Have a deep view into what people are curious about.

🔗 Horticulture and Gardening 🔗 Occupations

Garden hermits or ornamental hermits were hermits encouraged to live in purpose-built hermitages, follies, grottoes, or rockeries on the estates of wealthy landowners, primarily during the 18th century. Such hermits would be encouraged to dress like druids and remain permanently on site, where they could be fed, cared for, and consulted for advice, or viewed for entertainment.

🔗 Technology 🔗 Sweden 🔗 Metalworking

Gauge blocks (also known as gage blocks, Johansson gauges, slip gauges, or Jo blocks) are a system for producing precision lengths. The individual gauge block is a metal or ceramic block that has been precision ground and lapped to a specific thickness. Gauge blocks come in sets of blocks with a range of standard lengths. In use, the blocks are stacked to make up a desired length.

An important feature of gauge blocks is that they can be joined together with very little dimensional uncertainty. The blocks are joined by a sliding process called wringing, which causes their ultra-flat surfaces to cling together. A small number of gauge blocks can be used to create accurate lengths within a wide range. By using 3 blocks at a time taken from a set of 30 blocks, one may create any of the 1000 lengths from 3.000 to 3.999 mm in 0.001 mm steps (or .3000 to .3999 inches in 0.0001 inch steps). Gauge blocks were invented in 1896 by Swedish machinist Carl Edvard Johansson. They are used as a reference for the calibration of measuring equipment used in machine shops, such as micrometers, sine bars, calipers, and dial indicators (when used in an inspection role). Gauge blocks are the main means of length standardization used by industry.

🔗 Biology 🔗 Astronomy 🔗 Color 🔗 Evolutionary biology

The Purple Earth Hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin-based chlorophyll, making the surface biosphere appear purplish rather than its current greenish color. It is estimated to have occurred between 3.5 and 2.4 billion years ago during the Archean eon, prior to the Great Oxygenation Event and Huronian glaciation.

Retinal-containing cell membranes exhibit a single light absorption peak centered in the energy-rich green-yellow region of the visible spectrum, but transmit and reflect red and blue light, resulting in a magenta color. Chlorophyll pigments, in contrast, absorb red and blue light, but little or no green light, which results in the characteristic green reflection of plants, green algae, cyanobacteria and other organisms with chlorophyllic organelles. The simplicity of retinal pigments in comparison to the more complex chlorophyll, their association with isoprenoid lipids in the cell membrane, as well as the discovery of archaeal membrane components in ancient sediments on the Early Earth are consistent with an early appearance of life forms with purple membranes prior to the turquoise of the Canfield ocean and later green photosynthetic organisms.

🔗 Ships

CS Alert, or HMTS Alert, was a cable-laying ship that had a significant role in World War I. She was launched in 1871 for the Submarine Telegraph Company with the name The Lady Carmichael. In 1890 the ship was acquired by the General Post Office (GPO) as part of the nationalisation of the British telegraph network. At the outbreak of World War I, Alert was immediately dispatched to cut German telegraph cables in the English Channel, seriously damaging Germany's ability to securely communicate with the rest of the world. Alert was taken out of service as a cable ship in 1915 but her cable-handling gear was retained for fitting on her replacement. After the war, she worked as a merchant ship under various names, finally being wrecked at Redcar under the name Norham in 1932.

🔗 Typography

Tiresias is a family of TrueType sans-serif typefaces that were designed with the aim of legibility by people with impaired vision at the Scientific Research Unit of Royal National Institute of Blind People in London. The font was originally designed for the RNIB by Chris Sharville of Laker Sharville Design Associates who was working with John Gill at the time.

The family includes

• Tiresias Infofont – for information labels, optimized for maximum legibility at a distance of 30–100 cm.
• Tiresias Keyfont – for labeling the tops of keys of keyboards, PIN pads, appliances, remote controls (features exaggerated punctuation marks, no descender on the J)
• Tiresias LPfont – for large-print publications. A wedge-serif design.
• Tiresias PCfont – for raster displays
• Tiresias Screenfont – for television subtitling and on-screen user interfaces
• Tiresias Signfont – a more open spacing for use on signs

In late 2007, all Tiresias fonts except Tiresias Screenfont were released under the GNU General Public License version 3 or any later version.

The Tiresias Screenfont was sold by Bitstream Inc., who in 2012 were acquired by Monotype Corporation. The acquiring company continues to market Tiresias on its websites.

🔗 Computing 🔗 Computer science 🔗 C/C++ 🔗 C/C++/C

In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the do-while loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program.

Loop unrolling attempts to reduce the overhead of conditional branching needed to check whether a loop is done, by executing a batch of loop bodies per iteration. To handle cases where the number of iterations is not divisible by the unrolled-loop increments, a common technique among assembly language programmers is to jump directly into the middle of the unrolled loop body to handle the remainder. Duff implemented this technique in C by using C's case label fall-through feature to jump into the unrolled body.

🔗 United States 🔗 Biography 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 United States/Military history - U.S. military history 🔗 Military history/Military biography 🔗 Biography/military biography 🔗 Military history/World War II 🔗 United States/Vermont

Ronald James Read (October 23, 1921 – June 2, 2014) was an American philanthropist, investor, janitor, and gas station attendant. Read grew up in Dummerston, Vermont, in an impoverished farming household. He walked or hitchhiked 4 mi (6.4 km) daily to his high school and was the first high school graduate in his family. He enlisted in the United States Army during World War II, serving in Italy as a military policeman. Upon an honorable discharge from the military in 1945, Read returned to Brattleboro, Vermont, where he worked as a gas station attendant and mechanic for about 25 years. Read retired for one year and then took a part-time janitor job at J. C. Penney where he worked for 17 years until 1997.

Read died in 2014. He received media coverage in numerous newspapers and magazines after bequeathing US$1.2 million to Brooks Memorial Library and $4.8 million to Brattleboro Memorial Hospital. Read amassed a fortune of almost $8 million by investing in dividend-producing stocks, avoiding the stocks of companies he did not understand such as technology companies, living frugally, and being a buy and hold investor in a diversified portfolio of stocks with a heavy concentration in blue chip companies.

Werckmeister temperaments are the tuning systems described by Andreas Werckmeister in his writings. The tuning systems are numbered in two different ways: the first refers to the order in which they were presented as "good temperaments" in Werckmeister's 1691 treatise, the second to their labelling on his monochord. The monochord labels start from III since just intonation is labelled I and quarter-comma meantone is labelled II. The temperament commonly known as "Werckmeister III" is referred to in this article as "Werckmeister I (III)".

The tunings I (III), II (IV) and III (V) were presented graphically by a cycle of fifths and a list of major thirds, giving the temperament of each in fractions of a comma. Werckmeister used the organbuilder's notation of ^ for a downwards tempered or narrowed interval and v for an upward tempered or widened one. (This appears counterintuitive - it is based on the use of a conical tuning tool which would reshape the ends of the pipes.) A pure fifth is simply a dash. Werckmeister was not explicit about whether the syntonic comma or Pythagorean comma was meant: the difference between them, the so-called schisma, is almost inaudible and he stated that it could be divided up among the fifths.

The last "Septenarius" tuning was not conceived in terms of fractions of a comma, despite some modern authors' attempts to approximate it by some such method. Instead, Werckmeister gave the string lengths on the monochord directly, and from that calculated how each fifth ought to be tempered.

🔗 Mathematics 🔗 Maps

The coastline paradox is the counterintuitive observation that the coastline of a landmass does not have a well-defined length. This results from the fractal curve-like properties of coastlines, i.e., the fact that a coastline typically has a fractal dimension (which in fact makes the notion of length inapplicable). The first recorded observation of this phenomenon was by Lewis Fry Richardson and it was expanded upon by Benoit Mandelbrot.

The measured length of the coastline depends on the method used to measure it and the degree of cartographic generalization. Since a landmass has features at all scales, from hundreds of kilometers in size to tiny fractions of a millimeter and below, there is no obvious size of the smallest feature that should be taken into consideration when measuring, and hence no single well-defined perimeter to the landmass. Various approximations exist when specific assumptions are made about minimum feature size.

The problem is fundamentally different from the measurement of other, simpler edges. It is possible, for example, to accurately measure the length of a straight, idealized metal bar by using a measurement device to determine that the length is less than a certain amount and greater than another amount—that is, to measure it within a certain degree of uncertainty. The more accurate the measurement device, the closer results will be to the true length of the edge. When measuring a coastline, however, the closer measurement does not result in an increase in accuracy—the measurement only increases in length; unlike with the metal bar, there is no way to obtain a maximum value for the length of the coastline.

In three-dimensional space, the coastline paradox is readily extended to the concept of fractal surfaces whereby the area of a surface varies, depending on the measurement resolution.

🔗 Aviation 🔗 Organized Labour

The Professional Air Traffic Controllers Organization or PATCO was a United States trade union that operated from 1968 until its decertification in 1981 following an illegal strike that was broken by the Reagan Administration. According to labor historian Joseph A. McCartin, the 1981 strike and defeat of PATCO was "one of the most important events in late twentieth century U.S. labor history".