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Screened Poisson equation

In physics, the screened Poisson equation is a Poisson equation, which arises in (for example) the Klein–Gordon equation, electric field screening in plasmas, and nonlocal granular fluidity in granular flow.

Statement of the equation
The equation is $$ \left[ \Delta - \lambda^2 \right] u(\mathbf{r}) = - f(\mathbf{r}), $$

where $$\Delta$$ is the Laplace operator, λ is a constant that expresses the "screening", f is an arbitrary function of position (known as the "source function") and u is the function to be determined.

In the homogeneous case (f=0), the screened Poisson equation is the same as the time-independent Klein–Gordon equation. In the inhomogeneous case, the screened Poisson equation is very similar to the inhomogeneous Helmholtz equation, the only difference being the sign within the brackets.

Electrostatics
In electric-field screening, screened Poisson equation for the electric potential $$\phi(\mathbf r)$$ is usually written as (SI units)

$$ \left[ \Delta - k_0^2 \right] \phi(\mathbf{r}) = - \frac{\rho_{\rm ext}(\mathbf{r})}{\epsilon_0}, $$

where $$k_0^{-1}$$ is the screening length, $$\rho_{\rm ext}(\mathbf r)$$ is the charge density produced by an external field in the absence of screening and $$\epsilon_0$$ is the vacuum permittivity.This equation can be derived in several screening models like Thomas–Fermi screening in solid-state physics and Debye screening in plasmas.

Three dimensions
Without loss of generality, we will take λ to be non-negative. When λ is zero, the equation reduces to Poisson's equation. Therefore, when λ is very small, the solution approaches that of the unscreened Poisson equation, which, in dimension $$n=3$$, is a superposition of 1/r functions weighted by the source function f:

$$ u(\mathbf{r})_{(\text{Poisson})} = \iiint \mathrm{d}^3r' \frac{f(\mathbf{r}')}{4\pi |\mathbf{r} - \mathbf{r}'|}. $$

On the other hand, when λ is extremely large, u approaches the value f/λ2, which goes to zero as λ goes to infinity. As we shall see, the solution for intermediate values of λ behaves as a superposition of screened (or damped) 1/r functions, with λ behaving as the strength of the screening.

The screened Poisson equation can be solved for general f using the method of Green's functions. The Green's function G is defined by

$$ \left[ \Delta - \lambda^2 \right] G(\mathbf{r}) = - \delta^3(\mathbf{r}), $$ where δ3 is a delta function with unit mass concentrated at the origin of R3.

Assuming u and its derivatives vanish at large r, we may perform a continuous Fourier transform in spatial coordinates:

$$ G(\mathbf{k}) = \iiint \mathrm{d}^3r \; G(\mathbf{r}) e^{-i \mathbf{k} \cdot \mathbf{r}} $$

where the integral is taken over all space. It is then straightforward to show that

$$ \left[ k^2 + \lambda^2 \right] G(\mathbf{k}) = 1. $$

The Green's function in r is therefore given by the inverse Fourier transform,

$$ G(\mathbf{r}) = \frac{1}{(2\pi)^3} \; \iiint \mathrm{d}^3\!k \; \frac{e^{i \mathbf{k} \cdot \mathbf{r}}}{k^2 + \lambda^2}. $$

This integral may be evaluated using spherical coordinates in k-space. The integration over the angular coordinates is straightforward, and the integral reduces to one over the radial wavenumber $$ k_r $$:

$$ G(\mathbf{r}) = \frac{1}{2\pi^2 r} \; \int_0^\infty \mathrm{d}k_r \; \frac{k_r \, \sin k_r r }{k_r^2 + \lambda^2}. $$

This may be evaluated using contour integration. The result is:

$$ G(\mathbf{r}) = \frac{e^{- \lambda r}}{4\pi r}. $$

The solution to the full problem is then given by

$$ u(\mathbf{r}) = \int \mathrm{d}^3r' G(\mathbf{r} - \mathbf{r}') f(\mathbf{r}') = \int \mathrm{d}^3r' \frac{e^{- \lambda |\mathbf{r} - \mathbf{r}'|}}{4\pi |\mathbf{r} - \mathbf{r}'|} f(\mathbf{r}'). $$

As stated above, this is a superposition of screened 1/r functions, weighted by the source function f and with λ acting as the strength of the screening. The screened 1/r function is often encountered in physics as a screened Coulomb potential, also called a "Yukawa potential".

Two dimensions
In two dimensions: In the case of a magnetized plasma, the screened Poisson equation is quasi-2D: $$ \left( \Delta_\perp - \frac{1}{\rho^2} \right)u(\mathbf{r}_\perp) = -f(\mathbf{r}_\perp) $$ with $$\Delta_\perp=\nabla\cdot\nabla_\perp$$ and $$\nabla_\perp=\nabla-\frac{\mathbf{B}}{B}\cdot \nabla$$, with $$\mathbf{B}$$ the magnetic field and $$\rho$$ is the (ion) Larmor radius. The two-dimensional Fourier Transform of the associated Green's function is: $$ G(\mathbf{k_\perp}) = \iint d^2 r~G(\mathbf{r}_\perp) e^{-i\mathbf{k}_\perp\cdot\mathbf{r}_\perp}. $$ The 2D screened Poisson equation yields: $$ \left( k_\perp^2 +\frac{1}{\rho^2} \right) G(\mathbf{k}_\perp) = 1. $$ The Green's function is therefore given by the inverse Fourier transform: $$ G(\mathbf{r}_\perp) = \frac{1}{4\pi^2} \; \iint \mathrm{d}^2\!k \; \frac{e^{i \mathbf{k}_\perp \cdot \mathbf{r}_\perp}}{k_\perp^2 + 1 / \rho^2}. $$ This integral can be calculated using polar coordinates in k-space: $$ \mathbf{k}_\perp = (k_r\cos(\theta), k_r\sin(\theta)) $$ The integration over the angular coordinate gives a Bessel function, and the integral reduces to one over the radial wavenumber $$ k_r $$: $$ G(\mathbf{r}_\perp) = \frac{1}{2\pi} \; \int_0^\infty \mathrm{d}k_r \; \frac{k_r \, J_0(k_r r_\perp)}{k_r^2 + 1 / \rho^2} = \frac{1}{2\pi} K_0(r_\perp \, / \, \rho). $$

Connection to the Laplace distribution
The Green's functions in both 2D and 3D are identical to the probability density function of the multivariate Laplace distribution for two and three dimensions respectively.

title: Screened Poisson equation


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Resignation from the House of Commons of the United Kingdom

As a constitutional convention, members of Parliament (MPs) sitting in the House of Commons of the United Kingdom are not formally permitted to resign their seats. To circumvent this prohibition, MPs who wish to step down are instead appointed to an "office of profit under the Crown"; by law, such an appointment disqualifies them from sitting in Parliament. For this purpose, a legal fiction has been maintained where two unpaid sinecures are considered to be offices of profit: Steward and Bailiff of the Chiltern Hundreds, and Steward and Bailiff of the Manor of Northstead.

Since the passage of the House of Commons Disqualification Act 1975, general "offices for profit" are no longer disqualifying, but the explicit list of hundreds of disqualifying offices contained in the act now includes the two stewardships so this convention can be continued. It is rare for an MP to be nominated to an legitimate office of profit on the disqualifying list; no MPs have lost their seat by being appointed to an actual office since 1981, when Thomas Williams became a judge.

Offices used for disqualification
Members of Parliament (MPs) wishing to give up their seats before the next general election are appointed to an office which causes the MP to be disqualified from membership. Historically, all "offices of profit under the Crown" could be used for this purpose. However, only two are still in use:

 * Crown Steward and Bailiff of the three Chiltern Hundreds of Stoke, Desborough and Burnham
 * Crown Steward and Bailiff of the Manor of Northstead

The stewardships are unpaid positions that provide no benefits and carry no responsibilities. The Chiltern Hundreds last required an actual Steward in the 16th century. The main property of the Manor of Northstead was described in 1600 as "unfit for habitation" after "it fell down". The stewardships have been maintained as nominal offices of profit solely as a legal fiction to meet the requirements of the House of Commons Disqualification Act 1975 and its predecessors.

The offices are used alternately, making it possible for two members to resign at the same time. When more than two MPs resign at a time—for example, when 15 Ulster Unionist MPs resigned in protest at the Anglo-Irish Agreement on 17 December 1985—the resignations are, in theory, not simultaneous but spread throughout the day, enabling each member to hold one of the offices for a short time. The former office-holder may subsequently be reelected to Parliament.

Origins
Resignation from the House of Commons has never been allowed in theory, although five MPs were allowed to resign in the early 17th century on grounds of ill health. On 2 March 1624 N.S., Parliament formalized the prohibition by passing a resolution "... that a man, after he is duly chosen, cannot relinquish." At the time, serving in Parliament was considered an obligation to be borne rather than a position of power and honour. Members had to travel to Westminster over a primitive road system, a real problem for those who represented more distant constituencies. An MP could not effectively tend to personal business at home while he was away at Parliament, yet MPs were unpaid until 1911.

Originally, the disqualification of office holders from Parliament came about as part of the long struggle to ensure that Parliament would remain free from undue influence on the part of the monarch. Since anyone receiving a salary from the Crown could not be truly independent, the House of Commons passed a resolution on 30 December 1680 stating that an MP who "shall accept any Office, or Place of Profit, from the Crown, without the Leave of this House ... shall be expelled [from] this House." The prohibition was strengthened over the following decades to bar MPs from simultaneously holding certain offices. However, MPs were able to hold crown stewardships until 1740, when Sir Watkin Williams-Wynn became Steward of the Lordship and Manor of Bromfield and Yale and was deemed to have vacated his Commons seat. The Irish House of Commons largely followed the procedure of the English Commons; however, whereas in England the prohibition on MPs holding offices under the crown continued to rest on resolutions, the Parliament of Ireland passed an act in 1793 to enforce it.

Development of procedure
After the precedent set in 1740, it became possible for MPs to step down by being appointed to a crown stewardship. The procedure was invented by John Pitt, who wanted to vacate his seat for Wareham in order to stand for Dorchester, as he could not be a candidate while he was still an MP. Moreover, it quickly became apparent that if ministers of the Crown were to be meaningfully responsible to Parliament, they needed to be able to sit in the House of Commons. For this reason, someone appointed to an office of profit was only disqualified from continuing to sit in the House of Commons; it was possible for someone already in office to be (re-)elected to Parliament without relinquishing the office.

Pitt wrote to Prime Minister Henry Pelham in May 1750, reporting he had been invited to stand in Dorchester, and asking for "a new mark of his Majesty's favour [to] enable me to do him these further services". Pelham wrote to William Pitt (the elder) indicating that he would intervene with King George II to help. On 17 January 1751, Pitt was appointed to the office of Steward of the Chiltern Hundreds, and was then elected unopposed for Dorchester. The Manor of Northstead was first used for resignation on 6 April 1842 by Patrick Chalmers, Member for the Montrose District of Burghs.

The Chancellor may in theory deny an application, although the last time this happened was to Viscount Chelsea in 1842. In the debate over expelling the fugitive James Sadleir in 1856, the Government committed to refusing any potential application he would make. After Edwin James was appointed to the Chiltern Hundreds upon fleeing to the United States with a £10,000 debt in the 1860s, the letter of appointment was revised to omit the customary mention of the position as one of honour. When Charles Bradlaugh took the Chiltern Hundreds in 1884 to seek a vote of confidence from his constituents, Lord Randolph Churchill and the Conservative press were highly critical of the Gladstone government for allowing Bradlaugh a new opportunity to demonstrate his popularity with the electors of Northampton.

Sections 24 and 25 of the Succession to the Crown Act 1707 listed ministerial offices as offices of profit. When an MP became a government minister, including Prime Minister, they also lost their seat in the House of Commons. Therefore, Ministers were required to regain their seats in Parliament by winning a ministerial by-election. The Re-election of Ministers Act 1919 made it unnecessary to be re-elected within nine months of a general election, and the Act was amended in 1926 to abolish ministerial by-elections entirely.

Sinn Féin resignations
On 20 January 2011, Sinn Féin MP Gerry Adams submitted a letter of resignation to the Speaker, but did not apply for a Crown office, which would be politically unacceptable for a Sinn Féin politician. On 26 January, a Treasury spokesperson said "Consistent with long-standing precedent, the Chancellor has taken [the letter] as a request to be appointed the Steward and Bailiff of the Manor of Northstead and granted the office." Although David Cameron said during Prime Minister's Questions that Adams had "accepted an office for profit under the Crown", Adams denied this; he continued to simply reject the title, albeit not its effect of removal from office.

Another Sinn Féin MP, Martin McGuinness, resigned and was formally appointed as Steward and Bailiff of the Manor of Northstead on 2 January 2013, leading to the 2013 Mid Ulster by-election. McGuinness also said that he rejected the title.

Law
The law relating to resignation is now codified and consolidated in section 4 of the House of Commons Disqualification Act 1975:

"For the purposes of the provisions of this Act relating to the vacation of the seat of a member of the House of Commons who becomes disqualified by this Act for membership of that House, the office of steward or bailiff of Her Majesty's three Chiltern Hundreds of Stoke, Desborough and Burnham, or of the Manor of Northstead, shall be treated as included among the offices described in Part III of Schedule 1 to this Act."

Schedule 1 lists actual offices that are disqualifying for membership in the House of Commons. Under Section 6, anyone appointed to those offices is prohibited from being elected to the House or continuing to sit in the House. However, the Stewardships of the Chiltern Hundreds and the Manor of Northstead are only included in Schedule 1 for the purpose of vacating the seat. Stewards can still be elected to the House of Commons after taking up their appointments.

Notice and orders
An MP applies for the office to the Chancellor of the Exchequer, who usually then signs a warrant appointing the MP to the Crown office. The appointee holds the office until such time as another MP is appointed, or they apply to be released. Sometimes this can be a matter of minutes, as on an occasion when three or more MPs apply on the same day. Once released, they are again free to seek election to the House of Commons.

When an MP is appointed to the post, the Treasury releases a public notice: "The Chancellor of the Exchequer has this day appointed [named individual] to be Steward and Bailiff of the (Three Hundreds of Chiltern / Manor of Northstead)."

After the Speaker has been notified, the appointment and resulting disqualification is noted in the Vote and Proceedings, the Commons' daily journal of proceedings:

Notification, laid upon the Table by the Speaker, That Mr Chancellor of the Exchequer had today appointed [named individual], Member for [named constituency], to the office of Steward and Bailiff of the Three Hundreds of Chiltern.

Thereafter, the former MP's party (or the Government, if they were independent or their party has no other MPs) moves for a writ of election to be issued calling for a by-election. The resulting order is in the following form:

Ordered, That the Speaker do issue his Warrant for the Clerk of the Crown to make out a new writ for the electing of a Member to serve in this present parliament for the [County Constituency] of [named area] in the room of the [Right Honourable] [named individual], who since election for the said [County Constituency] has been appointed to the (Office of Steward and Bailiff of His Majesty's Three Chiltern Hundreds of Stoke, Desborough and Burnham in the County of Buckingham/Office of Steward and Bailiff of His Majesty's Manor of Northstead in the County of York).

The wording of these announcements may vary.

Former offices
Other offices formerly used for the same purpose are:

 * Steward and Bailiff of the Manor of East Hendred, Berkshire. This stewardship was first used for parliamentary purposes in November 1763 by Edward Southwell, and was in more or less constant use until 1840, after which it disappeared. This manor comprised copyholds, the usual courts were held, and the stewardship was an actual and active office. The manor was sold by public auction in 1823, but in some manner the Crown retained the right of appointing a steward for seventeen years afterwards.
 * Steward of the Manor of Hempholme, Yorkshire. This manor appears to have been of the same nature as that of Northstead. It was in lease until 1835. It was first used for parliamentary purposes in 1845 and was in constant use until 1865. It was sold in 1866.
 * Escheator of Munster. Escheators were officers commissioned to secure the rights of the Crown over property which had legally escheated (forfeited) to it from those who had held land from the crown and had recently died (or been legally attainted). In Ireland mention is made of escheators as early as 1256. In 1605 the escheatorship of Ireland was split into four, one for each province, but the duties soon became practically nominal. The escheatorship of Munster was first used for parliamentary purposes in the Irish Parliament from 1793 to 1800, and in the united Parliament (24 times for Irish seats and once for a Scottish seat) from 1801 to 1820. After 1820 it was discontinued and finally abolished in 1838.
 * Steward of the Manor of Old Shoreham, Sussex. This manor belonged to the Duchy of Cornwall. It was first used for parliamentary purposes in 1756, and then, occasionally, until 1799, in which year it was sold by the Duchy to the Duke of Norfolk.
 * Steward of the Manor of Poynings, Sussex. This manor reverted to the Crown on the death of Lord Montague about 1804, but was leased until about 1835. It was only twice used for parliamentary purposes, in 1841 and 1843.
 * Escheator of Ulster. This appointment was used in the united Parliament three times, for Irish seats only; the last time in 1819.
 * February 1801: William Talbot (Kilkenny City)
 * March 1804: John Claudius Beresford (Dublin City)
 * February 1819: Richard Nevill (Wexford Borough)
 * Steward of the Honour of Otford, Kent. Used once in 1742 for Lord Middlesex (East Grinstead).
 * Chief Steward and Keeper of the Courts of the Honour of Berkhamsted, Hertfordshire, Buckinghamshire, and Northampton (part of the Duchy of Cornwall). Used once in 1752 for Henry Lascelles (Northallerton).
 * Steward of the Manor of Kennington, Surrey. Used once in 1757 for Thomas Duckett (Calne).
 * Steward of the Manor of Shippon, Berkshire. Used once in 1765 for Thomas Watson (Berwick-upon-Tweed).
 * A different kind of appointment, the militia agency, has also been used. For example, in 1770 Jervoise Clarke Jervoise was appointed to the office of agent to the regiment of militia of the county of Sussex, as a consequence of him not being able to be appointed to the customary stewardships at that time. Similar offices were used on at least two more occasions.

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


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Northstead

Northstead is an area on the North Bay of Scarborough in North Yorkshire, England. The area near Newlands and Barrowcliff includes Peasholm Park and Scarborough Open Air Theatre.

In 2011, the namesake ward had a population of 4,038. Since 2019 the ward no longer covers the area, with most of the old ward now in the Woodlands ward.

History
The Manor of Northstead consisted of a medieval manor house surrounded by fields and farms in the parish of Scalby in the North Riding of Yorkshire. The estate originally bordered the northern side of the ancient boundary of the Borough of Scarborough, following the line of Peasholm Beck. The estate passed into the ownership of the Crown during the reign of King Richard III (1483–1485). By 1600, the manor house had fallen into disrepair, being latterly occupied by Sir Richard Cholmeley's shepherd until it finally collapsed.

The land, but not the lordship of the manor, was bought from the Crown by the Scarborough Corporation in 1921. The manor house for the former estate no longer exists and the land has since been redeveloped as part of modern-day Scarborough. The site of the manor house is believed to have been covered by the lake in Peasholm Park, a municipal park opened in 1912.

Politics
The ancient title of the Crown Steward and Bailiff of the Manor of Northstead persisted beyond the manor, however, being used since the 19th century as a sinecure post which plays a role in the procedure for effecting Resignation from the House of Commons of the United Kingdom.

By virtue of the fact that it became and was retained as a Lordship of the Crown beyond the sale and eventual disappearance of the estate, since the 19th century the post of Crown Steward and Bailiff of the Manor of Northstead has played a role in the procedure for effecting Resignation from the House of Commons of the United Kingdom by Members of Parliament (MPs). While no longer having any actual role or responsibility, it remains a nominal paid office of the Crown, a sort of sinecure, appointment to which is one of the things that by law disqualifies an MP from the House. This principle goes back to the Act of Settlement 1701, and is now regulated by the House of Commons Disqualification Act 1975. Since 1623, MPs have not been permitted to resign their seats directly. Although several such offices have been used for this purpose in the past, in the present day only two are used: the Northstead post and that of Crown Steward and Bailiff of the three Chiltern Hundreds of Stoke, Desborough and Burnham.

Most references say that the Northstead post was first used in this way on 20 March 1844 to allow Sir George Henry Rose, Member for Christchurch, to resign his seat. But the official book recording appointments to the various stewardships (lodged in The National Archives under catalogue reference E 197/1 ) indicates that Patrick Chalmers, MP for Montrose Burghs, was appointed Steward of the Manor of Northstead on 6 April 1842. The writ of election for a replacement was moved as if Chalmers had been appointed to the Chiltern Hundreds.

Appointments to the posts are made by the Chancellor of the Exchequer. Using two posts allows more than one MP to resign simultaneously, although more commonly, single resignations are effected by alternating appointments to the Northstead and Chiltern Hundreds offices. One of the most recent MPs to be appointed to the Northstead office was former Prime Minister David Cameron, who announced his decision to resign from his parliamentary seat of Witney on 12 September 2016.

Appointment of Gerry Adams
Sinn Féin MP Gerry Adams was appointed to the post after announcing his intention to resign from the UK Parliament to stand in the 2011 Irish general election. Adams denied that he had accepted the appointment, which would conflict with Sinn Féin's longstanding policy of refusing to pledge allegiance to the British Crown. It was later clarified in Parliament that Adams had not "accepted" the post, but had been appointed to it on announcing his desire to resign as an MP.

title: Northstead


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USS Tennessee

Six ships of the United States Navy have been named USS Tennessee in honor of the 16th state.

 * SS Republic (1853), originally Tennessee, was a paddlewheel steamer captured from the Confederacy at New Orleans on 2 April 1862.
 * CSS Tennessee was a Confederate ironclad captured from the Confederacy in the Battle of Mobile Bay on 16 February 1864.
 * USS Tennessee (1865) was a wooden screw frigate originally built and named as Madawaska.
 * USS Tennessee (ACR-10) was the lead ship of her class of armored cruiser.
 * USS Tennessee (BB-43) was the lead ship of her class of battleship, was damaged in the Attack on Pearl Harbor, repaired and saw action in the Pacific during World War II, broken up 1959.
 * USS Tennessee (SSBN-734) is an Ohio-class submarine

title: USS Tennessee


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USS Vermont

Three ships of the United States Navy have been named USS Vermont in honor of the 14th state.

 * The first USS Vermont (1848) was one of nine ships of the line authorized by Congress in 1816, but it was not launched until 1848, and only ever saw service as a receiving ship, from 1862 to 1901.
 * The second USS Vermont (BB-20) was a Connecticut-class battleship
 * The third USS Vermont (SSN-792) is a Virginia-class submarine

title: USS Vermont


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Oil crisis

Oil crisis or oil shock may refer to:

 * Abadan Crisis ("Iran Oil Crisis") of 1951–1954 - nationalization, coup, and de-nationalisation in Iran
 * 1970s energy crisis
 * 1973 oil crisis, the first worldwide oil crisis, in which prices increased 400%
 * 1979 oil crisis, in which prices increased 100%
 * 1990 oil price shock (the "mini oil-shock"), in which prices increased for nine months
 * 2000s energy crisis
 * 2020 Russia–Saudi Arabia oil price war, in which prices declined more than 50%
 * 2022–2023 Russia–European Union gas dispute, in which EU member states sought to rapidly exclude natural gas imports from Russia following Russia's invasion of Ukraine
 * Peak oil, a hypothetical time in the future when oil production enters permanent decline

title: Oil crisis


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The Library of Babel

"The Library of Babel" (La biblioteca de Babel) is a short story by Argentine author and librarian Jorge Luis Borges (1899–1986), conceiving of a universe in the form of a vast library containing all possible 410-page books of a certain format and character set.

The story was originally published in Spanish in Borges' 1941 collection of stories El jardín de senderos que se bifurcan (The Garden of Forking Paths). That entire book was, in turn, included within his much-reprinted Ficciones (1944). Two English-language translations appeared approximately simultaneously in 1962, one by James E. Irby in a diverse collection of Borges's works titled Labyrinths and the other by Anthony Kerrigan as part of a collaborative translation of the entirety of Ficciones.

Plot
Borges' narrator describes how his universe consists of an enormous expanse of adjacent hexagonal rooms. In each room, there is an entrance on one wall, the bare necessities for human survival on another wall, and four walls of bookshelves. Though the order and content of the books are random and apparently completely meaningless, the inhabitants believe that the books contain every possible ordering of just 25 basic characters (22 letters, the period, the comma, and space). Though the vast majority of the books in this universe are pure gibberish, the library also must contain, somewhere, every coherent book ever written, or that might ever be written, and every possible permutation or slightly erroneous version of every one of those books. The narrator notes that the library must contain all useful information, including predictions of the future, biographies of any person, and translations of every book in all languages. Conversely, for many of the texts, some language could be devised that would make it readable with any of a vast number of different contents.

Despite—indeed, because of—this glut of information, all books are totally useless to the reader, leaving the librarians in a state of suicidal despair. This leads some librarians to superstitious and cult-like behaviors, such as the "Purifiers", who arbitrarily destroy books they deem nonsense as they scour through the library seeking the "Crimson Hexagon" and its illustrated, magical books. Others believe that since all books exist in the library, somewhere one of the books must be a perfect index of the library's contents; some even believe that a messianic figure known as the "Man of the Book" has read it, and they travel through the library seeking him.

Themes
The story repeats the theme of Borges' 1939 essay "The Total Library" ("La Biblioteca Total"), which in turn acknowledges the earlier development of this theme by Kurd Lasswitz in his 1901 story "The Universal Library" ("Die Universalbibliothek"):

"Certain examples that Aristotle attributes to Democritus and Leucippus clearly prefigure it, but its belated inventor is Gustav Theodor Fechner, and its first exponent, Kurd Lasswitz. [...] In his book The Race with the Tortoise (Berlin, 1919), Dr Theodor Wolff suggests that it is a derivation from, or a parody of, Ramón Llull's thinking machine [...] The elements of his game are the universal orthographic symbols, not the words of a language [...] Lasswitz arrives at twenty-five symbols (twenty-two letters, the space, the period, the comma), whose recombinations and repetitions encompass everything possible to express in all languages. The totality of such variations would form a Total Library of astronomical size. Lasswitz urges mankind to construct that inhuman library, which chance would organize and which would eliminate intelligence. (Wolff's The Race with the Tortoise expounds the execution and the dimensions of that impossible enterprise.)"

Many of Borges' signature motifs are featured in the story, including infinity, reality, cabalistic reasoning, and labyrinths. The concept of the library is often compared to Borel's dactylographic monkey theorem. There is no reference to monkeys or typewriters in "The Library of Babel", although Borges had mentioned that analogy in "The Total Library": "[A] half-dozen monkeys provided with typewriters would, in a few eternities, produce all the books in the British Museum." In this story, the closest equivalent is the line, "A blasphemous sect suggested [...] that all men should juggle letters and symbols until they constructed, by an improbable gift of chance, these canonical books." Borges makes an oblique reference to reproducing Shakespeare, as the only decipherable sentence in one of the books in the library, "O time thy pyramids", is surely taken from Shakespeare's Sonnet 123 which opens with the lines "No Time, thou shalt not boast that I do change, Thy pyramids...".

Borges would examine a similar idea in his 1976 story, "The Book of Sand", in which there is an infinite book (or book with an indefinite number of pages) rather than an infinite library. Moreover, the story's Book of Sand is said to be written in an unknown alphabet and its content is not obviously random. In The Library of Babel, Borges interpolates Italian mathematician Bonaventura Cavalieri's suggestion that any solid body could be conceptualized as the superimposition of an infinite number of planes.

The concept of the library is also overtly analogous to the view of the universe as a sphere having its center everywhere and its circumference nowhere. The mathematician and philosopher Blaise Pascal employed this metaphor, and in an earlier essay Borges noted that Pascal's manuscript called the sphere effroyable, or "frightful".

In any case, a library containing all possible books, arranged at random, might as well be a library containing zero books, as any true information would be buried in, and rendered indistinguishable from, all possible forms of false information; the experience of opening to any page of any of the library's books has been simulated by websites which create screenfuls of random letters.

The quote at the beginning of the story, "By this art you may contemplate the variation of the twenty-three letters," is from Robert Burton's 1621 The Anatomy of Melancholy.

Infinite extent
In mainstream theories of natural language syntax, every syntactically valid utterance can be extended to produce a new, longer one, because of recursion. However, the books in the Library of Babel are of bounded length ("each book is of four hundred and ten pages; each page, of forty lines, each line, of some eighty letters"), so the Library can only contain a finite number of distinct strings. Borges' narrator notes this fact, but believes that the Library is nevertheless infinite; he speculates that it repeats itself periodically, giving an eventual "order" to the "disorder" of the seemingly random arrangement of books. Mathematics professor William Goldbloom Bloch confirms the narrator's intuition, deducing in his popular mathematics book The Unimaginable Mathematics of Borges' Library of Babel that the library's structure necessarily has at least one room whose shelves are not full (because the number of books per room does not divide the total number of books evenly), and the rooms on each floor of the library must either be connected into a single Hamiltonian cycle, or possibly be disconnected into subsets that cannot reach each other.

Quine's reduction
W. V. O. Quine notes that the Library of Babel is finite, and that any text that does not fit in a single book can be reconstructed by finding a second book with the continuation. The size of the alphabet can be reduced by using Morse code even though it makes the books more verbose; the size of the books can also be reduced by splitting each into multiple volumes and discarding the duplicates. Writes Quine, "The ultimate absurdity is now staring us in the face: a universal library of two volumes, one containing a single dot and the other a dash. Persistent repetition and alternation of the two are sufficient, we well know, for spelling out any and every truth. The miracle of the finite but universal library is a mere inflation of the miracle of binary notation: everything worth saying, and everything else as well, can be said with two characters."

Comparison with biology
The full possible set of protein sequences (protein sequence space) has been compared to the Library of Babel. In the Library of Babel, finding any book that made sense was almost impossible due to the sheer number and lack of order. The same would be true of protein sequences if it were not for natural selection, which has picked out only protein sequences that make sense. Additionally, each protein sequence is surrounded by a set of neighbors (point mutants) that are likely to have at least some function. Daniel Dennett's 1995 book Darwin's Dangerous Idea includes an elaboration of the Library of Babel concept to imagine the set of all possible genetic sequences, which he calls the Library of Mendel, in order to illustrate the mathematics of genetic variation. Dennett uses this concept again later in the book to imagine all possible algorithms that can be included in his Toshiba computer, which he calls the Library of Toshiba. He describes the Library of Mendel and the Library of Toshiba as subsets within the Library of Babel.

Influence on later writers

 * Umberto Eco's postmodern novel The Name of the Rose (1980) features a labyrinthine library, presided over by a blind monk named Jorge of Burgos. The room is, however, octagonal in shape.
 * Russell Standish's Theory of Nothing uses the concept of the Library of Babel to illustrate how an ultimate ensemble containing all possible descriptions would in sum contain zero information and would thus be the simplest possible explanation for the existence of the universe. This theory, therefore, implies the reality of all universes.
 * The Unimaginable Mathematics of Borges' Library of Babel (2008) by William Goldbloom Bloch explores the short story from a mathematical perspective. Bloch analyzes the hypothetical library presented by Borges using the ideas of topology, information theory, and geometry.
 * In Greg Bear's novel City at the End of Time (2008), the sum-runners carried by the protagonists are intended by their creator to be combined to form a 'Babel', an infinite library containing every possible permutation of every possible character in every possible language. Bear has stated that this was inspired by Borges, who is also namechecked in the novel. Borges is described as an unknown Argentinian who commissioned an encyclopedia of impossible things, a reference to either "Tlön, Uqbar, Orbis Tertius" or the Book of Imaginary Beings.
 * The Library of Babel, a website created by Jonathan Basile, emulates an English-language version of Borges' library. An algorithm he created generates a "book" by iterating every permutation of 29 characters: the 26 English letters, space, comma, and period. Each book is marked by a coordinate, corresponding to its place on the hexagonal library (hexagon name, wall number, shelf number, and book name) so that every book can be found at the same place every time. The website is said to contain "all possible pages of 3200 characters, about 104677 books". For example, a coordinate may look like "389fj39l-w4-s5-v32" where, "389fj39l" is the hexagon name, "w4" specifies wall 4, "s5" specifies shelf 5, and "v32" specifies volume 32.
 * In Steven L. Peck's novella A Short Stay In Hell (2009), the protagonist must find the book of his life's story in a library containing every possible book. Borges' story is mentioned directly, although the library is structured very differently. It is also explicitly finite in size, though it is more than a million orders of magnitude larger than the observable universe.

title: The Library of Babel


text:
Caproni Campini N.1

The Caproni Campini N.1, also known as the C.C.2, is an experimental jet aircraft built in the 1930s by Italian aircraft manufacturer Caproni. The N.1 first flew in 1940 and was briefly regarded as the first successful jet-powered aircraft in history, before news emerged of the German Heinkel He 178's first flight a year earlier.

During 1931, Italian aeronautics engineer Secondo Campini submitted his studies on jet propulsion, including a proposal for a so-called thermo-jet to power an aircraft. Following a high-profile demonstration of a jet-powered boat in Venice, Campini was rewarded with an initial contract issued by the Italian government to develop and manufacture his proposed engine. During 1934, the Regia Aeronautica (the Italian Air Force) granted its approval to proceed with the production of a pair of jet-powered prototype aircraft. To produce this aircraft, which was officially designated as the N.1, Campini formed an arrangement with the larger Caproni aviation manufacturer.

The N.1 is powered by a motorjet, a type of jet engine in which the compressor is driven by a conventional reciprocating engine. On 27 August 1940, the first flight of the N.1 took place at the Caproni facility in Taliedo, outside of Milan, flown by Mario de Bernardi.

The N.1 achieved mixed results; while it was perceived and commended as a crucial milestone in aviation (until the revelation of the He 178's earlier flight), the performance of the aircraft was unimpressive. Specifically, it was slower than many existing conventional aircraft of the era, while the motorjet engine was incapable of producing sufficient thrust to deliver adequate performance for a fighter aircraft. As such, the N.1 programme never led to any operational combat aircraft, and the motorjet design was soon superseded by more powerful turbojets. Only one of the two examples of the N.1 to have been constructed has survived to the present day.

Background
During 1931, Italian aeronautics engineer Secondo Campini submitted a report to the Regia Aeronautica (the Italian Air Force) on the potential of jet propulsion; this report included his proposals for one such implementation, which he referred to as a thermo-jet. That same year, Campini established a company, with his two brothers, called the "Velivoli e Natanti a Reazione" (Italian for "Jet Aircraft and Boats") to pursue the development of this engine. In April 1932, the company demonstrated a pump-jet propelled boat in Venice, Italy. The boat achieved a top speed of 28 knot, a speed comparable to a boat with a conventional engine of similar output. The Italian Navy, who had funded the development of the boat, placed no orders but did veto the sale of the design outside of Italy.

During 1934, the Regia Aeronautica granted approval for the development of a pair of prototypes, along with a static testbed, for the purpose of demonstrating the principle of a jet aircraft, as well as to explore potential military applications. As his company lacked the necessary industrial infrastructure for such endeavours, Campini formed an arrangement with the larger Caproni aviation manufacturer, under which the latter provided the required material assistance for the manufacturing of the prototypes. Under this relationship, Campini developed his design, which later received the official Italian Air Force designation of N.1.

Historian Nathanial Edwards has contrasted the relative openness of Italian early jet development work against the high levels of secrecy present within other nation's programmes, such as Britain and Germany. He speculated that this was due to desire of the Italian government to be perceived as possessing a modern and advanced aviation industry, being keen to acquire national prestige and renown for such achievements. Edwards went onto claim that the practicality of the N.1 design was undermined by political pressure to speed the programme along so that Italy would be more likely to be the first country in the world to perform a jet-powered flight.

Design
The Caproni Campini N.1 is an experimental aircraft, designed to demonstrate the practicality of jet propulsion and its viability as an engine for aircraft. It was a monoplane built entirely out of duralumin, with an elliptical wing. The original design was to have the aircraft cockpit pressurised however this facility was never installed. The aircraft was fitted with dual controls allowing it to be flow from either of the two seats. Both seats had individual rearward sliding canopies however, flight testing quickly revealed that, due to the excessive heat output of the propulsion system, the canopy had to be left permanently open as a mitigating measure.

The engine of the N.1 differs substantially from the later-produced turbojet and turbofan engines. One crucial difference in Campini's design is that the compressor – a three-stage, variable-incidence one, located forward of the cockpit – was driven by a conventional piston engine, this being a 900 hp, liquid-cooled Isotta Fraschini unit. The airflow provided by the compressor was used to cool the engine before being mixed with the engine's exhaust gases, thus recovering most of the heat energy that in traditional piston-propeller designs would be wasted. A ring-shaped burner then injected fuel into the gas flow and ignited it, immediately before the exhaust nozzle, to further increase thrust.

In practice the engine provided enough thrust for flight without activating the rear burner, making the design somewhat similar to a ducted fan coupled to an afterburner. Campini referred to this configuration as being a thermojet, although it has since become commonly known as motorjet. However, despite the elaborate design, the relatively small size of the duct limited the mass flow and thus the propulsive efficiency of the engine. In modern designs this is offset through high overall pressure ratios, which could not be achieved on the N.1, therefore resulting in relatively low thrust and poor fuel efficiency. Ground tests performed with the static testbed produced a thrust of around 700 kgf.

Operational history
The N.1s first flight was made on 27 August 1940 by test pilot Mario De Bernardi at Caproni's facility in Taliedo, outside Milan. He would conduct the majority of the N.1's test flights. The first flight lasted ten minutes, during which de Bernardi kept the speed below 225 mph, less than half throttle.

Although the first flight of the jet-powered Heinkel He 178 had been made a year before to the day, it had not been made public, so the Fédération Aéronautique Internationale recorded the N.1 as the first successful flight by a jet aircraft.

Flight tests with the first prototype revealed several issues with the engine. It did not produce sufficient thrust to achieve the anticipated performance if it was matched to a strengthened airframe to withstand the high loading pressures. The engine generated considerable heat, which forced the pilot to fly with the canopy open throughout the flight, which although effectively venting the heat, increased drag. According to aviation author Sterling Michael Pavelec the N.1 was "heavy and underpowered" and the conventionally-powered Caproni Vizzola F.4 was faster which he attributed to limited national resources which left development programs underfunded.

On 30 November 1941 the second prototype (Caproni construction No 4850) was flown by de Bernardi, with Giovanni Pedace as a passenger, from Milan's Linate Airport to Rome's Guidonia Airport. During the flight adverse weather caused a diversion and resulting in an unplanned flight over Pisa. On 5 December 1941, de Bernardi made a flight over central Rome following a request from Benito Mussolini. On 6 December 1941, Mussolini inspected the aircraft and watched de Bernardi demonstrate its capabilities.

Testing of the first Caproni Campini N.1 prototype (Caproni construction No 4849) by the Italian military took place from December 1941 to August of 1942 with the aircraft receiving its military serial number (MM.487) on 30 December 1941. During the test program the aircraft was regularly shown off to foreign delegations. The last known flight by a Caproni Campini N.1 took place on the 27 August 1942. In June 1944, MM.487 was found by Allied forces in its hangar at Guidonia airport. The aircraft was badly damaged either from allied bombing raids or by the retreating Germans. The damaged prototype was transported to the United Kingdom for study at the Royal Aircraft Establishment (RAE) in Farnborough. The aircraft was later scrapped at RAF Newton in 1949. The other example MM.448 (Caproni construction No 4850) survived the war in excellent condition.

Further Developments
A variant of the Yokosuka MXY-7 Ohka, built in japan towards the end of WW2, was powered by a Ishikawajima Tsu-11 motorjet based on Campini's design. The Soviets were influenced by reports of the Campini Caproni N1 and developed Kholshchevnikov VRDK motorjet engine which was used in the Mikoyan-Gurevich I-250 and the Sukhoi Su-5 aircraft. The Caproni company proposed a development of their Reggiane Re.2005 Sagittario single-seat fighter with small auxiliary 370 h.p. engine used to drive two centrifugal compressors. One compressor was to be used for supercharging the main Daimler-Benz DB 605 engine, and the auxiliary unit, while the second would be used to provide reaction propulsion.

Surviving aircraft
The surviving example is now on display at the Italian Air Force Museum at Vigna di Valle, near Rome, while the ground testbed, consisting of only the fuselage, is on display at the National Museum of Science and Technology in Milan.

title: Caproni Campini N.1


text:
OK (disambiguation)

OK is a word expressing approval or assent. OK or Ok may also refer to:
 * OK (gesture)

Albums

 * Okay (album), by As It Is, 2017
 * OK (Chang Chen-yue album), 2007
 * OK (The Fall of Troy album), 2016
 * O.K. (Gabby's World album), 2015
 * O.K. (Kool A.D. album), 2015
 * OK (Talvin Singh album), 1998
 * OK, by Gazzelle, 2021

Songs

 * "OK" (Big Brovaz song), 2003
 * "OK" (Farin Urlaub song), 2002
 * "OK" (Robin Schulz song), 2017
 * "OK", by Backstreet Boys from DNA, 2019
 * "Ok", by Beastie Boys from Hot Sauce Committee Part Two, 2011
 * "OK", by Eels from Earth to Dora, 2020
 * "OK", by Fujiya & Miyagi from Ventriloquizzing, 2011
 * "Ok", by Helena Paparizou from Protereotita, 2004
 * "OK", by Iyaz from Replay, 2010
 * "OK!", by Jauz and San Holo, 2016
 * "OK", by Madeon from Adventure, 2015
 * "OK", by Meg from Beam, 2007
 * "OK", by Nav from Bad Habits, 2019
 * "OK!", by NCT from Universe, 2021
 * "OK!", a Pokémon theme song
 * "O.K.?", from the Rock Follies of '77 soundtrack, 1977
 * "OK", by Sam Ryder from There's Nothing but Space, Man!, 2022
 * "OK", by Wallows, 2020
 * "OK (Anxiety Anthem)", by Mabel from High Expectations, 2019

Other entertainment

 * Okay (band) or O.K., a 1980s German pop act
 * Organized Konfusion or OK, a hip hop act
 * o.k. (film), a 1970 West German anti-Vietnam War film by Michael Verhoeven
 * OK!, a British celebrity tabloid
 * OK! TV, a program affiliated with the magazine

Language

 * Ok languages, a family of languages spoken in New Guinea
 * Old Korean, the earliest attested stage of the Korean language

People

 * Ok (Korean name), a family and given name, including a list of people with the name
 * Ok (Turkish surname), list of people with the surname

Places

 * Ok (volcano), a shield volcano in Iceland
 * O.K. Range, a mountain range in British Columbia, Canada
 * O K, Kentucky, US
 * Oklahoma, United States postal abbreviation

Products and companies

 * OK FM Legaspi (DWGB), a Filipino radio station
 * OK FM Naga (DZOK), a Filipino radio station
 * OK Kosher Certification, a food-products certification agency
 * OK Motor Services, a defunct bus and coach operator in County Durham, England
 * OK Sauce, a fruity brown sauce
 * OK Soda, a soft drink
 * OK-Supreme, a British motorcycle manufacturer
 * OKs, a cereal formerly produced by Kellogg's
 * Circle K, a convenience store chain known as OK in Macau, Hong Kong, and (formerly) Taiwan
 * Czech Airlines (IATA code)
 * Odnoklassniki, a social network service used mainly in Russia

Sports

 * OK (dinghy), a class of racing dinghy
 * OK League, a defunct South African football league
 * OK Liga, a Spanish men's rink hockey league
 * OK Liga Femenina, a Spanish women's rink hockey league

Other uses

 * OK cells, a cell line derived from North American opossum kidney
 * O.K. Corral (building), a historic structure in Tombstone, Arizona, US
 * Gunfight at the O.K. Corral, an 1881 shootout in an area near the O.K. Corral
 * OK Hotel, a bar and music venue in Seattle, Washington, US
 * One Kamerun, a political party in Cameroon
 * OK, the ring of integers of an algebraic number field K

title: OK (disambiguation)


text:
Talk:OK (disambiguation)

Comments
This was a redirector to Talk:Okay, so there was nowhere to discuss the dab page OK. I've just removed the redirect --ColinFine 22:26, 6 May 2007 (UTC)

OK= Ola Karlaug (a great norwegian hero)Liverpoolola (talk) 20:40, 15 February 2009 (UTC)

Queensland
I've just removed an entry for a 'town in the Chillagoe district' in Queensland. There is indeed an OK Mine and Smelter at Chillagoe, but it is not a town, and since it is not apparently notable enough for anybody to have created a WP article for it so far, it does not seem likely to be something that anybody would come looking for on a disambiguation page. --ColinFine 22:31, 6 May 2007 (UTC)

Redlink
Removed from the dab page because there was no article to link to:

 * Oljekompaniet, a Swedish oil company

-- Shelf Skewed  Talk  16:19, 17 October 2007 (UTC)

OK Computer
A dab page is not an index to everything that contains the dabbed term. It is used to differentiate among articles that might use the same title. If OK Computer were an article about a computer (or store or company) named OK, it would be a valid entry on this page. But it's not; it's about an album named OK Computer and so doesn't require disambiguation from things named "OK". Ask yourself: Are users searching for this album likely to enter just "OK" in the search box and expect to end up at the article for OK Computer? Or, rather, are they going to enter "OK Computer"? And if we add this album, will we also be adding OK Calculator (album), OK Cobra (group), OK Connery (film), OK Cowboy (album), OK Go (band), OK Jazz (band), and OK to Go (album)? -- Shelf Skewed  Talk  13:05, 7 January 2008 (UTC)
 * I'd disagree with you on the very first point; any page which might be arrived at directly by someone searching for information - as OK is - needs to have not only the 'pure' dab items, but also the 'logical connections' ones too, hence there is an existing In other uses: section. Ideally OK Computer should be in this latter section, however as there is already in music section someone put it there instead, for fairly obvious reasons. All of those other links you list (where, incidentally, someone might abbreviate the name to just the 'OK' as a shorthand) seem sensible to add to the In other uses: section I would have thought. --AlisonW (talk) 15:55, 7 January 2008 (UTC)
 * If you disagree with my first point, you'll need to take that up at the Disambiguation talk page. And the other uses section is, again, for things named OK: a soda named OK, a league named OK, a company named OK, etc. The further uses you are thinking of are accomodated here by the Lookfrom links: To find other things that begin with OK. And does anyone really refer to OK Computer as OK? I love the album, and I own it, and I've never called it OK—I call it OK Computer. Ditto the band OK Go. I rather doubt your contention that anyone refers to any of those other things I listed as OK for short. -- Shelf Skewed  Talk  16:11, 7 January 2008 (UTC)
 * Is this the Ok Corral? Looks like a gunfight! Why isn't the Ok Corral mentioned? - Secondarywaltz (talk) 21:56, 7 January 2008 (UTC)
 * Oh! It is listed under, just as OK Computer is listed under . Hope this helps. - Secondarywaltz (talk) 22:03, 7 January 2008 (UTC)

fro
http://en.wikipedia.org/wiki/Image:3-Tastenmaus_Microsoft.jpg —Preceding unsigned comment added by 68.239.230.182 (talk) 23:50, 19 August 2008 (UTC)

http://en.wikipedia.org/wiki/Image:3-Tastenmaus_Microsoft.jpg —Preceding unsigned comment added by 68.239.230.182 (talk) 23:51, 19 August 2008 (UTC)

Also ,,ok,, ist eine abkürzung von otto kaiser der früher die auto kontrollierte und wenn ein auto korrekt war schrieb er sein namen hinn otto kaiser und dass wurde dann  zu o.k.... —Preceding unsigned comment added by 85.94.233.188 (talk) 22:40, 21 July 2009 (UTC)

Exact abbreviation of OK
```` I wish to know that what's exactly the abbreviation of OK...???? —Preceding unsigned comment added by 115.186.128.22 (talk) 14:50, 27 January 2010 (UTC)

 * There is no abbreviation for OK--that's as brief as it gets. The article to consult for more information is Okay.-- Shelf Skewed  Talk  15:22, 27 January 2010 (UTC)
 * And after looking at that article, I stand corrected: OK can be shortened to K, if you like.-- Shelf Skewed  Talk  15:28, 27 January 2010 (UTC)

OK. Hello my name is Andreas and today I decided to have a look at what the wikipedia says about the definition of the expression 'OK' and see if it is related to what I have heard about the definition of this expression. I know that the definition of the 'OK' expression comes from the greek words 'ola kala'(όλα καλά) which means 'everything well'. I think that makes more sence than coming from names of historical persons. I do not know if I am wrong but it makes sence to me according to the fact that many english words and expressions have greek origins. Thanks — Preceding unsigned comment added by Andreasskevoulis (talk • contribs) 20:48, 27 May 2011 (UTC)

Definition of the expression: 'OK'
Hello my name is Andreas and today I decided to have a look at what the wikipedia says about the definition of the expression 'OK' and see if it is related to what I have heard about the definition of this expression. I know that the definition of the 'OK' expression comes from the greek words 'ola kala'(όλα καλά) which means 'everything well'. I think that makes more sence than coming from names of historical persons. I do not know if I am wrong but it makes sence to me according to the fact that many english words and expressions have greek origins. Thanks — Preceding unsigned comment added by Andreasskevoulis (talk • contribs) 20:50, 27 May 2011 (UTC)
 * The page OK is a disambiguation page, not an article. The issue you raise is relevant to the article Okay, where the origin of the term is discussed, so you should bring this up at Talk:Okay. Cheers!-- Shelf Skewed  Talk  03:51, 28 May 2011 (UTC)

10 October 2011 Some say that OK came from the Civil War Era. When Confederate troops came back from patrol with O casualties. They would write "0.K,meaning o killed, and all is well. From then on, "OK" became a widely accepted in it it's use meaning all is well. The information is strictly here say and should be treated as such.  — Preceding unsigned comment added by 24.9.194.2 (talk) 18:10, 10 October 2011 (UTC)

I apolagize in advance for how im doing this but im not a regular wikipedian. the previous statement is somewhat correct in its origins but OK comes from the words Oll Korect (general andrew jaxson) simply finding and looking at one of his orders during the civil war will verify this. previously we didnt say things how they were spelt but spell them how they were said. with the country accent of general jaxson it sounded oll korect and because of the war time was short so he would abreviate "all correct" as O.K. on his orders and documents. This is also where it gets its meaning from. okie dokie was also adopted later in the whitehouse by another representative. we also get the spelling of OKay in a similar manner of someone trying to spell O K as O Kay which later mutated (as time and dictionaries tend to do) to Okay. I wish i had the time to do all the research for this and other corrections but I have a job/college/studying for more certifications so if someone would please assist I would much appreciate it as ive been trying to find the time just to post this much for a few years... -M4dH4TT3r — Preceding unsigned comment added by M4dH4TT3r777 (talk • contribs) 03:22, 29 April 2012 (UTC)
 * Please see ShelfSkewed's comment above: this is not the place to discuss this. Please see Okay, and if you wish to discuss the content of that page, post on Talk:Okay. --ColinFine (talk) 15:30, 29 April 2012 (UTC)

Should this page be protected?
I've seen a whole lot of vandalism on this page recently, and I thought I would bring up the suggestion of it being a protected page? It would remove the hassle of having to undo so much vandalism. Just a thought. Traveller QLD  (talk | contribs) 15:17, 28 October 2012 (UTC)

Move discussion in progress
There is a move discussion in progress on Talk:Okay which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 01:59, 1 June 2014 (UTC)

title: Talk:OK (disambiguation)


text:
Lake Pontchartrain

Lake Pontchartrain is an estuary located in southeastern Louisiana in the United States. It covers an area of 630 sqmi with an average depth of 12 to 14 ft. Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about 40 mi from west to east and 24 mi from south to north.

In descending order of area, the lake is located in parts of six Louisiana parishes: St. Tammany, Orleans, Jefferson, St. John the Baptist, St. Charles, and Tangipahoa. The water boundaries were defined in 1979 (see list of parishes in Louisiana).

The lake is crossed by the Lake Pontchartrain Causeway, the longest continuous bridge over water in the world. A power line also crosses the lake. Its towers stand on caissons in Lake Pontchartrain, and its length can be used to visually demonstrate the curvature of the Earth.

Toponymy
Lake Pontchartrain is named for Louis Phélypeaux, comte de Pontchartrain. He was the French Minister of the Marine, Chancellor, and Controller-General of Finances during the reign of France's "Sun King", Louis XIV, for whom the colony of La Louisiane was named.

The name Pontchartrain itself comes from the place in France where Phélypeaux's château is situated. It is thought that this name originates from it being where a bridge (pont) crossed the river Mauldre on the ancient route from Lutèce to Chartres (chartrain).

Lake Maurepas, directly west of Lake Pontchartrain, was named for the son of Louis Phélypeaux, Jean-Frédéric Phélypeaux, comte de Maurepas, who was also a French statesman.

Description
Lake Pontchartrain is an estuary connected to the Gulf of Mexico via the Rigolets strait (known locally as "the Rigolets") and Chef Menteur Pass into Lake Borgne, another large lagoon, and therefore experiences small tidal changes. It receives fresh water from the Tangipahoa, Tchefuncte, Tickfaw, Amite, and Bogue Falaya rivers, and from Bayou Lacombe and Bayou Chinchuba. It is one of the largest wetlands along the Gulf Coast of North America. It comprises more than 125,000 acres of wetland, including bottomland hardwoods and cypress swamps (although these have been severely degraded by past logging), along with a complex mixture of herbaceous wetlands including fresh, intermediate, and brackish marsh. Lake Pontchartrain itself is part of the larger Pontchartrain Basin, a 10,000 square mile watershed that includes 16 Louisiana parishes and 4 Mississippi counties. The Basin is one of the largest estuarine systems of the Gulf of Mexico. The Pontchartrain Basin includes Lake Pontchartrain and the drainage area of its tributary streams, Lake Maurepas and the drainage area of its tributaries, The Rigolets, Lake Borgne, the Biloxi Marsh and Chandeleur Sound.

Salinity in Lake Pontchartrain varies from negligible at the northern cusp west of Mandeville up to nearly half the salinity of seawater at its eastern bulge near Interstate 10. Lake Maurepas, a true freshwater lake, connects with Lake Pontchartrain on the west via Pass Manchac. The Industrial Canal connects the Mississippi River with the lake at New Orleans. Bonnet Carré Spillway diverts water from the Mississippi into the lake during times of river flooding.

History
The lake was formed 2,600 to 4,000 years ago as the evolving Mississippi River Delta formed its southern and eastern shorelines with alluvial deposits. Human habitation of the region began at least 3,500 years ago. One recorded Indigenous name for the lake is Okwata ('wide water').

Habitation increased rapidly with the arrival of Europeans; in 1699, French explorer Pierre Le Moyne d'Iberville renamed the Lake Pontchartrain after Louis Phélypeaux, comte de Pontchartrain.

In 1777, the great American naturalist, William Bartram, explored the north shore during a trip west. In 1852, a railroad was constructed to link New Orleans to the north. Engines turned at Pass Manchac. However, the pilings were burned to the water line in the Civil War.

During the early 20th century, the great cypress swamps of the area were heavily logged and many have not regrown.

After over 30 years of oil drilling had yielded just 12 million barrels of oil and condensate and 119 billion cubic feet of natural gas, and caused major pollution of the lake, the State Mineral Board enacted a moratorium on oil drilling. As of 2009, there were 4 active wells continuing prior leases, and 25 derelict wells. According to the Louisiana Department of Environmental Quality (LDEQ) they and the US Coast Guard see at least one oil spill per day in Louisiana's wetlands. Estuarine wetlands are among the highest on the Environmental sensitivity Index (ESI).

Conservation and restoration
Owing to past exploitation, the ecosystems of the lake have been placed under stress. Marshes, for example, are turning to open water, and cypress swamps are being killed by saltwater intrusion. However, brown pelicans and bald eagles, once scarce, were a common sight along the shores as of 2004. A team of experts assembled by The Nature Conservancy assessed the situation in 2004 and identified seven target habitat types in particular need of conservation management: bottomland hardwood forest, cypress swamp, relict ridge woodland, fresh/intermediate marsh, brackish/salt marsh, lake open water, and littoral submersed aquatic vegetation. The bottomland hardwood forest and cypress swamp are suffering from a lack of freshwater input and sediment deposition owing to the levees upstream from the lake. In addition, bottomland hardwoods are being invaded by exotic species such as Chinese tallow, while freshwater marshes are being invaded by exotic species such as elephant's-ear. The team identified four key animal species which could indicate the degree to which the system declines or improves. These were the rangia clam (representing lake bottom habitat), gulf sturgeon and paddlefish (representing fish communities), and the alligator snapping turtle (one of the largest freshwater turtles in the world, but in decline owing to over-harvesting).

The future of the lake depends, in part, on restoring annual spring floods to the wetlands of the lake basin and controlling urban sprawl on the north shore. Selected species, like the paddlefish and alligator snapping turtle, would benefit from reduced harvesting. The lake could change considerably without such conservation planning. As of 2007, a few examples of future change included more cypress swamps converting to anthropogenic marsh or open water, Chinese tallow displacing native forests, and, with a warming climate, mangrove trees replacing brackish marsh. Hence, the ecosystems of the lake now, and in the future, depend very much upon some basic decisions about human activities in the vicinity of the lake, and, even more so, human activity upstream along the Mississippi River.

As of 2006, the population in the region was over 1.5 million. There have been many problems with the conservation management of forests and wetlands. As of 1995, the United States Geological Survey was monitoring the environmental effects of shoreline erosion, loss of wetlands, pollution from urban areas and agriculture, saltwater intrusion from artificial waterways, dredging, basin subsidence and faulting, storms and sea level rise, and freshwater diversion from the Mississippi and other rivers. With proper management of this lake and its wetlands, there is great potential to enhance the productivity of wetlands, and to maintain biological diversity to support an ecotourism industry that will diversify the economy.

Northshore

The area north of Lake Pontchartrain is known as the North Shore or the Northshore. It includes the cities of Mandeville, Covington, Abita Springs, Madisonville, Pearl River, Lacombe, and Slidell in St. Tammany Parish; Ponchatoula, Hammond, Amite, and Kentwood in Tangipahoa Parish; and Bogalusa and Franklinton in Washington Parish.

These three Northshore parishes are the eastern Florida Parishes. The landscape here is mostly uplands that were once dominated by long leaf pine savannas and interrupted by occasional large rivers. The savannas were maintained by regular fires caused by lightning; they produced the distinctive fauna and flora of this region.

Lake Pontchartrain's south shore areas (dominated by New Orleans), instead of being designated by that name, are more likely to be referred to as either "East bank" or "West bank," depending upon their position with respect to the general north–south course of the Mississippi River. Lake Pontchartrain forms the northern boundary of the city of New Orleans, which is coterminous with Orleans Parish, and the northern boundary of its two largest suburbs, Metairie and Kenner; as well as forming the northern boundaries of Jefferson Parish and Saint Charles Parish, and much of the northern and eastern boundaries of Saint John the Baptist Parish.

New Orleans
New Orleans was established at a Native American portage between the Mississippi River and Lake Pontchartrain. The lake provides numerous recreational activities for people in New Orleans and is also home to the Southern Yacht Club. In the 1920s, the Industrial Canal in the eastern part of the city opened, providing a direct navigable water connection, with locks, between the Mississippi River and the lake. In the same decade, a project dredging new land from the lake shore behind a new concrete floodwall began; this would result in an expansion of the city into the former swamp between Metairie/Gentilly Ridges and the lakefront. The Lake Pontchartrain Causeway was constructed in the 1950s and 1960s, connecting New Orleans (by way of Metairie) with Mandeville, and bisecting the lake in a north-northeast line.

Hurricanes
During hurricanes, a storm surge can build up in Lake Pontchartrain. Wind pushes water into the lake from the Gulf of Mexico as a hurricane approaches from the south, and from there it can spill into New Orleans.

A hurricane in 1947 flooded much of Metairie, much of which is slightly below sea level due to land subsidence after marshland was drained. After the storm, hurricane-protection levees were built along Lake Pontchartrain's south shore to protect New Orleans and nearby communities. A storm surge of 10 ft from Hurricane Betsy overwhelmed some levees in eastern New Orleans in 1965, while a storm surge funneled in by the Mississippi River–Gulf Outlet Canal and a levee failure flooded most of the Lower 9th Ward. After this the levees encircling the city and outlying parishes were raised to heights of 14 to 23 ft. Due to cost concerns, the levees were built to protect against only a Category 3 hurricane; however, some of the levees initially withstood the Category 5 storm surge of Hurricane Katrina (August 2005), which only slowed to Category 3 winds within hours of landfall (due to a last-minute eyewall replacement cycle).

Experts using computer modeling at Louisiana State University after Hurricane Katrina have concluded that the levees were never topped but rather faulty design, inadequate construction, or some combination of the two were responsible for the flooding of most of New Orleans. Some canal walls leaked underneath because the wall foundations were not deep enough in peat-subsoil to withstand the pressure of higher water.

Funding
Congress failed to fully fund an upgrade requested during the 1990s by the Army Corps of Engineers, and funding was cut in 2003–04 despite a 2001 study by the Federal Emergency Management Agency warning that a hurricane in New Orleans was one of the country's three most likely disasters. Raising and reinforcing the levees to resist a Category 5 hurricane might take 25 years to complete. Some estimates place the cost at $25 billion.

Hurricane Katrina

When Hurricane Katrina reached Category 5 in 2005, some experts predicted that the levee system might fail completely if the storm passed close to the city. Although Katrina weakened to a Category 3 before making landfall on August 29 (with only Category 1-2 strength winds in New Orleans on the weaker side of the eye of the hurricane), the outlying New Orleans East area along south Lake Pontchartrain was in the eyewall with winds, preceding the eye, nearly as strong as those experienced in Bay St. Louis, Mississippi. Canals near Chalmette began leaking at 8 am, and some levees/canals, designed to withstand Category 3 storms, suffered multiple breaks the following day (see Effects of Hurricane Katrina in New Orleans), flooding 80% of the city.

The walls of the Industrial Canal were breached by storm surge via the Mississippi River Gulf Outlet, while the 17th Street Canal and London Avenue Canal experienced catastrophic breaches, even though water levels never topped their flood walls. Louisiana State University experts presented evidence that some of these structures might have had design flaws or faulty construction.

There are indications that the soft earth and peat underlying canal walls may have given way. In the weeks before Katrina, tests of salinity in seepage pools near canals showed them to be lake water, not fresh water from broken mains. The 5.5 mi I-10 Twin Span Bridge heading northeast between New Orleans and Slidell was destroyed. The shorter Fort Pike Bridge crossing the outlet to Lake Borgne remained intact.

Much of the northern sector of the suburban areas of Metairie and Kenner was flooded with up to 2 to 3 ft of water. In this area, flooding was not the result of levee overtopping but was due to a decision by the governmental administration of Jefferson Parish to abandon the levee-aligned drainage pumping stations. This resulted in the reverse flow of lake water through the pumping stations into drainage canals which subsequently overflowed, causing extensive flooding of the area between I-10 and the lakefront. When the pump operators were returned to their stations, water was drained out of Metairie and Kenner in less than a day. On September 5, 2005, the Army Corps of Engineers started to fix levee breaches by dropping huge sandbags from Chinook helicopters. The London Avenue Canal and Industrial Canal were blocked at the lake as permanent repairs started. On September 6, the Corps began pumping flood water back into the lake after seven days in the streets of New Orleans. Because it was fouled with dead animals, sewage, heavy metals, petrochemicals, and other dangerous substances, the Army Corps worked with the U.S. Environmental Protection Agency and Louisiana Department of Environmental Quality (LDEQ) to avoid major contamination and eutrophication of the lake.

Aerial photography suggests that 25 e9USgal of water covered New Orleans as of September 2, which equals about 2% of Lake Pontchartrain's volume. Due to a lack of electric power, the city was unable to treat the water before pumping it into the lake. It is unclear how long the pollution will persist and what its environmental damage to the lake will be, or what the long-term health effects will be in the city from mold and other contamination.

On September 24, 2005, Hurricane Rita did not breach the temporary repairs in the main part of the city, but the repair on the Industrial Canal wall in the Lower 9th Ward was breached, allowing about 2 ft of water back into that neighborhood.

Notable deaths

 * Eastern Air Lines Flight 304 crashed into the lake on February 25, 1964, resulting in the deaths of 51 passengers and 7 crew.
 * On June 16, 1964, a Trailways bus plunged off the Lake Pontchartrain Causeway into Lake Pontchartrain, killing 6.
 * On December 31, 1967, a chartered plane crashed into Lake Pontchartrain, killing 5 servicemen and the pilot.
 * On September 15, 1978, six-year-old Benjamin Daly, along with the pilot, died when a private plane his parents had chartered crashed into the lake. His parents survived.
 * On February 23, 1980, a twin-engine plane crashed into Lake Pontchartrain, killing 7.
 * On January 15, 1981, a Piper PA-23 flying in heavy fog crashed into Lake Pontchartrain while on final approach to New Orleans Lakefront Airport, killing the plane's owner and pilot Joyce W. Hornady, the 73-year-old CEO of Hornady Manufacturing Company, and two other company employees Edward A. Heers, a 34-year-old engineer, and James W. Garber, a 29-year-old customer service manager.  All three men were due to attend and represent their company in the 1981 SHOT Show in New Orleans.
 * In 1986, a decomposing woman's body was found by two fishermen. The cause of death was homicide by asphyxia. She was not identified and no leads were ever identified in the case.
 * New England Patriots defensive end, New Orleans native, and former LSU star Marquise Hill was found dead in Lake Pontchartrain on May 28, 2007.
 * A U.S. Navy T-34 training plane crashed into the lake on January 23, 2010, after a routine training mission. The instructor, Lt. Clinton Wermers, was found dead at 0100 on January 27, 2010. The student pilot was rescued about two hours after the crash.

title: Lake Pontchartrain


text:
Torii

A torii (鳥居) is a traditional Japanese gate most commonly found at the entrance of or within a Shinto shrine, where it symbolically marks the transition from the mundane to the sacred, and a spot where kami are welcomed and thought to travel through.

The presence of a torii at the entrance is usually the simplest way to identify Shinto shrines, and a small torii icon represents them on Japanese road maps and on Google Maps.

The first appearance of torii gates in Japan can be reliably pinpointed to at least the mid-Heian period; they are mentioned in a text written in 922. The oldest existing stone torii was built in the 12th century and belongs to a Hachiman shrine in Yamagata Prefecture. The oldest existing wooden torii is a ryōbu torii (see description below) at Kubō Hachiman Shrine in Yamanashi Prefecture built in 1535.

Torii gates were traditionally made from wood or stone, but today they can be also made of reinforced concrete, stainless steel or other materials. They are usually either unpainted or painted vermilion with a black upper lintel. Shrines of Inari, the kami of fertility and industry, typically have many torii because those who have been successful in business often donate torii in gratitude. Fushimi Inari-taisha in Kyoto has thousands of such torii, each bearing the donor's name.

Uses

The function of a torii is to mark the entrance to a sacred space. For this reason, the road leading to a Shinto shrine (sandō) is almost always straddled by one or more torii, which are therefore the easiest way to distinguish a shrine from a Buddhist temple. If the sandō passes under multiple torii, the outer of them is called ichi no torii (一の鳥居). The following ones, closer to the shrine, are usually called, in order, ni no torii (二の鳥居) and san no torii (三の鳥居). Other torii can be found farther into the shrine to represent increasing levels of holiness as one nears the inner sanctuary (honden), core of the shrine. Also, because of the strong relationship between Shinto shrines and the Japanese Imperial family, a torii stands also in front of the tomb of each Emperor.

In the past torii must have been used also at the entrance of Buddhist temples. Even today, as prominent a temple as Osaka's Shitennō-ji, founded in 593 by Shōtoku Taishi and the oldest state-built Buddhist temple in the country (and world), has a torii straddling one of its entrances. (The original wooden torii burned in 1294 and was then replaced by one in stone.) Many Buddhist temples include one or more Shinto shrines dedicated to their tutelary kami ("Chinjusha"), and in that case a torii marks the shrine's entrance. Benzaiten is a syncretic goddess derived from the Indian divinity Sarasvati, who unites elements of both Shinto and Buddhism. For this reason halls dedicated to her can be found at both temples and shrines, and in either case in front of the hall stands a torii. The goddess herself is sometimes portrayed with a torii on her head. Finally, until the Meiji period (1868–1912) torii were routinely adorned with plaques carrying Buddhist sutras.

Yamabushi, Japanese mountain ascetic hermits with a long tradition as mighty warriors endowed with supernatural powers, sometimes use as their symbol a torii.

The torii is also sometimes used as a symbol of Japan in non-religious contexts. For example, it is the symbol of the Marine Corps Security Force Regiment and the 187th Infantry Regiment, 101st Airborne Division and of other US forces in Japan. It is also used as a fixture at the entrance of some Japantown communities, such as Liberdade in São Paulo.

Origins
The origins of the torii are unknown and there are several different theories on the subject, none of which has gained universal acceptance. Because the use of symbolic gates is widespread in Asia—such structures can be found for example in India, China, Thailand, Korea, and within Nicobarese and Shompen villages—many historians believe they may be an imported tradition.

They may, for example, have originated in India from the torana gates in the monastery of Sanchi in central India. According to this theory, the torana was adopted by Shingon Buddhism founder Kūkai, who used it to demarcate the sacred space used for the homa ceremony. The hypothesis arose in the 19th and 20th centuries due to similarities in structure and name between the two gates. Linguistic and historical objections have now emerged, but no conclusion has yet been reached.

In Bangkok, Thailand, a Brahmin structure called Sao Ching Cha strongly resembles a torii. Functionally, however, it is very different as it is used as a swing. that was constructed in 1784 in front of the Devasathan shrine by King Rama I. During the reign of Rama II the swing ceremony was discontinued as the swing had become structurally damaged by lightning.

Other theories claim torii may be related to the pailou of China. These structures however can assume a great variety of forms, only some of which actually somewhat resemble a torii. The same goes for Korea's "hongsal-mun". Unlike its Chinese counterpart, the hongsal-mun does not vary greatly in design and is always painted red, with "arrowsticks" located on the top of the structure (hence the name).

Various tentative etymologies of the word torii exist. According to one of them, the name derives from the term tōri-iru (通り入る).

Another hypothesis takes the name literally: the gate would originally have been some kind of bird perch. This is based on the religious use of bird perches in Asia, such as the Korean sotdae (솟대), which are poles with one or more wooden birds resting on their top. Commonly found in groups at the entrance of villages together with totem poles called jangseung, they are talismans which ward off evil spirits and bring the villagers good luck. "Bird perches" similar in form and function to the sotdae exist also in other shamanistic cultures in China, Mongolia and Siberia. Although they do not look like torii and serve a different function, these "bird perches" show how birds in several Asian cultures are believed to have magic or spiritual properties, and may therefore help explain the enigmatic literal meaning of the torii's name ("bird perch").

Poles believed to have supported wooden bird figures very similar to the sotdae have been found together with wooden birds, and are believed by some historians to have somehow evolved into today's torii. Intriguingly, in both Korea and Japan single poles represent deities (kami in the case of Japan) and hashira (柱) is the counter for kami.

In Japan birds have also long had a connection with the dead, this may mean it was born in connection with some prehistorical funerary rite. Ancient Japanese texts like the Kojiki and the Nihon Shoki for example mention how Yamato Takeru after his death became a white bird and in that form chose a place for his own burial. For this reason, his mausoleum was then called shiratori misasagi (白鳥陵). Many later texts also show some relationship between dead souls and white birds, a link common also in other cultures, shamanic like the Japanese. Bird motifs from the Yayoi and Kofun periods associating birds with the dead have also been found in several archeological sites. This relationship between birds and death would also explain why, in spite of their name, no visible trace of birds remains in today's torii: birds were symbols of death, which in Shinto brings defilement (kegare).

Finally, the possibility that torii are a Japanese invention cannot be discounted. The first torii could have evolved already with their present function through the following sequence of events:

 * Four posts were placed at the corners of a sacred area and connected with a rope, thus dividing sacred and mundane.
 * Two taller posts were then placed at the center of the most auspicious direction, to let the priest in.
 * A rope was tied from one post to the other to mark the border between the outside and the inside, the sacred and the mundane. This hypothetical stage corresponds to a type of torii in actual use, the so-called shime-torii (注連鳥居), an example of which can be seen in front of Ōmiwa Shrine's haiden in Nara (see also the photo in the gallery).
 * The rope was replaced by a lintel.
 * Because the gate was structurally weak, it was reinforced with a tie-beam, and what is today called shinmei torii (神明鳥居) or futabashira torii (二柱鳥居) (see illustration at right) was born. This theory however does nothing to explain how the gates got their name.

The shinmei torii, whose structure agrees with the historians' reconstruction, consists of just four unbarked and unpainted logs: two vertical pillars (hashira (柱)) topped by a horizontal lintel (kasagi (笠木)) and kept together by a tie-beam (nuki (貫)). The pillars may have a slight inward inclination called uchikorobi (内転び) or just korobi (転び). Its parts are always straight.

Parts and ornamentations

 * Torii may be unpainted or painted vermilion and black. The color black is limited to the kasagi and the nemaki (根巻). Very rarely torii can be found also in other colors. Kamakura's Kamakura-gū for example has a white and red one.
 * The kasagi may be reinforced underneath by a second horizontal lintel called shimaki or shimagi (島木).
 * Kasagi and the shimaki may have an upward curve called sorimashi (反り増し).
 * The nuki is often held in place by wedges (kusabi (楔)). The kusabi in many cases are purely ornamental.
 * At the center of the nuki there may be a supporting strut called gakuzuka (額束), sometimes covered by a tablet carrying the name of the shrine (see photo in the gallery).
 * The pillars often rest on a white stone ring called kamebara (亀腹) or daiishi (台石). The stone is sometimes replaced by a decorative black sleeve called nemaki (根巻).
 * At the top of the pillars there may be a decorative ring called daiwa (台輪).
 * The gate has a purely symbolic function and therefore there usually are no doors or board fences, but exceptions exist, as for example in the case of Ōmiwa Shrine's triple-arched torii (miwa torii, see below).

Styles
Structurally, the simplest is the shime torii or chūren torii (注連鳥居) (see illustration below). Probably one of the oldest types of torii, it consists of two posts with a sacred rope called shimenawa tied between them.

All other torii can be divided in two families, the shinmei family (神明系) and the myōjin family (明神系). Torii of the first have only straight parts, the second have both straight and curved parts.

Shinmei family
The shinmei torii and its variants are characterized by straight upper lintels.

Shinmei torii
The shinmei torii (神明鳥居), which gives the name to the family, is constituted solely by a lintel (kasagi) and two pillars (hashira) united by a tie beam (nuki). In its simplest form, all four elements are rounded and the pillars have no inclination. When the nuki is rectangular in section, it is called Yasukuni torii, from Tokyo's Yasukuni Jinja. It is believed to be the oldest torii style.

Ise torii
伊勢鳥居 (Ise torii) (see illustration above) are gates found only at the Inner Shrine and Outer Shrine at Ise Shrine in Mie Prefecture. For this reason, they are also called Jingū torii, from Jingū, Ise Grand Shrine's official Japanese name.

There are two variants. The most common is extremely similar to a shinmei torii, its pillars however have a slight inward inclination and its nuki is kept in place by wedges (kusabi). The kasagi is pentagonal in section (see illustration in the gallery below). The ends of the kasagi are slightly thicker, giving the impression of an upward slant. All these torii were built after the 14th century.

The second type is similar to the first, but has also a secondary, rectangular lintel (shimaki) under the pentagonal kasagi.

This and the shinmei torii style started becoming more popular during the early 20th century at the time of State Shinto because they were considered the oldest and most prestigious.

Kasuga torii
The Kasuga torii (春日鳥居) is a myōjin torii (see illustration above) with straight top lintels. The style takes its name from Kasuga-taisha's ichi-no-torii (一の鳥居), or main torii.

The pillars have an inclination and are slightly tapered. The nuki protrudes and is held in place by kusabi driven in on both sides.

This torii was the first to be painted vermilion and to adopt a shimaki at Kasuga Taisha, the shrine from which it takes its name.

Hachiman torii
Almost identical to a kasuga torii (see illustration above), but with the two upper lintels at a slant, the Hachiman torii (八幡鳥居) first appeared during the Heian period. The name comes from the fact that this type of torii is often used at Hachiman shrines.

Kashima torii
The kashima torii (鹿島鳥居) (see illustration above) is a shinmei torii without korobi, with kusabi and a protruding nuki. It takes its name from Kashima Shrine in Ibaraki Prefecture.

Kuroki torii
The kuroki torii (黒木鳥居) is a shinmei torii built with unbarked wood. Because this type of torii requires replacement at three years intervals, it is becoming rare. The most notorious example is Nonomiya Shrine in Kyoto. The shrine now however uses a torii made of synthetic material which simulates the look of wood.

Shiromaruta torii
The shiromaruta torii (白丸太鳥居) or shiroki torii (白木鳥居) is a shinmei torii made with logs from which bark has been removed. This type of torii is present at the tombs of all Emperors of Japan.

Mihashira torii
The mihashira torii or Mitsubashira Torii (三柱鳥居) (see illustration above) is a type of torii which appears to be formed from three individual torii (see gallery). It is thought by some to have been built by early Japanese Christians to represent the Holy Trinity.

Myōjin family
The Myōjin torii and its variants are characterized by curved lintels.

Myōjin torii
The myōjin torii (明神鳥居), by far the most common torii style, are characterized by curved upper lintels (kasagi and shimaki). Both curve slightly upwards. Kusabi are present. A myōjin torii can be made of wood, stone, concrete or other materials and be vermilion or unpainted.

Nakayama torii
The Nakayama torii (中山鳥居) style, which takes its name from Nakayama Jinja in Okayama Prefecture, is basically a myōjin torii, but the nuki does not protrude from the pillars and the curve made by the two top lintels is more accentuated than usual. The torii at Nakayama Shrine that gives the style its name is 9 m tall and was erected in 1791.

Daiwa / Inari torii
The daiwa or Inari torii (大輪鳥居・稲荷鳥居) (see illustration above) is a myōjin torii with two rings called daiwa at the top of the two pillars. The name "Inari torii" comes from the fact that vermilion daiwa torii tend to be common at Inari shrines, but even at the famous Fushimi Inari Shrine not all torii are in this style. This style first appeared during the late Heian period.

Sannō torii
The sannō torii (山王鳥居) (see photo below) is myōjin torii with a gable over the two top lintels. The best example of this style is found at Hiyoshi Shrine near Lake Biwa.

Miwa torii
Also called sankō torii (三光鳥居), mitsutorii (三鳥居) or komochi torii (子持ち鳥居) (see illustration above), the miwa torii (三輪鳥居) is composed of three myōjin torii without inclination of the pillars. It can be found with or without doors. The most famous one is at Ōmiwa Shrine, in Nara, from which it takes its name.

Ryōbu torii
Also called yotsuashi torii (四脚鳥居), gongen torii (権現鳥居) or chigobashira torii (稚児柱鳥居), the ryōbu torii (両部鳥居) is a daiwa torii whose pillars are reinforced on both sides by square posts (see illustration above). The name derives from its long association with Ryōbu Shintō, a current of thought within Shingon Buddhism. The famous torii rising from the water at Itsukushima is a ryōbu torii, and the shrine used to be also a Shingon Buddhist temple, so much so that it still has a pagoda.

Hizen torii
The hizen torii (肥前鳥居) is an unusual type of torii with a rounded kasagi and pillars that flare downwards. They are found only in Saga prefecture and the neighboring areas.

title: Torii