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The '''Tetrahedral hypothesis''' is an [[Superseded scientific theories|obsolete scientific theory]] attempting to explain the arrangement of the [[Earth]]'s [[continent]]s and [[ocean]]s by referring to the geometry of a [[tetrahedron]]. Although it was a historically interesting theory in the late 19th and early 20th century, it was superseded by the concepts of [[continental drift]] and modern [[plate tectonics]]. | |||
==Theory== | |||
This idea, described as ‘"ingenious" by geologist [[Arthur Holmes]],<ref>{{cite book |author=[[Arthur Holmes]] |title=Principles of physical geology |url=http://books.google.com/books?id=XUJRAAAAMAAJ |year=1965 |publisher=Nelson |page=32 |isbn=0-17-448020-2}}</ref> is now of historical interest only, being finally refuted by that same Holmes.<ref>''Nature'' magazine, June 6th. 1925, p.873.</ref> It attempted to explain apparent anomalies in the distribution of land and water on the Earth's surface:<ref>{{cite book |author= A. Z. Bukhari |title=Encyclopedia of nature of geography |url=http://books.google.com/books?id=vef_5GExuUgC&pg=PA109 |year=2005 |publisher=Anmol Publications PVT. Limited |isbn=978-81-261-2443-5 |chapter= Continental Drift |pages=109–113 }}</ref> | |||
#More than 75% of the Earth's land area is in the [[northern hemisphere]]. | |||
#Continents are roughly triangular. | |||
#Oceans are roughly triangular. | |||
#The north pole is surrounded by water, the south pole by land. | |||
#Exactly opposite the Earth from land is almost always water. | |||
#The [[Pacific Ocean]] occupies about one third of the Earth's surface. | |||
To understand its appeal, consider the "regular solids": the [[sphere]] and the 5-member set of [[Platonic Solids]]. The solid with the lowest number of sides is the [[tetrahedron]] (four equilateral triangles); progressing through the [[cube]], and the [[icosahedron]] (20 sides), the sphere can be considered to have an infinite number of sides. All six regular solids share many symmetries. | |||
Now, for each regular solid, we may relate its surface area and volume by the equation: | |||
: <math>V = k\times A \times\sqrt{A}</math> | |||
where'' k'' is a characteristic of each solid, ''V'' its volume, and ''A'' its area. As we traverse the set in order of increasing number of faces, we find that k increases for each member; it is 0.0227 for a tetrahedron and 0.0940 for a sphere. Thus the tetrahedron is the regular solid with the largest surface area for a given volume, and makes a reasonable endpoint for a shrinking spherical Earth.<ref>{{cite book |title=Principles of Physical Geography |publisher=APH Publishing |year=2004 |isbn= 978-81-7648-731-3 |url=http://books.google.com/?id=TXkdMyGF_wgC&pg=PA84&lpg=PA84 |pages= 84–85 |author9=S. A. Qazi }}</ref> | |||
==History== | |||
[[Image:Tetrahedral hypothesis.jpg|thumb|alt=view of earth above Antarctica|Illustration of Tetrahedral hypothesis by [[William Lowthian Green]] from 1875]] | |||
The theory was first proposed by [[William Lowthian Green]] in 1875.<ref>{{cite book |title=Vestiges of the molten globe, as exhibited in the figure of the earth, volcanic action and physiography |author=[[William Lowthian Green]] |publisher= E. Stanford |place=London |year=1875 |oclc=3571917 |url= http://books.google.com/books?id=9DkDAAAAQAAJ }}</ref> | |||
It was still popular in 1917 when summarized as: | |||
<blockquote>"The law of least action … demands that the somewhat rigid crustal portion of the earth keep in contact with the lessening interior with the least possible readjustment of its surface. … a shrinking sphere tends by the law of least action to collapse into a tetrahedron, or a tetra-hedroid, a sphere marked by four equal and equidistant triangular projections; and the earth with its three about equal and equidistant double continental masses triangular southward with three intervening depressed oceans triangular northward, its northern ocean and southern continent, with land everywhere antipodal to water, realizes the tetrahedroid status remarkably.“<ref>{{cite news |title= Tetrahedral Deformations and Intercontinental Torsions |author = [[Benjamin Kendall Emerson]] |work= Proceedings, American Philosophical Society |volume= 56 |number= 6 |year= 1917 |url=http://books.google.com/books?id=4lULAAAAIAAJ&pg=PA445 |publisher=American Philosophical Society |isbn=978-1-4223-7253-1 |pages=445–472 }}</ref></blockquote> | |||
This is suggesting that a cooling spherical Earth might have shrunk to form a tetrahedron, with its vertices and edges forming the continents, and four oceans ([[Pacific Ocean]], [[Atlantic Ocean]], [[Indian Ocean]] and [[Arctic Ocean]]) on its faces. | |||
By 1915 German [[Alfred Wegener]] (1880–1930) had proposed in his [[continental drift]] theory that land masses moved great distances over the Earth's history. Wegener was also at first met with hostile reactions.<ref>{{cite web |title= Alfred Wegener (1880-1930) |url= http://www.ucmp.berkeley.edu/history/wegener.html |work= [[University of California Museum of Paleontology]] web site |publisher= University of California |year= 2006 |accessdate= August 4, 2010 }}</ref> | |||
By the mid-1920s the same Holmes developed theories on what could cause the drift.<ref>{{cite journal |title= The Origin of the Continents |author= [[Arthur Holmes]] |journal= Nature |date= June 6, 1925 |doi= 10.1038/115873a0 |pages= 873–874 |volume= 115 |issue=2901}}</ref><ref>{{cite journal |title= Theory of Continental Drift: a Symposium on the Origin and Movement of Land Masses, both Inter-Continental and Intra-Continental, as proposed by Alfred Wegener |author= [[Arthur Holmes]] |journal= Nature |date= September 22, 1928 |doi= 10.1038/122431a0 |pages= 431–433 |volume= 122 |issue=3073}}</ref> | |||
The [[plate tectonics]] theory is now generally accepted to explain the dynamic nature of the Earth's surface; the tetrahedral shape plays no special role in modern theories.<ref>{{cite web |title= Plate Tectonics: The Rocky History of an Idea |url= http://www.ucmp.berkeley.edu/geology/techist.html |work= [[University of California Museum of Paleontology]] web site |publisher= University of California |year= 2006 |accessdate= August 4, 2010 }}</ref> | |||
Explanations of details such as water to land ratios, the precise shape of continents and their sizes continue to be developed. | |||
==References== | |||
{{Reflist}} | |||
==Further reading== | |||
* {{cite book |title= The Tetrahedral Earth |work= The Book of Earths: Hollow Earth, Ancient Maps, Atlantis, and Other Theories |url= http://www.sacred-texts.com/earth/boe/boe34.htm |author= Edna Kenton |publisher= Forgotten Books|isbn= 978-1-60506-415-4 |accessdate= August 4, 2010 }} | |||
[[Category:Obsolete scientific theories]] | |||
[[Category:Plate tectonics]] | |||
Revision as of 23:11, 22 October 2013
The Tetrahedral hypothesis is an obsolete scientific theory attempting to explain the arrangement of the Earth's continents and oceans by referring to the geometry of a tetrahedron. Although it was a historically interesting theory in the late 19th and early 20th century, it was superseded by the concepts of continental drift and modern plate tectonics.
Theory
This idea, described as ‘"ingenious" by geologist Arthur Holmes,[1] is now of historical interest only, being finally refuted by that same Holmes.[2] It attempted to explain apparent anomalies in the distribution of land and water on the Earth's surface:[3]
- More than 75% of the Earth's land area is in the northern hemisphere.
- Continents are roughly triangular.
- Oceans are roughly triangular.
- The north pole is surrounded by water, the south pole by land.
- Exactly opposite the Earth from land is almost always water.
- The Pacific Ocean occupies about one third of the Earth's surface.
To understand its appeal, consider the "regular solids": the sphere and the 5-member set of Platonic Solids. The solid with the lowest number of sides is the tetrahedron (four equilateral triangles); progressing through the cube, and the icosahedron (20 sides), the sphere can be considered to have an infinite number of sides. All six regular solids share many symmetries.
Now, for each regular solid, we may relate its surface area and volume by the equation:
where k is a characteristic of each solid, V its volume, and A its area. As we traverse the set in order of increasing number of faces, we find that k increases for each member; it is 0.0227 for a tetrahedron and 0.0940 for a sphere. Thus the tetrahedron is the regular solid with the largest surface area for a given volume, and makes a reasonable endpoint for a shrinking spherical Earth.[4]
History
The theory was first proposed by William Lowthian Green in 1875.[5] It was still popular in 1917 when summarized as:
"The law of least action … demands that the somewhat rigid crustal portion of the earth keep in contact with the lessening interior with the least possible readjustment of its surface. … a shrinking sphere tends by the law of least action to collapse into a tetrahedron, or a tetra-hedroid, a sphere marked by four equal and equidistant triangular projections; and the earth with its three about equal and equidistant double continental masses triangular southward with three intervening depressed oceans triangular northward, its northern ocean and southern continent, with land everywhere antipodal to water, realizes the tetrahedroid status remarkably.“[6]
This is suggesting that a cooling spherical Earth might have shrunk to form a tetrahedron, with its vertices and edges forming the continents, and four oceans (Pacific Ocean, Atlantic Ocean, Indian Ocean and Arctic Ocean) on its faces.
By 1915 German Alfred Wegener (1880–1930) had proposed in his continental drift theory that land masses moved great distances over the Earth's history. Wegener was also at first met with hostile reactions.[7] By the mid-1920s the same Holmes developed theories on what could cause the drift.[8][9] The plate tectonics theory is now generally accepted to explain the dynamic nature of the Earth's surface; the tetrahedral shape plays no special role in modern theories.[10] Explanations of details such as water to land ratios, the precise shape of continents and their sizes continue to be developed.
References
43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.
Further reading
- 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
- ↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - ↑ Nature magazine, June 6th. 1925, p.873.
- ↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - ↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - ↑ 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - ↑ Template:Cite news
- ↑ Template:Cite web
- ↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting
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Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
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A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang - ↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting
In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang - ↑ Template:Cite web