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Harp

The harp is a stringed musical instrument that has individual strings running at an angle to its soundboard; the strings are plucked with the fingers. Harps can be made and played in various ways, standing or sitting, and in orchestras or concerts. Its most common form is triangular in shape and made of wood. Some have multiple rows of strings and pedal attachments.

Ancient depictions of harps were recorded in Mesopotamia (now Iraq), Persia (now Iran) and Egypt, and later in India and China. By medieval times harps had spread across Europe. Harps were found across the Americas where it was a popular folk tradition in some areas. Distinct designs also emerged from the African continent. Harps have symbolic political traditions and are often used in logos, including in Ireland.

Historically, strings were made of sinew (animal tendons). Other materials have included gut (animal intestines), plant fiber, braided hemp, cotton cord, silk, nylon, and wire.

History

Harps have been known since antiquity in Asia, Africa, and Europe, dating back at least as early as 3000 BCE. The instrument had great popularity in Europe during the Middle Ages and Renaissance, where it evolved into a wide range of variants with new technologies, and was disseminated to Europe's colonies, finding particular popularity in Latin America.

Although some ancient members of the harp family died out in the Near East and South Asia, descendants of early harps are still played in Myanmar and parts of Africa; other variants defunct in Europe and Asia have been used by folk musicians in the modern era.

West Asia and Egypt
The earliest harps and lyres were found in Sumer, 3500 BCE, and several harps were excavated from burial pits and royal tombs in Ur. The oldest depictions of harps without a forepillar can be seen in the wall paintings of ancient Egyptian tombs in the Nile Valley, which date from as early as 3000 BCE. These murals show an arched harp, an instrument that closely resembles the hunter's bow, without the pillar that we find in modern harps. The Chang flourished in Persia in many forms from its introduction, about 4000 BCE, until the 17th century.

Around 1900 BCE, arched harps in the Iraq-Iran region were replaced by angular harps with vertical or horizontal sound boxes.

By the start of the Common Era, "robust, vertical, angular harps", which had become predominant in the Hellenistic world, were cherished in the Sasanian court. In the last century of the Sasanian period, angular harps were redesigned to make them as light as possible ("light, vertical, angular harps"); while they became more elegant, they lost their structural rigidity. At the height of the Persian tradition of illustrated book production (1300–1600 CE), such light harps were still frequently depicted, although their use as musical instruments was reaching its end.

Greece

Marble sculptures of seated figures playing harps are known from the Cycladic civilization dating from 2800-2700 BC.

South Asia
Mesolithic era paintings from Bhimbetka show harp playing. An arched harp made of wooden brackets and metal strings is depicted on an Indus seal. The works of the Tamil Sangam literature describe the harp and its variants, as early as 200 BCE. Variants were described ranging from 14 to 17 strings, and the instrument used by wandering minstrels for accompaniment. Iconographic evidence of the yaal appears in temple statues dated as early as 600 BCE. One of the Sangam works, the Kallaadam recounts how the first yaaḻ harp was inspired by an archer's bow, when he heard the musical sound of its twang.

Another early South Asian harp was the ancient veena, not to be confused with the modern Indian veena which is a type of lute. Some Samudragupta gold coins show of the mid-4th century CE show (presumably) the king Samudragupta himself playing the instrument. The ancient veena survives today in Burma, in the form of the saung harp still played there.

East Asia
The harp was popular in ancient China and neighboring regions, though harps are largely extinct in East Asia in the modern day. The Chinese konghou harp is documented as early as the Spring and Autumn period (770–476 BCE), and became extinct during the Ming dynasty (1368–1644 CE). A similar harp, the Gonghu was played in ancient Korea, documented as early as the Goguryeo period (37 BCE – 686 CE).

Europe
While the angle and bow harps held popularity elsewhere, European harps favored the "pillar", a third structural member to support the far ends of the arch and soundbox. A harp with a triangular three-part frame is depicted on 8th-century Pictish stones in Scotland and in manuscripts (e.g. the Utrecht Psalter) from early 9th-century France. The curve of the harp's neck is a result of the proportional shortening of the basic triangular form to keep the strings equidistant; if the strings were proportionately distant they would be farther apart.

As European harps evolved to play more complex music, a key consideration was some way to facilitate the quick changing of a string's pitch to be able to play more chromatic notes. By the Baroque period in Italy and Spain, more strings were added to allow for chromatic notes in more complex harps. In Germany in the second half of the 17th century, diatonic single-row harps were fitted with manually turned hooks that fretted individual strings to raise their pitch by a half step. In the 18th century, a link mechanism was developed connecting these hooks with pedals, leading to the invention of the single-action pedal harp.

The first primitive form of pedal harps was developed in the Tyrol region of Austria. Jacob Hochbrucker was the next to design an improved pedal mechanism around 1720, followed in succession by Krumpholtz, Naderman, and the Erard company, who came up with the double mechanism, in which a second row of hooks was installed along the neck, capable of raising the pitch of a string by either one or two half steps. While one course of European harps led to greater complexity, resulting largely in the modern pedal harp, other harping traditions maintained simpler diatonic instruments which survived and evolved into modern traditions.

Americas
In the Americas, harps are widely but sparsely distributed, except in certain regions where the harp traditions are very strong. Such important centeres include Mexico, the Andean region, Venezuela, and Paraguay. They are derived from the Baroque harps that were brought from Spain during the colonial period. Detailed features vary from place to place. The Paraguayan harp is that country's national instrument, and has gained a worldwide reputation, with international influences alongside folk traditions. They have around 36 strings, are played with fingernails, and with a narrowing spacing and lower tension than modern Western harps, and have a wide and deep soundbox that tapers to the top.

The harp is also found in Argentina, though in Uruguay it was largely displaced in religious music by the organ by the end of the 18th century. The harp is historically found in Brazil, but mostly in the south of the country.

The Andean harp (Spanish/arpa), also known as the Peruvian harp, or indigenous harp, is widespread among peoples living in the highlands of the Andes: Quechua and Aymara, mainly in Peru, and also in Bolivia and Ecuador. It is relatively large, with a significantly increased volume of the resonator box, which gives basses a special richness. It usually accompanies love dances and songs, such as huayno. One of the most famous performers on the Andean harp was Juan Cayambe (Pimampiro Canton, Imbabura Province, Ecuador )

Mexican jarocha harp music of Veracruz has also gained some international recognition, evident in the popularity of "La Bamba". The arpa jarocha is typically played while standing. In southern Mexico (Chiapas), there is a very different indigenous style of harp music.

The harp arrived in Venezuela with Spanish colonists. There are two distinct traditions: the arpa llanera ('harp of the Llanos’, or plains) and the arpa central ('of the central area'). By the 2020s, three types of harps are typically found:
 * the traditional llanera harp, made of Cedar wood and has 32 strings, originally of the gut, but in modern times are of nylon. It is used to accompany both dancers and singers playing joropo music, a traditional form of Venezuelan music, also known as llanera music.
 * the arpa central (also known as arpa mirandina 'of Miranda State’, and arpa tuyera 'of the Tuy Valleys’) is strung with wire in the higher register.
 * the Venezuelan electric harp

Africa

A number of types of harps are found in Africa, predominantly not of the three-sided frame-harp type found in Europe. A number of these, referred to generically as African harps, are bow or angle harps, which lack forepillars joining the neck to the body.

A number of harp-like instruments in Africa are not easily classified with European categories. Instruments like the West African kora and Mauritanian ardin are sometimes labeled as "spike harp", "bridge harp", or harp lute since their construction includes a bridge which holds the strings laterally, vice vertically entering the soundboard.

Armenia
In Armenia, the harp has been used since the fourth century BC. Common usages included weddings and funerals. The "Antler Cup with a Feast Scene", found inside a vessel in Nor Aresh and now preserved in the Erebuni Fortress, depicts a harp. Information about early medieval Armenian musical instruments has been found in Armenian translations of the Bible. In the past, the harp was played in the royal residences, in the royal recreation rooms. Sometimes not only the royal musicians, but the kings themselves played the instrument. Of course, in the past, harps did not have the sound capabilities that they have today, but the fact that the Armenian people had the harp is a fact.

Armenians have had the instrument of harp since old times. This proves that Armenians loved the harp and used it in their everyday life, at weddings and burials. According to YSC professor, scholar of Middle Ages, doctor of Arts N. Tahmizyan many pagan musical instruments have kept their initial form and among them is the harp which was played not only at ceremonies. The instrument was performed by solo performers as well as with the accompaniment of other instruments. The Armenian translation of the Bible gives a lot of information about early medieval Armenian musical instruments. The translators of the Bible use the name harp among other quite popular musical instruments. In Armenian a verb has been formed from the name of the instrument: տաւղել which means to play the harp. The word has two meanings the second of which is stringed musical instrument which has the form of a triangular frame and this corresponds to the description of the musical instrument in Genesis 4:21 where it is stated. «Եւ նորա եղբօր անունը Յոբալ էր, որ բոլոր տավղահարների եւ սրնգահարների հայրն եղաւ»։ Other usages of the word can be found in one of the songs of 10th century Armenian medieval writer, founder of the Renaissance of the Armenian literature, cosmic monk Grigor Narekatsi. The song is called Song of Vardavar:

Քրքում վակասիր պտուղն սնանէր խուռն տերևով. Տերևն տաւիղ տուողին զոր երգէր Դաւիթ հրաշալին: (Տաղ Վարդավառի)

A proof of the instrument’s Armenian origin is the Horn Glass with the Scene of Feast picture which is kept in Erebuni museum: The glass was found in a big buried container in the district of Nor Aresh next to Erebuni castle in 1968 during construction works. The calf horn glass has peoples’ pictures on it. There are pictured a man and three women on it who obviously are participants of a feast. The third female musician is sitting on a chair with a harp in her hands. This find proves that the instrument in Armenia had its Armenian name in 4th century BC. N. Tahmizyan also writes about this horn glass in his book. This find is a proof that Armenians knew and even enjoyed playing the harp in 4th century BC.

On the famous Armenian Cilician silver glass a man is painted surrounded with his lively wife and animals.

Formerly the harp was played in royal castles. Sometimes not only musicians but also kings played the instrument. Of course, in the past harps did not have the sound range they have today but it is a fact that Armenians had the harp. Pictures of the harp can be found in People and Everyday Life (Yerevan, 1978) scientific work of Astghik Gevorgyan, a researcher at Matenadaran, the Mesrop Mashtots Institute of Ancient Manuscripts, Candidate in Arts. In her work pictures of the instrument can be found. In the first picture the man is playing the harp which is on his knees.

In the second picture the harp is played by a man who has a crown on his head from which we may conclude that the musician has a royal origin. This harp is bigger and leans on the floor. Not only did Armenians play the instrument but also they created songs about it. Kh. Avetisyan and V. Harutyunyan wrote a song called My Sweet Harp which was quite popular

This analysis and researches with the historical and archaeological proofs led us to the colnclusion that the instrument of harp existed and was widely used in Armenians’ everyday life including royal families. The instrument’s popularity has grown during the years and the harp has become an instrument that represents the emotional inner world of the Armenians.

South Asia
In India, the Bin-Baia harp survives about the Padhar people of Madhya Pradesh. The Kafir harp has been part of Nuristani musical tradition for many years.

East Asia
The harp largely became extinct in East Asia by the 17th century; around the year 1000, harps like the vajra began to replace prior harps. A few examples survived to the modern era, particularly Myanmar's saung-gauk, which is considered the national instrument in that country. Though the ancient Chinese konghou has not been directly resurrected, the name has been revived and applied to a modern newly invented instrument based on the Western classical harp, but with the strings doubled back to form two notes per string, allowing advanced techniques such as note-bending.

Concert harp
The concert harp is a technologically advanced instrument, particularly distinguished by its use of pedals, foot-controlled levers which can alter the pitch of given strings, making it chromatic and thus able to play a wide body of classical repertoire. The pedal harp contains seven pedals that each affect the tuning of all strings of one pitch-class. The pedals, from left to right, are D, C, B on the left side and E, F, G, A on the right. Pedals were first introduced in 1697 by Jakob Hochbrucker of Bavaria. In 1811 these were upgraded to the "double action" pedal system patented by Sébastien Erard.

The addition of pedals broadened the harp's abilities, allowing its gradual entry into the classical orchestra, largely beginning in the 19th century. The harp played little or no role in early classical music (being used only a handful of times by major composers such as Mozart and Beethoven), and its usage by Cesar Franck in his Symphony in D minor (1888) was described as "revolutionary" despite some body of prior classical usage. In the 20th century, the pedal harp found use outside of classical music, entering musical comedy films in 1929 with Arthur "Harpo" Marx, jazz with Casper Reardon in 1934, the Beatles 1967 single "She's Leaving Home", and several works by Björk which featured harpist Zeena Parkins. In the early 1980s, Swiss harpist Andreas Vollenweider exposed the concert harp to large new audiences with his popular new age/jazz albums and concert performances.

Folk, lever, and Celtic instruments
In the modern era, there is a family of mid-size harps, generally with nylon strings, and optionally with partial or full levers but without pedals. They range from two to six octaves, and are plucked with the fingers using a similar technique to the pedal harp. Though these harps evoke ties to historical European harps, their specifics are modern, and they are frequently referred to broadly as "Celtic harps" due to their region of revival and popular association, or more generically as "folk harps" due to their use in non-classical music, or as "lever harps" to contrast their modifying mechanism with the larger pedal harp.

The modern Celtic harp began to appear in the early 19th century in Ireland, contemporary with the dying-out of earlier forms of Gaelic harp. Dublin pedal harp maker John Egan developed a new type of harp which had gut strings and semitone mechanisms like an orchestral pedal harp; it was small and curved like the historical cláirseach or Irish harp, but its strings were of gut and the soundbox was much lighter. In the 1890s a similar new harp was also developed in Scotland as part of a Gaelic cultural revival. In the mid-20th century Jord Cochevelou developed a variant of the modern Celtic harp which he referred to as the "Breton Celtic harp"; his son Alan Stivell was to become the most influential Breton harper, and a strong influence in the broader world of the Celtic harp.

Multi-course harps
A multi-course harp is a harp with more than one row of strings, as opposed to the more common "single course" harp. On a double-harp, the two rows generally run parallel to each other, one on either side of the neck, and are usually both diatonic (sometimes with levers) with identical notes.

The triple harp originated in Italy in the 16th century, and arrived in Wales in the late 17th century where it established itself in the local tradition as the Welsh harp (telyn deires, "three-row harp"). The triple consists of two outer rows of identical diatonic strings with a third set of chromatic strings between them. These strings are off set to permit the harpist to reach past the outer row and pluck an inner string if a chromatic note is needed.

Chromatic-strung harps
Some harps, rather than using pedal or lever devices, achieve chromaticity by simply adding additional strings to cover the notes outside their diatonic home scale. The Welsh triple harp is one such instrument, and two other instruments employing this technique are the cross-strung harp and the inline chromatic harp.

The cross-strung harp has one row of diatonic strings, and a separate row of chromatic notes, angled in an "X" shape so that the row which can be played by the right hand at the top may be played by the left hand at the bottom, and vice versa. This variant was first attested as the arpa de dos órdenes ("two-row harp") in Spain and Portugal, in the 17th century.

The inline chromatic harp is generally a single-course harp with all 12 notes of the chromatic scale appearing in a single row. Single course inline chromatic harps have been produced at least since 1902, when Karl Weigel of Hanover patented a model of inline chromatic harp.

Electric harps
Amplified (electro-acoustic) hollow body and solid body electric lever harps are produced by many harp makers, including Lyon & Healy, Salvi, and Camac. They generally use individual piezo-electric sensors for each string, often in combination with small internal microphones to produce a mixed electrical signal. Hollow body instruments can also be played acoustically, while solid body instruments must be amplified.

The late-20th century Gravikord is a modern purpose-built electric double harp made of stainless steel based on the traditional West African kora.

Variations
Harps vary globally in many ways. In terms of size, many smaller harps can be played on the lap, whereas larger harps are quite heavy and rest on the floor. Different harps may use strings of catgut, nylon, metal, or some combination.

All harps have a neck, resonator, and strings, frame harps or triangular harps have a pillar at their long end to support the strings, while open harps, such as arch harps and bow harps, do not.

Modern harps also vary in techniques used to extend the range and chromaticism of the strings (e.g., adding sharps and flats). On lever harps one adjusts a string's note mid-performance by flipping a lever, which shortens the string enough to raise the pitch by a chromatic sharp. On pedal harps depressing the pedal one step turns geared levers on the strings for all octaves of a single pitch; most allow a second step that turns a second set of levers. The pedal harp is a standard instrument in the orchestra of the Romantic music era (ca. 1800–1910 CE) and the 20th and 21st century music era.

Structure and mechanism

Harps are essentially triangular and made primarily of wood. Strings are made of gut or wire, often replaced in the modern day by nylon or metal. The top end of each string is secured on the crossbar or neck, where each will have a tuning peg or similar device to adjust the pitch. From the crossbar, the string runs down to the sounding board on the resonating body, where it is secured with a knot; on modern harps the string's hole is protected with an eyelet to limit wear on the wood. The distance between the tuning peg and the soundboard, as well as tension and weight of the string, determine the pitch of the string. The body is hollow, and when a taut string is plucked, the body resonates, projecting sound.

The longest side of the harp is called the column or pillar (though some earlier harps, such as a "bow harp", lack a pillar). On most harps the sole purpose of the pillar is to hold up the neck against the great strain of the strings. On harps which have pedals (largely the modern concert harp), the pillar is a hollow column and encloses the rods which adjust the pitches, which are levered by pressing pedals at the base of the instrument.

On harps of earlier design, a single string produces only a single pitch unless it is retuned. In many cases this means such a harp can only play in one key at a time and must be retuned to play in another key. Harpers and luthiers have developed various remedies to this limitation: These solutions increase the versatility of a harp at the cost of adding complexity, weight, and expense.
 * the addition of extra strings to cover chromatic notes (sometimes in separate or angled rows distinct from the main row of strings),
 * addition of small levers on the crossbar which when actuated raise the pitch of a string by a set interval (usually a semitone), or
 * use of pedals at the base of the instrument, pressed with the foot, which move additional small pegs on the crossbar. The small pegs gently contact the string near the tuning peg, changing the vibrating length, but not the tension, and hence the pitch of the string.

Terminology and etymology
The modern English word harp comes from the Old English hearpe; akin to Old High German harpha. A person who plays a pedal harp is called a "harpist"; a person who plays a folk-harp is called a "harper" or sometimes a "harpist"; either may be called a "harp-player", and the distinctions are not strict.

A number of instruments that are not harps are none-the-less colloquially referred to as "harps". Chordophones like the aeolian harp (wind harp), the autoharp, the psaltery, as well as the piano and harpsichord, are not harps, but zithers, because their strings are parallel to their soundboard. Harps' strings rise approximately perpendicularly from the soundboard. Similarly, the many varieties of harp guitar and harp lute, while chordophones, belong to the lute family and are not true harps. All forms of the lyre and kithara are also not harps, but belong to the fourth family of ancient instruments under the chordophones, the lyres, closely related to the zither family.

The term "harp" has also been applied to many instruments which are not even chordophones. The vibraphone was (and is still) sometimes referred to as the "vibraharp", though it has no strings and its sound is produced by striking metal bars. In blues music, the harmonica is often casually referred to as a "blues harp" or "harp", but it is a free reed wind instrument, not a stringed instrument, and is therefore not a true harp. The Jew's harp is neither Jewish nor a harp; it is a plucked idiophone and likewise not a stringed instrument. The laser harp is not a stringed instrument at all, but is a harp-shaped electronic instrument controller that has laser beams where harps have strings.

Ireland

The harp has been used as a political symbol of Ireland for centuries. Its origin is unknown but from the evidence of the ancient oral and written literature, it has been present in one form or another since at least the 6th century or before. According to tradition, Brian Boru, High King of Ireland (died at the Battle of Clontarf, 1014) played the harp, as did many of the gentry in the country during the period of the Gaelic Lordship of Ireland (ended c. 1607 with the Flight of the Earls following the Elizabethan Wars).

In traditional Gaelic society every clan and chief of any consequence would have a resident harp player who would compose eulogies and elegies (later known as "planxties") in honour of the leader and chief men of the clan. The harp was adopted as a symbol of the Kingdom of Ireland on the coinage from 1542, and in the Royal Standard of King James VI and I in 1603 and continued to feature on all English and United Kingdom Royal Standards ever since, though the styles of the harps depicted differed in some respects. It was also used on the Commonwealth Jack of Oliver Cromwell issued in 1649 and on the Protectorate Jack issued in 1658 as well as on the Lord Protector's Standard issued on the succession of Richard Cromwell in 1658. The harp is also traditionally used on the flag of Leinster.

Since 1922, the government of Ireland has used a similar left-facing harp, based on the Trinity College Harp in the Library of Trinity College Dublin as its state symbol. This design first appeared on the Great Seal of the Irish Free State, which in turn was replaced by the coat of arms, the Irish Presidential Standard and the Presidential Seal in the 1937 Constitution of Ireland. The harp emblem is used on official state seals and documents including the Irish passport and has appeared on Irish coinage from the Middle Ages to the current Irish imprints of euro coins.

Elsewhere
The South Asian Tamil harp yaal is the symbol of City of Jaffna, Sri Lanka, whose legendary root originates from a harp player.

The arms of the Finnish city of Kangasala features a red, eagle-headed harp.

Religious
In the context of Christianity, heaven is sometimes symbolically depicted as populated by angels playing harps, giving the instrument associations of the sacred and heavenly. In the Bible, Genesis 4:21 says that Jubal, the first musician and son of Lamech, was 'the father of all who play' the harp and flute.

Many depictions of King David in Jewish art have him holding or playing a harp, such as a sculpture outside King David's tomb in Jerusalem.

Corporate

The harp is also used extensively as a corporate logo, predominantly by companies that have, or wish to suggest, a connection with Ireland. The Irish brewer Guinness has used a right-facing harp (in contrast to the Irish State emblem's left-facing version) as its emblem since 1759, the Harp Lager brand has done so since 1960. The Irish Independent newspaper has used a harp in its masthead since 1961. The Irish airline Ryanair, founded in 1985, also features a stylised harp in its logo.

Other organisations in Ireland use the harp in their corporate identity, but not always prominently; these include the National University of Ireland and the associated University College Dublin, and the Gaelic Athletic Association. In Northern Ireland, the Police Service of Northern Ireland and the Queen's University of Belfast use the harp as part of their identity.

Sporting
In sport, the harp is used in the emblems of the League of Ireland football team Finn Harps F.C., Donegal's senior soccer club. Outside of Ireland, it appears in the badge of the Scottish Premiership team Hibernian F.C. – a team originally founded by Irish emigrants.

Not all sporting uses of the harp are references to Ireland, however: the Iraqi football club Al-Shorta has used a harp as its emblem since the early 1990s, after they gained the nickname Al-Qithara ("the harp") when their style of play was likened to fine harp-playing by a television presenter.

Types of harp

 * Celtic harp, or Clàrsach, a modern replica of Medieval north European harps
 * Claviharp, a 19th century instrument that combined a harp with a keyboard
 * Epigonion, a 40 stringed instrument in ancient Greece thought to have been a harp
 * Kantele, a traditional Finnish and Karelian zither-like instrument
 * Konghou, name shared by an ancient Chinese harp and a modern re-adaption
 * Kora, a west-African folk-instrument, intermediate between a harp and a lute
 * Lyre, kithara, zither-like instruments used in Greek classical antiquity and later
 * Pedal harp, the modern, chromatic concert harp
 * Psaltery, a small, flat, lap instrument in the zither family
 * Triple harp, a chromatic multi-course harp traditional in Wales

title: Harp


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Hollow Earth

The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproven, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.

It was still occasionally defended through the mid-19th century, notably by John Cleves Symmes Jr. and J. N. Reynolds, but by this time it was part of popular pseudoscience and no longer a scientifically viable hypothesis.

The concept of a hollow Earth still recurs in folklore and as a premise for subterranean fiction, a subgenre of adventure fiction. Hollow Earth also recurs in conspiracy theories such as the underground kingdom of Agartha and the Cryptoterrestrial hypothesis and is often said to be inhabited by mythological figures or political leaders.

Ancient times
In ancient times, the concept of a subterranean land inside the Earth appeared in mythology, folklore and legends. The idea of subterranean realms seemed arguable, and became intertwined with the concept of "places" of origin or afterlife, such as the Greek underworld, the Nordic Svartálfaheimr, the Christian Hell, and the Jewish Sheol (with details describing inner Earth in Kabalistic literature, such as the Zohar and Hesed L'Avraham). The idea of a subterranean realm is also mentioned in Tibetan Buddhist belief. According to one story from Tibetan Buddhist tradition, there is an ancient city called Shamballa which is located inside the Earth.

According to the Ancient Greeks, there were caverns under the surface which were entrances leading to the underworld, some of which were the caverns at Tainaron in Lakonia, at Troezen in Argolis, at Ephya in Thesprotia, at Herakleia in Pontos, and in Ermioni. In Thracian and Dacian legends, it is said that there are caverns occupied by an ancient god called Zalmoxis. In Mesopotamian religion there is a story of a man who, after traveling through the darkness of a tunnel in the mountain of "Mashu", entered a subterranean garden.

In Celtic mythology there is a legend of a cave called "Cruachan", also known as "Ireland's gate to Hell", a mythical and ancient cave from which strange creatures would emerge and be seen on the surface of the Earth. There are also stories of medieval knights and saints who went on pilgrimages to a cave located in Station Island, County Donegal in Ireland, where they made journeys inside the Earth into a place of purgatory. In County Down, Northern Ireland there is a myth which says tunnels lead to the land of the subterranean Tuatha Dé Danann, a group of people who are believed to have introduced Druidism to Ireland, and then went back underground.

In Hindu mythology, the underworld is referred to as Patala. In the Bengali version of the Hindu epic Ramayana, it has been depicted how Rama and Lakshmana were taken by the king of the underworld Ahiravan, brother of the demon king Ravana. Later on they were rescued by Hanuman. The Angami Naga tribes of India claim that their ancestors emerged in ancient times from a subterranean land inside the Earth. The Taino from Cuba believe their ancestors emerged in ancient times from two caves in a mountain underground.

Natives of the Trobriand Islands believe that their ancestors had come from a subterranean land through a cavern hole called "Obukula". Mexican folklore also tells of a cave in a mountain five miles south of Ojinaga, and that Mexico is possessed by devilish creatures who came from inside the Earth.

In the Middle Ages, an ancient German myth held that some mountains located between Eisenach and Gotha hold a portal to the inner Earth. A Russian legend says the Samoyeds, an ancient Siberian tribe, traveled to a cavern city to live inside the Earth. The Italian writer Dante describes a hollow earth in his well-known 14th-century work Inferno, in which the fall of Lucifer from heaven caused an enormous funnel to appear in previously solid and spherical earth, as well as an enormous mountain opposite it, "Purgatory".

In Native American mythology, it is said that the ancestors of the Mandan people in ancient times emerged from a subterranean land through a cave on the north side of the Missouri River. There is also a tale about a tunnel in the San Carlos Apache Indian Reservation in Arizona near Cedar Creek which is said to lead inside the Earth to a land inhabited by a mysterious tribe. It is also the belief of the tribes of the Iroquois that their ancient ancestors emerged from a subterranean world inside the Earth. The elders of the Hopi people believe that a Sipapu entrance in the Grand Canyon exists which leads to the underworld.

Brazilian Indians, who live alongside the Parima River in Brazil, claim that their forefathers emerged in ancient times from an underground land, and that many of their ancestors still remained inside the Earth. Ancestors of the Inca supposedly came from caves which are located east of Cuzco, Peru.

16th to 18th centuries

The notion was proposed by Athanasius Kircher's non-fiction Mundus Subterraneus (1665), which speculated that there is an "intricate system of cavities and a channel of water connecting the poles".

Edmond Halley in 1692 conjectured that the Earth might consist of a hollow shell about 800 km thick, two inner concentric shells and an innermost core. Atmospheres separate these shells, and each shell has its own magnetic poles. The spheres rotate at different speeds. Halley proposed this scheme in order to explain anomalous compass readings. He envisaged the atmosphere inside as luminous (and possibly inhabited) and speculated that escaping gas caused the Aurora Borealis.

Le Clerc Milfort in 1781 led a journey with hundreds of Muscogee Peoples to a series of caverns near the Red River above the junction of the Mississippi River. According to Milfort the original Muscogee Peoples' ancestors are believed to have emerged out to the surface of the Earth in ancient times from the caverns. Milfort also claimed the caverns they saw "could easily contain 15,000 – 20,000 families".

It is often claimed that mathematician Leonhard Euler proposed a single-shell hollow Earth with a small sun (1,000 kilometres across) at the center, providing light and warmth for an inner-Earth civilization, but that is not true. Instead, he did a thought experiment of an object dropped into a hole drilled through the center, unrelated to a hollow Earth.

19th century
In 1818, John Cleves Symmes, Jr. suggested that the Earth consisted of a hollow shell about 1300 km thick, with openings about 2300 km across at both poles with 4 inner shells each open at the poles. Symmes became the most famous of the early Hollow Earth proponents, and Hamilton, Ohio even has a monument to him and his ideas. He proposed making an expedition to the North Pole hole, thanks to efforts of one of his followers, James McBride.

J. N. Reynolds also delivered lectures on the "Hollow Earth" and argued for an expedition. Reynolds went on an expedition to Antarctica himself but missed joining the Great U.S. Exploring Expedition of 1838–1842, even though that venture was a result of his agitation.

Though Symmes himself never wrote a book on the subject, several authors published works discussing his ideas. McBride wrote Symmes' Theory of Concentric Spheres in 1826. It appears that Reynolds has an article that appeared as a separate booklet in 1827: Remarks of Symmes' Theory Which Appeared in the American Quarterly Review. In 1868, professor W.F. Lyons published The Hollow Globe which put forth a Symmes-like Hollow Earth hypothesis, but failed to mention Symmes himself. Symmes's son Americus then published The Symmes' Theory of Concentric Spheres in 1878 to set the record straight.

Sir John Leslie proposed a hollow Earth in his 1829 Elements of Natural Philosophy (pp. 449–53).

In 1864, in Journey to the Center of the Earth Jules Verne describes an expedition into the Earth's interior via the fictional Icelandic volcano Scartaris. The protagonists do not actually reach the centre, but nevertheless discover a subterranean ocean inhabited by creatures believed extinct. They escape through another volcano on the Italian island of Stromboli.

William Fairfield Warren, in his book Paradise Found – The Cradle of the Human Race at the North Pole (1885), presented his belief that humanity originated on a continent in the Arctic called Hyperborea. This influenced some early Hollow Earth proponents. According to Marshall Gardner, both the Eskimo and Mongolian peoples had come from the interior of the Earth through an entrance at the North Pole.

20th century
NEQUA or The Problem of the Ages, first serialized in a newspaper printed in Topeka, Kansas in 1900 and considered an early feminist utopian novel, mentions John Cleves Symmes' theory to explain its setting in a hollow Earth.

An early 20th-century proponent of hollow Earth, William Reed, wrote Phantom of the Poles in 1906. He supported the idea of a hollow Earth, but without interior shells or the inner sun.

The spiritualist writer Walburga, Lady Paget in her book Colloquies with an unseen friend (1907) was an early writer to mention the hollow Earth hypothesis. She claimed that cities exist beneath a desert, which is where the people of Atlantis moved. She said an entrance to the subterranean kingdom will be discovered in the 21st century.

Marshall Gardner wrote A Journey to the Earth's Interior in 1913 and published an expanded edition in 1920. He placed an interior sun in the Earth and built a working model of the Hollow Earth which he patented. Gardner made no mention of Reed, but did criticize Symmes for his ideas. Around the same time, Vladimir Obruchev wrote a novel titled Plutonia, in which the Hollow Earth possessed an inner Sun and was inhabited by prehistoric species. The interior was connected with the surface by an opening in the Arctic.

The explorer Ferdynand Ossendowski wrote a book in 1922 titled Beasts, Men and Gods. Ossendowski said he was told about a subterranean kingdom that exists inside the Earth. It was known to Buddhists as Agharti.

George Papashvily in his Anything Can Happen (1940) claimed the discovery in the Caucasus mountains of a cavern containing human skeletons "with heads as big as bushel baskets" and an ancient tunnel leading to the center of the Earth. One man entered the tunnel and never returned.

Novelist Lobsang Rampa in his book The Cave of the Ancients said an underground chamber system exists beneath the Himalayas of Tibet, filled with ancient machinery, records and treasure. Michael Grumley, a cryptozoologist, has linked Bigfoot and other hominid cryptids to ancient tunnel systems underground.

According to the ancient astronaut writer Peter Kolosimo a robot was seen entering a tunnel below a monastery in Mongolia. Kolosimo also claimed a light was seen from underground in Azerbaijan. Kolosimo and other ancient astronaut writers such as Robert Charroux linked these activities to UFOs.

A book by "Dr. Raymond Bernard" which appeared in 1964, The Hollow Earth, exemplifies the idea of UFOs coming from inside the Earth, and adds the idea that the Ring Nebula proves the existence of hollow worlds, as well as speculation on the fate of Atlantis and the origin of flying saucers. An article by Martin Gardner revealed that Walter Siegmeister used the pseudonym "Bernard", but not until the 1989 publishing of Walter Kafton-Minkel's Subterranean Worlds: 100,000 Years of Dragons, Dwarfs, the Dead, Lost Races & UFOs from Inside the Earth did the full story of Bernard/Siegmeister become well-known.

The science fiction pulp magazine Amazing Stories promoted one such idea from 1945 to 1949 as "The Shaver Mystery". The magazine's editor, Ray Palmer, ran a series of stories by Richard Sharpe Shaver, claiming that a superior pre-historic race had built a honeycomb of caves in the Earth, and that their degenerate descendants, known as "Dero", live there still, using the fantastic machines abandoned by the ancient races to torment those of us living on the surface. As one characteristic of this torment, Shaver described "voices" that purportedly came from no explainable source. Thousands of readers wrote to affirm that they, too, had heard the fiendish voices from inside the Earth. The writer David Hatcher Childress authored Lost Continents and the Hollow Earth (1998) in which he reprinted the stories of Palmer and defended the Hollow Earth idea based on alleged tunnel systems beneath South America and Central Asia.

Hollow Earth proponents have claimed a number of different locations for the entrances which lead inside the Earth. Other than the North and South poles, entrances in locations which have been cited include: Paris in France, Staffordshire in England, Montreal in Canada, Hangzhou in China, and the Amazon rainforest.

Variations
In "A Culture of Conspiracy", Political scientist Michael Barkun draws a distinction between the terms hollow earth and inner earth, to differentiate materials that conceive the majority of the interior of the planet to be hollow, from those that view it as solid but honeycombed with interconnected spaces.

Concave Hollow Earths

Instead of saying that humans live on the exterior surface of a hollow planet, sometimes called a "convex" Hollow Earth hypothesis, it is hypothesized humans live on the interior surface. This has been called the "concave" Hollow Earth hypothesis or skycentrism.

Cyrus Teed, a doctor from upstate New York, proposed such a concave Hollow Earth in 1869, calling his scheme "Cellular Cosmogony". Teed founded a group called the Koreshan Unity based on this notion, which he called Koreshanity. The main colony survives as a preserved Florida state historic site, at Estero, Florida, but all of Teed's followers have now died. Teed's followers claimed to have experimentally verified the concavity of the Earth's curvature, through surveys of the Florida coastline making use of "rectilineator" equipment.

Several 20th-century German writers, including Peter Bender, Johannes Lang, Karl Neupert, and Fritz Braut, published works advocating the Hollow Earth hypothesis, or Hohlweltlehre. It has even been reported, although apparently without historical documentation, that Adolf Hitler was influenced by concave Hollow Earth ideas and sent an expedition in an unsuccessful attempt to spy on the British fleet by pointing infrared cameras up at the sky.

The Egyptian mathematician Mostafa Abdelkader wrote several scholarly papers working out a detailed mapping of the Concave Earth model. In his book On the Wild Side (1992), Martin Gardner discusses the Hollow Earth model articulated by Abdelkader. According to Gardner, this hypothesis posits that light rays travel in circular paths, and slow as they approach the center of the spherical star-filled cavern. No energy can reach the center of the cavern. A drill, Gardner says, would lengthen as it traveled away from the cavern and eventually pass through the "point at infinity" corresponding to the center of the Earth. Gardner notes that "most mathematicians believe that an inside-out universe, with properly adjusted physical laws, is empirically irrefutable". Gardner rejects the concave Hollow Earth hypothesis on the basis of Occam's razor.

Purportedly verifiable hypotheses of a Concave Hollow Earth need to be distinguished from a thought experiment which defines a coordinate transformation such that the interior of the Earth becomes "exterior" and the exterior becomes "interior". (For example, in spherical coordinates, let radius r go to R2/r where R is the Earth's radius; see inversive geometry.) The transformation entails corresponding changes to the forms of physical laws. This is not a hypothesis but an illustration of the fact that any description of the physical world can be equivalently expressed in more than one way.

Schiehallion experiment
In 1735, Pierre Bouguer and Charles Marie de La Condamine chartered an expedition from France to the Chimborazo volcano in Ecuador. Arriving and climbing the volcano in 1738, they conducted a vertical deflection experiment at two different altitudes to determine how local mass anomalies affected gravitational pull. In a paper written a little over ten years later, Bouguer commented that his results had at least falsified the Hollow Earth Theory. In 1772, Nevil Maskelyne proposed to repeat the same experiment to the Royal Society. Within the same year, the Committee of Attraction was formed and they sent Charles Mason to find the perfect candidate for the vertical deflection experiment. Mason found the Schiehallion mountain, where the experiment took place and not only supported the earlier Chimborazo Experiment but yielded far greater results.

Seismic
The picture of the structure of the Earth that has been arrived at through the study of seismic waves is quite different from a fully hollow Earth. The time it takes for seismic waves to travel through and around the Earth directly contradicts a fully hollow sphere. The evidence indicates the Earth is mostly filled with solid rock (mantle and crust), liquid nickel-iron alloy (outer core), and solid nickel-iron (inner core).

Gravity
Another set of scientific arguments against a Hollow Earth or any hollow planet comes from gravity. Massive objects tend to clump together gravitationally, creating non-hollow spherical objects such as stars and planets. The solid spheroid is the best way to minimize the gravitational potential energy of a rotating physical object; having hollowness is unfavorable in the energetic sense. In addition, ordinary matter is not strong enough to support a hollow shape of planetary size against the force of gravity; a planet-sized hollow shell with the known, observed thickness of the Earth's crust would not be able to achieve hydrostatic equilibrium with its own mass and would collapse.

Based upon the size of the Earth and the force of gravity on its surface, the average density of the planet Earth is 5.515 g/cm3, and typical densities of surface rocks are only half that (about 2.75 g/cm3). If any significant portion of the Earth were hollow, the average density would be much lower than that of surface rocks. The only way for Earth to have the force of gravity that it does is for much more dense material to make up a large part of the interior. Nickel-iron alloy under the conditions expected in a non-hollow Earth would have densities ranging from about 10 to 13 g/cm3, which brings the average density of Earth to its observed value.

Direct observation
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the Kola Superdeep Borehole, with a true vertical drill-depth of around 12 km. However, the distance to the center of the Earth is nearly 6400 km.

In fiction
The idea of a hollow Earth is a common element of fiction, appearing as early as Ludvig Holberg's 1741 novel Nicolai Klimii iter subterraneum («Niels Klim's Underground Travels»), in which Nicolai Klim falls through a cave while spelunking and spends several years living on a smaller globe both within and the inside of the outer shell.

Other notable early examples include Giacomo Casanova's 1788 Icosaméron, a 5-volume, 1,800-page story of a brother and sister who fall into the Earth and discover the subterranean utopia of the Mégamicres, a race of multicolored, hermaphroditic dwarves; Vril published anonymously in 1819; Symzonia: A Voyage of Discovery by a "Captain Adam Seaborn" (1820) which reflected the ideas of John Cleves Symmes, Jr.; Edgar Allan Poe's 1838 novel The Narrative of Arthur Gordon Pym of Nantucket; Jules Verne's 1864 novel Journey to the Center of the Earth, which showed a subterranean world teeming with prehistoric life; George Sand's 1864 novel Laura, Voyage dans le Cristal where giant crystals could be found in the interior of the Earth; Etidorhpa, an 1895 science-fiction allegory with major subterranean themes; and The Smoky God, a 1908 novel that included the idea that the North Pole was the entrance to the hollow planet.

In William Henry Hudson's 1887 romance, A Crystal Age, the protagonist falls down a hill into a Utopian paradise; since he falls into this world, it is sometimes classified as a hollow Earth story; although the hero himself thinks he may have traveled forward in time by millennia.

The idea was used by Edgar Rice Burroughs in the seven-novel "Pellucidar" series, beginning with At the Earth's Core (1914). Using a mechanical drill, called the Iron Mole, his heroes David Innes and Professor Abner Perry discover a prehistoric world called Pellucidar, 500 miles below the surface, that is lit by a constant noonday inner sun. They find prehistoric people, dinosaurs, prehistoric mammals and the Mahar, who evolved from pterosaurs. The series ran for six more books, ending with Savage Pellucidar (1963). The 1915 novel Plutonia by Vladimir Obruchev uses the concept of the Hollow Earth to take the reader through various geological epochs.

In recent decades, the idea has become a staple of the science fiction and adventure genres across films (Children Who Chase Lost Voices, Ice Age: Dawn of the Dinosaurs, Aquaman and the MonsterVerse), television programs (Inside Job, Slugterra, and the third and fourth seasons of Sanctuary), role-playing games (e.g., the Hollow World Campaign Set for Dungeons & Dragons, Hollow Earth Expedition), and video games (Torin's Passage and Gears of War). The idea is also partially used in the Marvel Comics universe, where there exists a subterranean realm beneath the Earth known as Subterranea. The Super Nintendo Entertainment System (SNES) video game Terranigma features this concept in the opening and closing acts of the game.

The Hollow Earth is a key location in Legendary Pictures's MonsterVerse franchise, being the point of origin of the Titans and the strange animals of Skull Island. Initially being teased in Kong: Skull Island and Godzilla: King of the Monsters, a full expedition into the Hollow Earth is a primary focus of Godzilla vs. Kong, its sequel Godzilla x Kong: The New Empire, and the Monarch: Legacy of Monsters TV series.

In popular art
In 1975, Japanese artist Tadanori Yokoo used elements of the Agartha legend, along with other Eastern subterranean myths, to depict an advanced civilization in the cover art for jazz musician Miles Davis's album Agharta. Tadanori said he was partly inspired by his reading of Raymond W. Bernard's 1969 book The Hollow Earth.

General and cited references

 * Kafton-Minkel, Walter. Subterranean Worlds. Loompanics Unlimited, 1989.
 * Lamprecht, Jan. Hollow Planets: A Feasibility Study of Possible Hollow Worlds Grave Distraction Publications, 2014.
 * Lewis, David. The Incredible Cities of Inner Earth. Science Research Publishing House, 1979.
 * Seaborn, Captain Adam. Symzonia; Voyage of Discovery. J. Seymour, 1820.
 * Standish, David. Hollow Earth: The Long and Curious History of Imagining Strange Lands, Fantastical Creatures, Advanced Civilizations, and Marvelous Machines Below the Earth's Surface. Da Capo Press, 2006.

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title: Hollow Earth