datumizer   ☎  06:00, 8 March 2021 (UTC)

With "unnecessary" I meant just "white space" to shrink the picture a little. For the hyperbola it is the same game: F and D are inverse with respect of the green circle. In both cases You should add the lines of the great main axis, on which the points F,D,A lie. Please insert Your pictures together with some explanations in a suitable subsection.--Ag2gaeh (talk) 14:34, 8 March 2021 (UTC)

Article is difficult to understand
This article is very difficult to understand. It seems to be written by mathematicians for mathematicians, on the basis that nobody else needs to understand it. (Or perhaps the people who wrote it copied from books by mathematicians, but could not explain it simply because the editors did not understand it.)
 * Analytically, the equation of a standard ellipse centered at the origin with width $$2a$$ and height $$2b$$ is:
 * $$\frac{x^2}{a^2}+\frac{y^2}{b^2} = 1 .$$

It says what a and b are. But it leaves x and y undefined.

The lead needs to explain simple concepts in simple language. When concepts such a focal points (focii) are introduced they need to be explained clearly. Equations should have their terms defined. -- Toddy1 (talk) 11:29, 6 August 2021 (UTC)

Note on the above: x and y are the most common axes in Cartesian coordinate geometry, and their nature of up/down and left/right applies here as well. You do not need to be a mathematician to understand it, but you do need early secondary school mathematics. I agree that it would be nice if the axes were labelled, but it's a very safe assumption in the absence of other data.

However, as an engineer, I find that the most common use of the pronumeral 't' regarding conic sections is for time. As such, the section on #Parametric_representation was slow to decipher. Is it acceptable to change the pronumeral to 'phi' or similar, to acknowledge that this is not the common angle 'theta', but a different angular variable? JAyerson (talk) 09:30, 23 February 2022 (UTC)

Error in formula for 'F' - the intercept in terms of semimajor and semiminor?
Formula reads

$$ F = A x_0^2 + B x_0 y_0 + C y_0^2 + a^2 b^2 $$

But the a and b here are different from the a and b in the other equations - they should be doubled, no? I found the formula to end with $$ 4 a^2 b^2 $$. — Preceding unsigned comment added by 88.109.89.43 (talk) 23:21, 23 August 2021 (UTC)

Proposed change
''The section In Cartesian coordinates seems to be assuming b² = a² - c² without proving it. Should it be replaced with:''

Ellipse as conic section

Let the ellipse be centered at origin with directrix x = k, semi-major axis a, semi-minor axis b, eccentricity e and the focus at (c,0).

From the definition of conic section,

$$\sqrt{(x - c)^2 +y^2} = e(k - x)$$

At (a, 0), $$a - c = e(k - a)$$

At (-a, 0), $$a + c = e(k + a)$$

These yield $$a = ek$$ and $$c = ae = e^2k$$

At (0, b), $$\sqrt{c^2 +b^2} =ek$$

Or, $$b^2 =a^2(1-e^2)$$

Plugging back and squaring,

$$x^2 + e^4 k^2 - 2e^2kx + y^2 = e^2(k^2 +x^2 - 2kx)$$

$$x^2(1 - e^2) + y^2 = e^2 k^2(1-e^2)$$

$$\frac{x^2}{a^2}+\frac{y^2}{b^2} = 1 $$

Shubjt (talk) 06:20, 30 November 2021 (UTC)
 * No, we do not need to derive the Pythagorean theorem here. Readers can be expected to know it and a proof is off-topic. —David Eppstein (talk) 08:19, 30 November 2021 (UTC)

 * I mean it isn't proven that the distance between covertex and focus is equal to the semi-major axis. Shubjt (talk) 13:59, 30 November 2021 (UTC)

 * Please, look at the diagram and the definition of an ellipse ! --Ag2gaeh (talk) 15:26, 30 November 2021 (UTC)

parameter in elliptic integral is negative???
In the section entitled "Arc length", E{z,1-a^2/b^2} is compared to E{z,m}, where m=k^2. Because a > b, 1-a^2/b^2 <0, which would require purely imaginary k??? I think something is wrong there... — Preceding unsigned comment added by 2A02:908:1C10:F8C0:2933:DA59:F60:5BDE (talk) 19:51, 13 March 2022 (UTC)

 * $$k$$ is purely imaginary, but there's nothing wrong with that. See e.g. https://dlmf.nist.gov/19.7.E5 (Imaginary-Modulus Transformation). Also $$k\in i\mathbb{R}$$ is just a matter of flipping the sign in $\operatorname{E}(\varphi,k)=\int_0^\varphi\sqrt{1-k^2 \sin^2\theta}\, \mathrm d\theta$, so you "work with" real quantities anyway. A1E6 (talk) 20:06, 13 March 2022 (UTC)

Umfang der Ellipse: Annäherungsformel
the most easiest derivation for calculating the circumference of the ellipse you find in the apendix and leads to my new formula, which uses the "YNOT" constant: All "YNOT"-formulas: first formula: P ≈ 4 (a^y + b^y)^(1/y)  for   y=ln (2) / ln (pi/2) = 1.5349285.... (YNOT constant) the second is my formula: P ≈ 4a(1 + (b/a)^y)^(1/y) and the third is: P ≈ 4a(1 + (1-e²)^(y/2))^(1/y) These three formulas lead to the same result. In my opinion all of these three fomulas should be published in wikipedia. The most simple derivation of the astroid approximation for the circumference of the ellipse:

If you want to find out a formula of approximation for the circumference of the ellipse now, you need an elementary function, which proceeds as exact as possible on the frequency polygon. The frequency polygon develops when a' as x and b' as y of the ellipses which all have the circumference C=2pi are stripped of. By comparing this formula with other elementary formulas, you will recognize the similarity of the frequency polygon with an outside curved “bugly astroid”. The general formula of the astroid with a length of the branch of the astroid of π/2 is: y=((π/2)^z - x^z)^(1/z)            at which the “kurtosis“  is determined by z.

If you search the special astroid, which proceeds through the point (1/1), the kurtosis z must be ascertained at which the function y takes the value 1 although x=1. You get the value „bex“ for the kurtosis by inserting the values and solving to “Y”: 1=((π/2)^y - 1^y )^(1/y)     ->    1^y=((π/2)^y - 1^y)) ->    1^y=(π/2)^y - 1^y   ->     2^y=(π/2)^y  -> ln(2) = y * ln(π/2)    ->    y =  ln(2)/ ln(π/2)    ->    y = 1,5349285…  = konstant  The equation for the astroid then is: f(x)=((π/2)^y - x^y)^(1/y)      because    (π/2)^y  = 2  you get f(x)=(2-x^y )^(1/y)      This is a nice elementary provisional result. The line  f(x) = b/a x strips on  the whole length the ratio of b/a If you equalize the both equations, in the intersection you get the x- and  the y-value for the desired ratio for b/a  of the  given ellipse. The formulas  are: astroid-formula             =       line-formula f(x)=((π/2)^y - x^y )^(1/y) =        b/(a ) x

(π/2)^y - x^y              =        (b/a)^y x^y

(π/2)^y                  =        (b/a)^y x^y + x^y

(π/2)^y                  =        x^y ( (b/a)^y+1 )

x^y                      =        (π/2)^y/((b/a)^y+1) x                        =        (((π/2)^y / ((b/a)^y+1 )))^(1/y)   =    a' f(x)                      = b/a * a'                                  =    b'

The values for x and f(x) are a` and b`of the ellipse with the U = 2π at the same time. The circumference of the searched ellipse results by U = 2π a/a`. By inserting of a’ results: U = 2π a /(( (π/2)^y  /  ( (b/a)^y+1 )))^(1/y) =   2π a /  π/2  / ((( (b/a)^y+1 )))^(1/y)

By reducing results: U ≈ 4 a (((b/a))^y+1)^(1/y)        for  the 2. solution you have to change a and b: U ≈ 4 b (((a/b))^y+1)^(1/y) as second „Y-NOT“-circumference-formula for the ellipse with a relative deviation of max. 1,54%. quod erat demonstrandum

Greetings

Jürgen Beck, Germany Becksjuergen (talk) 17:27, 13 June 2022 (UTC)

 * Thanks for your efforts, but Wikipedia is not a venue to spread original research, see WP:NOR. - MrOllie (talk) 18:10, 13 June 2022 (UTC)

General ellipse formulas
I consulted one of the sources referenced for the General ellipse but could not find those formulas. In particular I'm concerned with the formula for the cotangent of the angle $$\theta$$. Is it possible there are additional solutions, or that there are typos in a couple of signs? I'm referring to the first case of the last equation, for which during verification I obtain the following:

$$\theta = \arccot\dfrac{-C + A -\sqrt{(A-C)^2+B^2}}B $$

rather than

$$\theta = \arccot\dfrac{C - A -\sqrt{(A-C)^2+B^2}}B $$

--Gciriani (talk) 16:01, 25 May 2023 (UTC)
 * This additional link shows a much simpler equation, which gives results in agreement with my numerical calculations.

$$tan(2\theta) = \dfrac{B}{A-C}, with {} 0<\theta <\pi/4 $$

--Gciriani (talk) 20:43, 25 May 2023 (UTC)

 * I think you want
 * $$2\theta = \operatorname{atan2}(-B, C-A),$$
 * where atan2 is the 2-argument arctangent. Or if you want to avoid that, you can instead do:

\theta = \arctan\left(\frac{-B}{\sqrt{(C-A)^{2}+B^{2}}+C-A}\right) = \arctan\left(\frac{\sqrt{(C-A)^{2}+B^{2}}-\left(C-A\right)}{-B}\right) $$
 * With the caveat that these can break down when $$B = 0$$ (see atan2 for details).
 * Here is a Desmos plot: https://www.desmos.com/calculator/3xjo0omput –jacobolus (t) 03:12, 26 May 2023 (UTC)
 * Thank you for simplifying the theta formula with atan2. Several years ago when I added this general -> canonical formula subsection, I originally had:
 * $$\theta = \arctan \frac{C - A - \sqrt{(A-C)^2 + B^2}}{B}$$
 * with special cases for 0 and 90 degrees. Various people changed the theta formula over time, leading to the contangent form with even more cases.  This atan2 form is much simpler.
 * Now I see another simplification. Looking at the canonical to general formulae above, it would appear that a and b should depend only on A, B, & C and not on D, E or F, and in fact, it's true.  If you substitute the equation for F into the a,b equation, then substitute the x0 and y0 equations and simplify, D and E fall out and you're left with only:
 * $$a,b = \sqrt{\frac{1}{2} \left(A + C \pm \sqrt{A^2 + B^2 + C^2 - 2 A C}\right)}$$.
 * I propose changing the formula to this. I'm surprised no one else noticed this or otherwise edited the a,b formula in all the time this has been up.
 * The one question I have is what to do with the reference. There is a reference to a Wolfram document that has similar (but not exactly the same) formulae to what I wrote containing D, E & F.  I don't know of a reference giving the simpler form.  Any ideas where to look? Pdx scooter (talk) 07:59, 11 January 2024 (UTC)
 * You'll want to double check your formula. This version gives numerically different answers than the previous version. –jacobolus (t) 00:36, 14 January 2024 (UTC)
 * Note that changing any of D, E, or F (translates and) scales the ellipse, which has the effect of also changing a and b. It's plausible that there's a clearer way to write the formula though. –jacobolus (t) 00:42, 14 January 2024 (UTC)
 * I see the problem -- it's that the general formula coefficients are not unique, as you can scale them all by an arbitrary non-zero real constant without changing the result. My original a,b formulae are invariant under scaling of all of the constants, but the proposed simpler versions are not.
 * What led me to proposing the alternate versions is that if you substitute them and the theta equation back into the A,B,C equations above, then use the half-angle cosine and sine functions: $$\{\cos^2, \sin^2\}\left(\tfrac12 \operatorname{atan2}{(u, x)}\right) = \tfrac12 (1 \pm \frac{x}{\sqrt{x^2 + y^2}})$$ to eliminate the trig functions then simplify, the A,B,C equations do reduce to A=A, B=B, and C=C. But that's assuming no scaling constant. Thanks again for your input. Pdx scooter (talk) 04:05, 14 January 2024 (UTC)
 * Feel free to use https://www.desmos.com/calculator/goocxro2gg to check these. –jacobolus (t) 00:46, 14 January 2024 (UTC)

Circumference
I like to point out to people who say that the circumference of an ellipse is hard to calculate the following:

There is a formula for circumference of an ellipse in form C=p(a/b)(a+b) where a & b are the semiaxis. The function p(a/b) has its minima when a=b and it's value then is pi. So p(a/b) is easy to calculate for every value as pi is for the case a=b. So in fact the circumference of an ellipse is as easy to calculate as the circumference of a circle. It's just that for the one special case the value of the function has been calculated, but everyone who knows something about series can get a powerseries for p(a/b) to calculate it's values. I always also demonstrate this by setting b=1 so the circumfence is C=p(a)(a+1). It is easy from this to see that p(a) has maximum when a=0 or infinite and then p(a)=4.

Linkato1 (talk) 09:37, 4 June 2023 (UTC)

 * Where do you get this? Where is the information necessary to derive a power series? —Tamfang (talk) 07:14, 24 June 2023 (UTC)
 * Take the first integral you see on the page for circumference. Substitute the e as expressed by a & b. Divide the integral by (a+b). Rearrange and you get an integral where the parameter is a/b or its inverse, this is p(a/b). Then just look up how integral can be set as a power series. Insert your integrand and you have your powerseries. Linkato1 (talk) 10:10, 29 June 2023 (UTC)

Focus-to-focus reflection property
The angle bisector theorem applies to a triangle and LQF_1 is not necessarily a straight line. It seems to me that the proof should be corrected by adding a point Q' such that LQ'F_1 is a straight line and then using the fact the PQ' is a bisector to claim the same ratio for QL/QF_1. Mba14 (talk) 06:16, 3 August 2023 (UTC)

 * If $$PL \cong PF_1,$$ then the angle bisector of $$\angle LPF_1$$ is the same as the perpendicular bisector of the segment $$LF_1.$$
 * Frankly, this proof (and some others on this page) is already more detailed than it needs to be for the purpose of a Wikipedia article of such broad scope. I would cut it to just:
 * Because the tangent line is perpendicular to the normal, an equivalent statement is that the tangent is the external angle bisector of the lines to the foci (see diagram).
 * Let $$L$$ be the point on the line $$\overline{PF_2}$$ with distance $$2a$$ to the focus $$F_2$$, where $$a$$ is the semi-major axis of the ellipse. Let line $$w$$ be the external angle bisector of the lines $$\overline{PF_1}$$ and $$\overline{PF_2}.$$ Take any other point $$Q$$ on $$w.$$ By the triangle inequality and the angle bisector theorem, $$2a = \left|LF_2\right| < {}$$$$\left|QF_2\right| + \left|QL\right| = {}$$$$\left|QF_2\right| + \left|QF_1\right|,$$ therefore $$Q$$ must be outside the ellipse. As this is true for every choice of $$Q,$$ $$w$$ only intersects the ellipse at the single point $$P$$ so must be the tangent line.
 * –jacobolus (t) 17:46, 3 August 2023 (UTC)

More on the focus-to-focus section
The new edit https://en.wikipedia.org/w/index.php?title=Ellipse&diff=next&oldid=1220981169 is practically incomprehensibly worded. I haven't undone it, because I don't want to discourage its author, who, sad to say, doesn't use a chosen user name. If the wording is not made clearly comprehensible soon, I will undo it. I would ask its editor to choose and use a Wikipedia user name. Generally, he should choose it to give himself privacy and security. It is just good manners to do so.Chjoaygame (talk) 23:55, 24 May 2024 (UTC)

 * It might be better to make a whole separate section about dynamical billiards in an ellipse. There are numerous sources about this topic, e.g. see google scholar. I'm not an expert though, and don't really feel motivated to write it. –jacobolus (t) 02:39, 25 May 2024 (UTC)
 * To save people the bother of clicking the diff, the text added was "Furthermore, due to the focus-to-focus reflection property of ellipses, if the reflected rays are allowed to continue propagating, they will eventually converge along a single direction along the major axis. Specifically, the rays will travel from one point on the major axis to another point on the opposite side of it." A diagram would be very helpful but I don't think incomprehensible is right. Johnuniq (talk) 03:35, 25 May 2024 (UTC)
 * It is not obvious that the focus-to-focus property causes convergence to the major axis! —Tamfang (talk) 19:22, 25 May 2024 (UTC)
 * Billiard paths passing outside the foci end up indefinitely bouncing around and around with their envelope as a confocal ellipse. In the limit as you move the path toward passing through one focus, this ellipse approaches the straight line segment between the foci. –jacobolus (t) 21:34, 25 May 2024 (UTC)

“c^2 = a^2 - b^2”?
In my humble opinion this article seems to omit an explanation for the key point that

$$c^2 = a^2 - b^2$$

Note the following is stated w/o a preface :

 * Linear eccentricity This is the distance from the center to a focus: $$c = \sqrt{a^2 - b^2}$$.

Also e.g., In the following figure the hypotenuse is labeled as “a” with no explanation:

[[File:Ellipse-param.svg|thumb|Shape parameters:a: semi-major axis,

b: semi-minor axis,

c: linear eccentricity,

p: semi-latus rectum (usually $\ell$).]]

(It would seem to me that a simple explanation could make use of the quoted assumption that “the ellipse is the set of points such that the sum of the distances PF1+PF2 is equal to 2a”, applied to the special case in the above figure in which the hypotenuse is clearly half of PF1+PF2.)

Apologies if I am missing something obvious! 😞 JdelaF (talk) 19:29, 11 June 2024 (UTC)

JdelaF (talk) 19:40, 11 June 2024 (UTC)

 * The relation $c^2 + b^2 = a^2$ is the Pythagorean relation between sides of a right triangle. There's some explanation of the meaning of a in . Feel free to add a couple more sentences someplace if you think the current explanations are too compressed. There's some trade off between concision vs. explicitness, but we don't want to leave readers behind. –jacobolus (t) 20:07, 11 June 2024 (UTC)

title: Talk:Ellipse


text:
Internet Storm Center

The Internet Storm Center (ISC) is a program of the SANS Technology Institute, a branch of the SANS Institute which monitors the level of malicious activity on the Internet, particularly with regard to large-scale infrastructure events.

History
The ISC evolved from "Incidents.org", a site initially founded by the SANS Institute to assist in the public-private sector cooperation during the Y2K cutover. In 2000, Incidents.org started to cooperate with DShield to create a Consensus Incidents Database (CID). It collected security information from cooperating sites and agencies for mass analysis.

On March 22, 2001, the SANS CID was responsible for the early detection of the "Lion" worm attacks on various facilities. The quick warning and counter-efforts organized by the CID were instrumental in controlling the damage done by this worm, which otherwise might have been considerably worse.

Later, DShield was integrated closer into incidents.org as the SANS Institute started to sponsor DShield. The CID was renamed the "Internet Storm Center" in acknowledgement of the way it uses the distributed sensor network similar to the way a weather reporting center will detect and track an atmospheric storm and provide warnings. Since that time the ISC has expanded its monitoring operations; its website cites a figure of over twenty million "intrusion detection log entries" per day. It continues to provide analyses and alerts of security threats to the Internet community.

During the last hours of 2005 and the first weeks of 2006, the Internet Storm Center went to its longest period at the time to "yellow" on the Infocon for the WMF vulnerability.

The most prominent feature of the ISC is a daily "Handler Diary" which is prepared by one of the 40 volunteer incident handlers and summarized the events of the day. It frequently is the first public source for new attack trends and actively facilitates cooperation by soliciting more information to understand particular attacks better.

The Internet Storm Center is currently staffed with approximately 40 volunteers, representing 8 countries and many industries.

Notable members

 * Director of the ISC: Marcus Sachs
 * Chief Technical Officer: Johannes Ullrich
 * Handler Tom Liston

title: Internet Storm Center


text:
Blue box

A blue box is an electronic device that produces tones used to generate the in-band signaling tones formerly used within the North American long-distance telephone network to send line status and called number information over voice circuits. During that period, charges associated with long-distance calling were commonplace and could be significant, depending on the time, duration and destination of the call. A blue box device allowed for circumventing these charges by enabling an illicit user, referred to as a "phreaker" to place long-distance calls, without using the network's user facilities, that would be billed to another number or dismissed entirely by the telecom company's billing system as an incomplete call. A number of similar "color boxes" were also created to control other aspects of the phone network.

First developed in the 1960s and used by a small phreaker community, the introduction of low-cost microelectronics in the early 1970s greatly simplified these devices to the point where they could be constructed by anyone reasonably competent with a soldering iron or breadboard construction. Soon after, models of relatively low quality were being offered fully assembled, but these often required tinkering by the user to remain operational.

Over time, as the long-distance network became digitized, the audio call-control tones were replaced with out-of-band signaling methods in the form of common-channel signaling (CCS) carried digitally on a separate channel inaccessible to the telephone user. This development limited the usefulness of audio-tone-based blue boxes by the 1980s, and they are of little to no use today.

Automated dialing
Local calling had been increasingly automated through the first half of the 20th century, but long-distance calling still required operator intervention. Automation was deemed essential by AT&T. By the 1940s they had developed a system that used audible tones played over the long-distance lines to control network connections. Tone pairs, referred to as multi-frequency (MF) signals, were assigned to the digits used for telephone numbers. A different, single tone, referred to as single frequency (SF), was used as a line status signal.

This new system allowed the telephone network to be increasingly automated by deploying the dialers and tone generators on an as-required basis, starting with the busier exchanges. Bell Labs was happy to advertise their success in creating this system, and repeatedly revealed details of its inner workings. In the February 1950 issue of Popular Electronics, they published an advertisement, Playing a Tune for a Telephone Number, which showed the musical notes for the digits on a staff and described the telephone operator's pushbuttons as a "musical keyboard". Two keys on a piano would need to be pushed simultaneously to play the tones for each digit. The illustration did not include the tone pairs for the special control signals KP and ST, although in the picture the operator's finger is on the KP key and the ST key is visible. In the 1950s, AT&T released a public relations film, "Speeding Speech", which described the operation of the system. In the film, the tone sequence for sending a complete telephone number is heard through a loudspeaker as a technician presses the keys for dialing.

In November 1954, the Bell System Technical Journal published an article entitled "In-Band Single-Frequency Signaling", which described the signaling scheme used for starting and ending telephone calls for the purpose of routing over trunk lines. In November 1960, an article in the Bell System Technical Journal provided an overview of the technical details of signaling systems, and disclosed the frequencies of the signals.

The system was relatively complex for 1950s technology. It had to accurately decode the frequencies and ignore any signals where that frequency might be accidentally created; music playing in the background might randomly contain the SF tones and the system had to filter these out. To do this, the signaling unit compared the signal power from a bandpass filter centered on 2600 Hz to signal power in other parts of the audio band, and only triggered if the tone was the most prominent signal. The originating end of the call would play the tone into the trunk line when the call ended, and trigger the remote end to end the call. After a short time, the originating end reduced the tone level and continued to send tone as long as it received on hook status from its local equipment.

Discovery and early use
Before the technical details were published, many users discovered unintentionally, and to their annoyance, that a 2600 Hz tone played into the caller's handset would cause a long-distance call to disconnect. The 2600 Hz tone might be present if the caller were whistling into the telephone microphone while waiting for the called party to answer. Upon detecting the tone from the caller's end, the receiving signaling unit sent an on hook status to the connected equipment, which disconnected the call from that point forward, as if the caller had hung up.

Among the earliest to discover this effect was Joe Engressia, known as Joybubbles, who accidentally discovered it at the age of seven by whistling. He became fascinated with the phone network, and over the next decade had built up a considerable base of knowledge about the system and how to place calls using the control tones. He and other phone phreaks, such as "Bill from New York" and "The Glitch", trained themselves to whistle 2600 Hz to reset a trunk line. They also learned how to route telephone calls by flashing, that is using very short pulses of the on-hook signal, to send routing instructions.

At one point in the 1960s, packages of the Cap'n Crunch breakfast cereal included a free gift: a small whistle that, by coincidence, generated a 2600 Hz tone when one of the whistle's two holes was covered. The phreaker John Draper adopted his nickname "Captain Crunch" from this whistle.

The "toll free" 800 service was launched in 1967 and gave the hackers easy numbers to call. The user would generally choose a number in the target area and then use it as above. Even if billing information were generated, it would be to a 1-800 number and thus free of charge. As before, the remote system would notice a call going to the ultimate non-free number, but could not match the other end.

Technology
It was technically possible to generate the tones with the technology available at the time the system was first deployed. A piano or electronic organ had keys that were close enough in frequency to work. With tuning, they could even be made dead on frequency. For dialing the phone number, the user would press 2 keys at a time. An experienced pianist might have found the key combinations awkward to play. But a blank player piano roll could have been punched to operate the required keys and dial a phone number. Another strategy would have been to purchase doorbells, remove the plungers, and mount them on a frame that could be set over the piano keyboard. Twelve DPDT pushbuttons, labelled KP, ST and the 10 digits, would operate pairs of plungers to play the phone company tones, after the E7 piano key had been pressed and released.

At the time, there were consumer devices for recording on wire or blank phonograph records, so the piano did not have to be near the phone. Consumer tape recorders came later and made the recording process easier. Small, battery powered, tape recorders allowed the tones to be played back almost anywhere.

It was possible to construct an electronic blue box with 1940s vacuum tube technology, but the device would have been relatively large and power hungry. Just as it did for radios, shrinking them from the size of toasters to the size of cigarette packages and allowing them to be powered by small batteries, transistor technology made a small, battery powered, electronic blue box practical.

AT&T security captured its first blue box in about 1962, but it probably was not the first one built.

A typical blue box had 13 pushbuttons. One button would be for the 2600 Hz tone, pressed and released to disconnect the outgoing connection and then connect a digit receiver. There would be a KP button, to be pressed next, 10 buttons for telephone number digits, and the ST button to be pressed last. The blue box may have had 7 oscillators, 6 for the 2 out of 6 digit code and one for the 2600 Hz tone, or 2 oscillators with switchable frequencies.

The blue box was thought to be a sophisticated electronic device and sold on the black market for a typical $800–1,000 or as much as $3,500. Actually, designing and building one was within the capabilities of many electronics students and engineers with knowledge of the required tones, using published designs for electronic oscillators, amplifiers and switch matrixes, and assembled with readily available parts. Furthermore, it was possible to generate the required tones using consumer products or lab test equipment. The tones could be recorded on small, battery powered, cassette recorders for playback anywhere. In the early 1980s, Radio Shack sold pairs of Intersil 8038 voltage-controlled oscillator chips which were ideal for the purpose. A common hack was to use a TI-30 pocket calculator as the chassis of the device, with the diodes for the switch matrix wired into the keypad. An miniature audio jack connected through the recharge port for the calculator's optional rechargeable battery would then be used to connect the speaker to play the tones into the handset.

To reduce call set up time, telephone numbers were transmitted from machine to machine in a "speed dial" format, about 1.5 seconds for a 10 digit number, including KP and ST. To catch the cheaters, AT&T could have connected monitors to digit receivers that were not being used for operator dialed calls and logged calls dialed at manual speed. So, some hackers went to the extra trouble of building blue boxes that stored telephone numbers and played the tones with the same timing as the machines.

Subculture
The widespread ability to blue box, once limited to just a few isolated individuals exploring the telephone network, developed into a subculture. Famous phone phreaks such as "Captain Crunch", Mark Bernay, and Al Bernay used blue boxes to explore the various "hidden codes" that could not be dialled by a standard telephone.

Some of the more famous pranksters were Steve Wozniak and Steve Jobs, founders of Apple Computer. On one occasion, Wozniak dialed Vatican City and identified himself as Henry Kissinger (imitating Kissinger's German accent) and asked to speak to the Pope (who was sleeping at the time). Wozniak said in 1986:

"I called only to explore the phone company as a system, to learn the codes and tricks. I'd talk to the London operator, and convince her I was a New York operator. When I called my parents and my friends, I paid. After six months I quit—I'd done everything that I could.

I was so pure. Now I realize others were not as pure, they were just trying to make money. But then I thought we were all pure."

Jobs later told his biographer that if it had not been for Wozniak's blue boxes, "there wouldn't have been an Apple."

In the media
Blue boxing hit the mainstream media when an article by Ron Rosenbaum titled Secrets of the Little Blue Box was published in the October 1971 issue of Esquire magazine. Suddenly, many more people wanted to get into the phone phreaking culture spawned by the blue box, and it furthered the fame of Captain Crunch.

In June 1972, Ramparts magazine printed the wiring schematics necessary to create a mute box (a variant of the blue box). All sold issues were recalled or seized from newsstands by police and officials of Pacific Bell, causing financial loss to the magazine. The magazine ceased operations for good in 1975.

The amateur radio magazine '73' published an article on the telephone system in the mid-1970s. The June 1975 issue of 73 magazine carried an article describing the rudiments of the long-distance signaling network, and how to construct and operate red and blue boxes. This article included a blue box schematic using the Intersil 8038 voltage controlled oscillator chip. Around the same time, do-it-yourself blue box kits became available.

In November 1988, the CCITT (now known as ITU-T) published recommendation Q.140 for the Signaling System No. 5, which caused a resurgence of blue boxing by a new generation of users.

In the early 1990s, blue boxing became popular with the international warez scene, especially in Europe. Software was made to enable blue boxing using a computer to generate and play the signaling tones. For the PC there were BlueBEEP, TLO, and others, and blue boxes were available for other platforms such as Amiga.

Automating dialing
Local plain old telephone service works by watching the voltage on the telephone lines between the telephone company's exchange office and the customer's telephone. When the phone is on-hook ("hung up") the approximately 48 volt electricity from the exchange flows to the phone and is looped back without passing through the handset. When the user picks up the handset, the current has to flow through the speaker and microphone in it, causing the voltage to drop to under 10 V. This sudden drop in voltage signals the user has picked up the phone.

Originally, all calls were routed manually by an operator who would look for small light bulbs that would illuminate when a subscriber picked up the phone to make a call. The operator would connect a handset to the line, ask the user who they were calling, and then connect a cable between two phone jacks to complete the call. If the user was placing a long-distance call, the local operator would first talk to an operator at the remote exchange using one of the trunk lines between the two locations. When the local operator heard the remote customer come on the line, they would connect their local customer to the same trunk line to complete the call.

The calling process began to be automated from the earliest days of the telephone system. Increasingly sophisticated electromechanical systems would use the changes in voltage to start the connection process. The rotary dial was introduced around 1904 to operate these switches; the dial repeatedly rapidly connects and disconnects the line, a process known as pulse dialing. In common systems, these periodic changes in voltage caused a stepper motor to rotate one position for each pulse of a digit, with longer pauses to switch from one rotary switch to another. When enough digits had been decoded, typically seven in North America, connections between the rotors would select a single line, the customer being dialed.

The idea of using changing voltages to complete the call worked well for the local exchange where the distance between the customer and exchange office might be on the order of a few kilometers. Over longer distances, the capacitance of the lines filter out any rapid changes in voltage and dialing pulses do not reach the remote office in clean form, so that long-distance calls still required operator intervention. As telephone use grew, long-distance calling in particular, telephone companies were increasingly interested in automating this type of connection.

Long-distance direct dialing
To address this need, the Bell System adopted a second system on the circuits that connected the exchanges. When the user dialed a long-distance number, indicated in North America by dialing a "1" at the beginning of the number, the call was switched to a separate system known as a "tandem". The tandem would then buffer the remaining digits and decode the number to see which remote exchange was being dialed, generally using the area code for this purpose. They would then look for a free trunk line between the two exchanges; if none were available the tandem would play the "fast busy" reorder signal to tell the user to try again later.

The basic protocol for finding a free line worked by playing a 2600 Hz tone into the line whenever it was not being used. The tandems at both ends of a given trunk line did this. When the tandem determined which remote exchange was being called it scanned the trunk lines between the two exchanges looking for the tone. When it heard the tone on one of the lines, it knew that line was free to use. They would then select that line and drop the 2600 Hz tone from their end. The remote tandem would hear the tone stop, drop their tone, and then play a supervision flash, making a "ka-cheep" sound, to indicate they had noticed the signal. The line was now free on both ends to connect a call.

Pulse dialing still had the problem that sending the dialed number to the remote exchange would not work due to the capacitance of the network. The tandems solved this by buffering the phone number and then converting each digit into a series of two tones, the multi-frequency signaling system, or "MF". Once the local tandem had found a free line and connected to it, it then relayed the rest of the phone number over the line using the tone dialing method. The remote tandem then decoded the tones and turned them back into pulses on the local exchange. To indicate the start and end of a series of MF digits, special MF tones, KP and ST, were used.

When the call was finished and one of the parties hung up the phone, their exchange would notice the change in voltage and begin playing the 2600 Hz tone into the trunk line. The other end of the connection would respond to the tone by causing their local call to hang up as well, and then began playing the tone into their end as before, to mark the line as free at both ends.

Blue boxing
The blue box consisted of several of audio oscillators, a telephone keypad, an audio amplifier and a speaker. To operate a blue box, the user placed a long-distance telephone call, often to a number that was in the target area. Usually, this initial call would be to a 1-800 number or some other non-supervising telephone number such as directory assistance. Using a toll-free number ensured that the phone being used for access would not be billed.

When the call began to ring, the caller would hold the blue box speaker over the microphone in the handset and use the box to send the 2600 Hz tone (or 2600+2400 Hz on many international trunks followed by a 2400 Hz tone). The called office interprets this tone as the caller hanging up before the call completed, disconnects the call, and begins playing 2600 Hz to mark the line free. However, this does not disconnect the call at the caller's end, only physically hanging up the phone will do that. This leaves the caller on a live line that is connected via a long-distance trunk line to a target exchange.

The caller now stops playing the tone. The called exchange interprets this loss of tone to mean the exchange's tandem is attempting to place another call. It responds by dropping its tone and then playing the flash to indicate it is ready to accept routing tones. Once the called end sends the supervision flash, the caller uses the blue box to send a "Key Pulse" or "KP", the tone that starts a routing digit sequence, followed by either a telephone number or one of the numerous special codes that were used internally by the telephone company, then finished with a "Start" tone, "ST". At this point, the called end of the connection would route the call the way it was told, while the caller's local exchange would act as if the call was still ringing at the original number.

Countermeasures
Blue boxing remained rare until the early 1970s when the required systems began to drop in cost and the concept began to be more widely known. At the time, phreakers felt there was nothing Bell Telephone could do to stop blue boxing because it would require Bell to upgrade all their hardware.

For the immediate term, Bell responded with a number of blue box detection and law enforcement countermeasures. Armed with records of all long-distance calls made, kept by both mechanical switching systems and newer electronic switching systems, including calls to toll-free telephone numbers which did not appear on customer bills, telephone security employees began examining those records looking for suspicious patterns of activity. For instance, at the time, calls to long-distance information, while answered, deliberately did not return the electrical "off hook" signal indicating that they had been answered. When an information call was diverted to another number that answered, the billing equipment would log that event. Billing computers processed the logs and generated lists of calls to information that had been answered with an off-hook tone. In the early days, the lists were probably intended to detect equipment malfunctions, but the follow-up investigation did lead to blue box users. After the toll free "800" service was inaugurated, the billing computers were also programmed to generate lists of lengthy calls to toll free numbers. While many of these calls were legitimate, telephone security employees would examine the lists and follow up irregularities.

In this case, filters could be installed on those lines to block the blue box. Bell also would wiretap the affected lines. In one 1975 case, the Pacific Telephone Company targeted one defendant's line with the following equipment:
 * A CMC 2600, a device which registers on a counter the number of times a 2600 Hz tone is detected on the line;
 * A tape recorder, activated automatically by the CMC 2600 to record two minutes of telephone audio after each burst of 2600 Hz activity; and
 * A Hekemian 51A, which replicates the functions of the CMC 2600 and also produces a paper tape print-out of outgoing calls. Ordinary calls were recorded in black ink and destination numbers called via the blue box were recorded in red ink.

These actions resulted in several highly publicized trials.

Decline
The ultimate solution to the blue box vulnerability was to do what the phreakers thought impossible and upgrade the entire network. This process occurred in stages, some of which were already well underway in the early 1970s.

The T1 system was developed beginning in 1957 and began to be deployed around 1962. It digitized the voice signals so that they could be more efficiently carried in high-density connections between exchanges, carrying 24 lines on a single 4-wire connection. Depending on the network layout, the user might no longer be connected directly to a tandem, but instead to a local office that forwarded the signal over a T1 to a more distant exchange that did have the tandem. Simply due to the way the system worked, the supervisory signals had to be filtered out in order for the digitization of the analog signal to work. Recall that the 2600 Hz tone was not dropped from the trunk until the line was connected all the way and would be mixed with other tones like the ringing or busy signal; when used over a T1 this tone mixed with other signals and caused a problem known as "quantization noise" that distorted the sound. These tones were thus filtered down on either side of the T1 connection. Thus it was difficult to blue box in such an environment, although successes are known.

But blue boxing was eventually eliminated entirely for unrelated reasons. In the existing tandem-based network, completing a call required several stages communicating over the trunk line, even if the remote user never answered the call. As this process might take on the order of 10 to 15 seconds, the total wasted time across all of the trunk lines could be used to carry additional calls. To improve line usage, Bell began the development of the Number One Electronic Switching System (1ESS). This system performed all the calling and line supervision using a separate private line between the two offices. Using this system, when a long-distance call was placed the trunk line was not initially used. Instead, the local office sent a message containing the called number to the remote exchange using this separate channel. The remote office would then attempt to complete the call, and indicate this to the original office using the same private line. Only if the remote user answered would the systems attempt to find a free trunk line and connect, thereby reducing the use of the trunk lines to the absolute minimum.

This change also meant the signaling system was available internally to the network on this separate line. There was no connection between the user lines and this signaling line, so there was no route by which the users could influence the dialing. The same rapid reduction in prices that made the blue box possible also led to the rapid reduction in cost of the ESS systems. First applied only to their busiest connections, by the 1980s, the latest 4ESS models and similar machines from other companies were deployed to almost all major exchanges, leaving only corners of the network still connected using tandems. Blue boxing worked if one connected to such an exchange, but could only be used end-to-end if the entire network between the two endpoints consisted only of tandems, which became increasingly rare and disappeared by the late 1980s.

Analog long-distance transmission systems remained more cost effective for the long haul circuits until, at least, the 1970s. Even then, there was a huge installed base of analog circuits, and it made better economic sense to keep using them. It was not until competitor Sprint built its all digital, "quiet", network, where "you could actually hear a pin drop", that AT&T took a multi-billion dollar write-off and upgraded its long-distance network to digital technology.

The phreaking community that had emerged during the blue box era evolved into other endeavors and there currently exists a commercially published hacking magazine, titled 2600, a reference to the 2600 Hz tone that was once central to so much of telephone hacking.

Frequencies and timings
Each multifrequency tone consists of two frequencies chosen from a set of six, shown in the table on the left. The Touch Tone encoding is shown by the table on the right:

The rightmost column is not present on consumer telephones.

Normally, the tone durations for passing numbers from machine to machine in a "speed dialing" format are on for 60 ms, with 60 ms of silence between digits. The 'KP' and 'KP2' tones are sent for 100 ms. KP2 (ST2 in the R1 standard) was used for dialing internal Bell System telephone numbers. However, actual tone durations can vary slightly depending on location, switch type, and the machine status.

For operators, technicians, and blue box phone phreakers, the tone durations would be set by how long the buttons were held down and, for silence, how long before manually pressing the next button.

A blue box could have been constructed which would send the tones with machine to machine timing, with the number either stored in digital memory or a matrix of switches. In the switch matrix, there might be 10 rows for digits, each with 5 switches. Two switches would be moved to on, selecting the 2 tones. (KP and ST would be hard wired.) The 5 switches could be labelled 0, 1, 2, 4, and 7, with the user selecting pairs of switches adding to each digit, with special case 4 plus 7 for digit 0.

Alternatively, the tones could be recorded on magnetic tape, which would be cut into pieces and spliced together, using a commercial splicer for accurate alignment. If the phreaker matched machine dialing and recorded at 7.5 ips (inches per second), the splices for tone and silence would be about 1/2-inch long., with KP 3/4-inch long. For more manageable splicing lengths, the phreaker could use a 15 ips tape recorder, which was less common, and double those lengths. For those without a 15 ips machine but having 2 tape recorders, the tones could be recorded an octave low at 7.5 ips, the pieces spliced together would be were double those lengths. The spliced tape would be re-recorded from a 7.5 ips machine to a 3.75 ips machine. The resulting recording could be played back at 7.5 ips. An interval of 2600 Hz, to disconnect the trunk, followed by an interval of silence, to give enough time for a digit receiver to connect, would be added to precede KP.

This set of MF tones was originally devised for Bell System long-distance operators placing calls manually, as well as machine to machine dialing, and predates the DTMF Touch-Tone system used by subscribers. The leading 1 for customer dialed long-distance calls was not dialed. For operators, the line was muted during dialing, but, for customer telephones, it was only muted while a key was pressed. The Touch Tone frequencies were chosen to minimize the risk of customer talking while dialing, or background sounds, being registered as a digit or digits and resulting in a wrong number. Muting guarded against that happening during operator dialing, so the MF system did not have to be, and was not, so robust. The tones have a simple 200 Hz spacing. For Touch Tone, harmonic relationships and intermodulation products were taken into account in the choice of tones.

Special codes
Some of the special codes a person could get onto are in the chart below. "NPA" is a telephone company term for 'area code'.

Many of these appear to have been originally three-digit codes, dialed without the leading area code, and the format of destination numbers dialed to the international senders has changed at various points as the ability to call additional nations was added.
 * NPA+100 – Plant Test – Balance termination
 * NPA+101 – Plant Test – Toll Testing Board
 * NPA+102 – Plant Test – Milliwatt tone (1004 Hz)
 * NPA+103 – Plant Test – Signaling test termination
 * NPA+104 – Plant Test – 2-way transmission and noise test
 * NPA+105 – Plant Test – Automatic Transmission Measuring System
 * NPA+106 – Plant Test – CCSA loop transmission test
 * NPA+107 – Plant Test – Par meter generator
 * NPA+108 – Plant Test – CCSA loop echo support maintenance
 * NPA+109 – Plant Test – Echo canceler test line
 * NPA+121 – Inward Operator
 * NPA+131 – Operator Directory assistance
 * NPA+141 – Rate and Route Information
 * 914+151 – Overseas incoming (White Plains, NY)
 * 212+151 – Overseas incoming (New York, NY)
 * NPA+161 – trouble reporting operator (defunct)
 * NPA+181 – Coin Refund Operator
 * 914+182 – International Sender (White Plains, NY)
 * 212+183 – International Sender (New York, NY)
 * 412+184 – International Sender (Pittsburgh, PA)
 * 407+185 – International Sender (Orlando, FL)
 * 415+186 – International Sender (Oakland, CA – in this era, 510 was TWX)
 * 303+187 – International Sender (Denver, CO)
 * 212+188 – International Sender (New York, NY)

Not all NPAs had all functions. As some NPAs contained multiple cities, an additional routing code was sometimes placed after the area code. For instance, 519+044+121 may reach the Windsor inward operator and 519+034+121 the London inward operator 175 km distant, but in the same area code.

In other countries
Another signaling system widely used on international circuits (except those terminating in North America) was CCITT Signaling System No. 4 (friendly named 'SS4').

Technical definitions are specified in formerly CCITT (now ITU-T) Recommendations Q.120 to Q.139.

This was also an in-band system but, instead of using multifrequency signals for digits, it used four 35 ms pulses of tone, separated by 35 ms of silence, to represent digits in four-bit binary code, with 2400 Hz as a '0' and 2040 Hz as a '1'. The supervisory signals used the same two frequencies, but each supervisory signal started with both tones together (for 150 ms) followed, without a gap, by a long (350 ms) or short (100 ms) period of a single tone of 2400 Hz or 2040 Hz. Phreaks in Europe built System 4 blue boxes that generated these signals. Because System 4 was used only on international circuits, the use of these blue boxes was more specialized.

Typically, a phreak would gain access to international dialing at low or zero cost by some other means, make a dialed call to a country that was available via direct dialing, and then use the System 4 blue box to clear down the international connection and make a call to a destination that was available only via operator service. Thus, the System 4 blue box was used primarily as a way of setting up calls to hard-to-reach operator-only destinations.

A typical System 4 blue box had a keypad (for sending four-bit digit signals) plus four buttons for the four supervisory signals (clear-forward, seize-terminal, seize-transit, and transfer-to-operator). After some experimentation, nimble-fingered phreaks found that all they needed was two buttons, one for each frequency. With practice, it was possible to manually generate all the signals with sufficient timing precision, including the digit signals. This made it possible to make the blue box quite small.

A refinement added to some System 4 blue boxes was an anti-acknowledgment-echo guard tone. Because the connection between the telephone and the telephone network is two-wire, but the signaling on the international circuit operates on a four-wire basis (totally separate send and receive paths), signal-acknowledgment tones (single pulses of one of the two frequencies from the far end of the circuit after receipt of each digit) tended to be reflected at the four-wire/two-wire conversion point. Although these reflected signals were relatively faint, they were sometimes loud enough for the digit-receiving circuits at the far end to treat them as the first bit of the next digit, messing up the phreak's transmitted digits.

What the improved blue box did was to continuously transmit a tone of some other frequency (e.g., 600 Hz) as a guard tone whenever it was not sending a System 4 signal. This guard tone drowned out the echoed acknowledgment signals so that only the blue box-transmitted digits were heard by the digit-receiving circuits at the far end.

title: Blue box