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🔗 Philately

Letterlocking is the act of folding and securing a written message which could be on papyrus, parchment, or paper, so that it does not require an envelope or additional enclosure. It is a document security tradition which utilizes folding and cutting. The process dates to the 13th century in Western history, corresponding with the availability of flexible writing paper. Letterlocking uses small slits, tab, and holes placed directly into a letter, which combined with folding techniques are used to secure the letter ("letterpacket"), preventing reading the letter without breaking seals or slips, providing a means of tamper resistance. These folds and holes may be additionally secured with string and sealing wax. A Scottish diplomat in Italy, William Keith of Delny, sent letters to James VI of Scotland which would tear in two if not opened with care.

Intricate letterlocking works contain artistic elements, demonstrating more than a utilitarian purpose. While the use of sealing techniques may have been limited to ecclesiastic and the nobility, letterlocking was historically performed by all classes of writers. An individual could also be recognised by their personal technique of folding, as was the case with Jane Whorwood, of whose letter Charles I, imprisoned in Carisbrooke Castle on the Isle of Wight, wrote: "This Note [...] I know, by the fowldings [...] that it is written by [Mrs Whorwood]".

Letterlocking is also a discipline focusing on "the materially engineered security and privacy of letters, both as a technology and a historically evolving tradition."

🔗 Biography

Jonathan Gillette, known by the pseudonym why the lucky stiff (often abbreviated as _why), is a writer, cartoonist, artist, and programmer notable for his work with the Ruby programming language. Annie Lowrey described him as "one of the most unusual, and beloved, computer programmers" in the world. Along with Yukihiro Matsumoto and David Heinemeier Hansson, he was seen as one of the key figures in the Ruby community.

_why made a presentation enigmatically titled "A Starry Afternoon, a Sinking Symphony, and the Polo Champ Who Gave It All Up for No Reason Whatsoever" at the 2005 O'Reilly Open Source Convention. It explored how to teach programming and make the subject more appealing to adolescents. _why gave a presentation and performed with his band, the Thirsty Cups, at RailsConf in 2006.

On 19 August 2009, _why's accounts on Twitter and GitHub and his personally maintained websites went offline. Shortly before he disappeared, why the lucky stiff tweeted, "programming is rather thankless. u see your works become replaced by superior ones in a year. unable to run at all in a few more."

_why's colleagues have assembled collections of his writings and projects.

Later his website briefly went back online with a detailed explanation of his plans for the future.

🔗 Philosophy 🔗 Philosophy/Logic 🔗 Philosophy/Epistemology

The theory of belief functions, also referred to as evidence theory or Dempster–Shafer theory (DST), is a general framework for reasoning with uncertainty, with understood connections to other frameworks such as probability, possibility and imprecise probability theories. First introduced by Arthur P. Dempster in the context of statistical inference, the theory was later developed by Glenn Shafer into a general framework for modeling epistemic uncertainty—a mathematical theory of evidence. The theory allows one to combine evidence from different sources and arrive at a degree of belief (represented by a mathematical object called belief function) that takes into account all the available evidence.

In a narrow sense, the term Dempster–Shafer theory refers to the original conception of the theory by Dempster and Shafer. However, it is more common to use the term in the wider sense of the same general approach, as adapted to specific kinds of situations. In particular, many authors have proposed different rules for combining evidence, often with a view to handling conflicts in evidence better. The early contributions have also been the starting points of many important developments, including the transferable belief model and the theory of hints.

🔗 Architecture 🔗 Pennsylvania 🔗 Pittsburgh

A Pittsburgh toilet, or Pittsburgh potty, is a common fixture in pre-World War II houses built in Pittsburgh, Pennsylvania, United States and surrounding region. It consists of an ordinary flush toilet installed in the basement, with no surrounding walls. Most of these toilets are paired with a crude basement shower apparatus and large sink, which often doubles as a laundry basin. Also, because western Pennsylvania is a steep topographical zone, many basements have their own entryway, allowing homeowners to enter from their yard or garage, cleanse themselves in their basement, and then ascend their basement stairs refreshed. Its primary function was to serve as a cleanup station for steel mill workers to clean themselves after returning from work. The toilet fixtures would also limit the harm of sewage backups in hilly Pittsburgh, providing a lower, flushable outlet than the main part of the house.

🔗 United States 🔗 Library of Congress 🔗 Geography 🔗 Maps 🔗 Libraries

The Waldseemüller map or Universalis Cosmographia ("Universal Cosmography") is a printed wall map of the world by German cartographer Martin Waldseemüller, originally published in April 1507. It is known as the first map to use the name "America". The name America is placed on what is now called South America on the main map. As explained in Cosmographiae Introductio, the name was bestowed in honor of the Italian Amerigo Vespucci.

The map is drafted on a modification of Ptolemy's second projection, expanded to accommodate the Americas and the high latitudes. A single copy of the map survives, presently housed at the Library of Congress in Washington, D.C.

Waldseemüller also created globe gores, printed maps designed to be cut out and pasted onto spheres to form globes of the Earth. The wall map, and his globe gores of the same date, depict the American continents in two pieces. These depictions differ from the small inset map in the top border of the wall map, which shows the two American continents joined by an isthmus.

🔗 Mathematics

An untouchable number is a positive integer that cannot be expressed as the sum of all the proper divisors of any positive integer (including the untouchable number itself). That is, these numbers are not in the image of the aliquot sum function. Their study goes back at least to Abu Mansur al-Baghdadi (circa 1000 AD), who observed that both 2 and 5 are untouchable.

🔗 Science Fiction 🔗 Plants

A Dyson tree is a hypothetical genetically engineered plant (perhaps resembling a tree) capable of growing inside a comet, suggested by the physicist Freeman Dyson. Plants could produce a breathable atmosphere within hollow spaces in the comet (or even within the plants themselves), utilising solar energy for photosynthesis and cometary materials for nutrients, thus providing self-sustaining habitats for humanity in the outer solar system analogous to a greenhouse in space or a shell grown by a mollusc.

A Dyson tree might consist of a few main trunk structures growing out from a comet nucleus, branching into limbs and foliage that intertwine, forming a spherical structure possibly dozens of kilometers across.

The East German balloon escape occurred on 16 September 1979, when eight people in two families escaped the Eastern Bloc country of East Germany by crossing the border to the Western Bloc's West Germany in a homemade hot air balloon at around 2:00 a.m. The escape plot was carried out over one and a half years, including a previously unsuccessful attempt, three different balloons, and various modifications. One failed crossing alerted the government to the plot, but the police were not able to identify the suspects before their flight to the West.

🔗 Environment 🔗 Economics

Small Is Beautiful: A Study of Economics As If People Mattered is a collection of essays by German-born British economist E. F. Schumacher. The phrase "Small Is Beautiful" came from a principle espoused by Schumacher's teacher Leopold Kohr (1937-1994) The concept is often used to champion small, appropriate technologies or polities that are believed to empower people more, in contrast with phrases such as "bigger is better".

First published in 1973, Small Is Beautiful brought Schumacher's critiques of Western economics to a wider audience during the 1973 energy crisis and the popularisation of the concept of globalization. In 1995 The Times Literary Supplement ranked Small Is Beautiful among the 100 most influential books published since World War II. A further edition with commentaries was published in 1999.

🔗 Linguistics 🔗 Antarctica 🔗 Languages 🔗 English Language

Antarctic English is a variety of the English language spoken by people living on the continent of Antarctica and within the subantarctic islands.^: vii Spoken primarily by scientists and workers in the Antarctic tourism industry, it consists of various unique words and is spoken with a unique accent. During the 19th and 20th centuries, Antarctic English was influenced by Spanish-speaking South Americans and Northern European explorers who introduced new words that continue to be used today.