An hourglass (or sandglass, sand timer, sand clock or egg timer) is a device used to measure the passage of time. It comprises two glass bulbs connected vertically by a narrow neck that allows a regulated trickle of material (historically sand) from the upper bulb to the lower one. Factors affecting the time it measured include sand quantity, sand coarseness, bulb size, and neck width. Hourglasses may be reused indefinitely by inverting the bulbs once the upper bulb is empty. Depictions of hourglasses in art survive in large numbers from antiquity to the present day, as a symbol for the passage of time. These were especially common sculpted as epitaphs on tombstones or other monuments, also in the form of the winged hourglass, a literal depiction of the well-known Latin epitaph tempus fugit ("time flies").
There are no records of the hourglass existing in Europe prior to the Early Middle Ages, such as invention by the Ancient Greeks; the first supported evidences appears from the 8th century CE, crafted by a Frankish monk named Liutprand who served at the cathedral in Chartres, France. But it was not until the 14th century that the hourglass was seen commonly, the earliest firm evidence being a depiction in the 1338 fresco Allegory of Good Government by Ambrogio Lorenzetti.
Use of the marine sandglass has been recorded since the 14th century. The written records about it were mostly from logbooks of European ships. In the same period it appears in other records and lists of ships stores. The earliest recorded reference that can be said with certainty to refer to a marine sandglass dates from c. 1345, in a receipt of Thomas de Stetesham, clerk of the King's ship La George, in the reign of Edward III of England; translated from the Latin, the receipt says: in 1345:
"The same Thomas accounts to have paid at Lescluse, in Flanders, for twelve glass horologes (" pro xii. orlogiis vitreis "), price of each 4½ gross', in sterling 9s. Item, For four horologes of the same sort (" de eadem secta "), bought there, price of each five gross', making in sterling 3s. 4d."
Marine sandglasses were very popular on board ships, as they were the most dependable measurement of time while at sea. Unlike the clepsydra, the motion of the ship while sailing did not affect the hourglass. The fact that the hourglass also used granular materials instead of liquids gave it more accurate measurements, as the clepsydra was prone to get condensation inside it during temperature changes. Seamen found that the hourglass was able to help them determine longitude, distance east or west from a certain point, with reasonable accuracy.
The hourglass also found popularity on land. As the use of mechanical clocks to indicate the times of events like church services became more common, creating a "need to keep track of time", the demand for time-measuring devices increased. Hourglasses were essentially inexpensive, as they required no rare technology to make and their contents were not hard to come by, and as the manufacturing of these instruments became more common, their uses became more practical.
Hourglasses were commonly seen in use in churches, homes, and work places to measure sermons, cooking time, and time spent on breaks from labor. Because they were being used for more everyday tasks, the model of the hourglass began to shrink. The smaller models were more practical and very popular as they made timing more discreet.
After 1500, the hourglass was not as widespread as it had been. This was due to the development of the mechanical clock, which became more accurate, smaller and cheaper, and made keeping time easier. The hourglass, however, did not disappear entirely. Although they became relatively less useful as clock technology advanced, hourglasses remained desirable in their design. The oldest known surviving hourglass resides in the British Museum in London.
Not until the 18th century did John Harrison come up with a marine chronometer that significantly improved on the stability of the hourglass at sea. Taking elements from the design logic behind the hourglass, he made a marine chronometer in 1761 that was able to accurately measure the journey from England to Jamaica accurate within five seconds.
Little written evidence exists to explain why its external form is the shape that it is glass bulbs used, however, have changed in style and design over time. While the main designs have always been ampoule in shape, the bulbs were not always connected. The first hourglasses were two separate bulbs with a cord wrapped at their union that was then coated in wax to hold the piece together and let sand flow in between. It was not until 1760 that both bulbs were blown together to keep moisture out of the bulbs and regulate the pressure within the bulb that varied the flow.
While some early hourglasses actually did use sand as the granular mixture to measure time, many did not use sand at all. The material used in most bulbs was a combination of "powdered marble, tin/lead oxides, and pulverized, burnt eggshell". Over time, different textures of granule matter were tested to see which gave the most constant flow within the bulbs. It was later discovered that for the perfect flow to be achieved the ratio of granule bead to the width of the bulb neck needed to be 1/12 or more but not greater than 1/2 the neck of the bulb.
Hourglasses were an early dependable and accurate measure of time. The rate of flow of the sand is independent of the depth in the upper reservoir, and the instrument will not freeze in cold weather. From the 15th century onwards, hourglasses were being used in a range of applications at sea, in the church, in industry, and in cookery.
During the voyage of Ferdinand Magellan around the globe, 18 hourglasses from Barcelona were in the ship's inventory, after the trip had been authorized by King Charles I of Spain. It was the job of a ship's page to turn the hourglasses and thus provide the times for the ship's log. Noon was the reference time for navigation, which did not depend on the glass, as the sun would be at its zenith. A number of sandglasses could be fixed in a common frame, each with a different operating time, e.g. as in a four-way Italian sandglass likely from the 17th century, in the collections of the Science Museum, in South Kensington, London, which could measure intervals of quarter, half, three-quarters, and one hour (and which were also used in churches, for priests and ministers to measure lengths of sermons).
While they are no longer widely used for keeping time, some institutions do maintain them. Both houses of the Australian Parliament use three hourglasses to time certain procedures, such as divisions.
The sandglass is still widely used as the kitchen egg timer; for cooking eggs, a three-minute timer is typical, hence the name "egg timer" for three-minute hourglasses. Egg timers are sold widely as souvenirs. Sand timers are also sometimes used in games such as Pictionary and Boggle to implement a time constraint on rounds of play.
The hourglass, sometimes with the addition of metaphorical wings, is often depicted as a symbol that human existence is fleeting, and that the "sands of time" will run out for every human life. It was used thus on pirate flags, to strike fear into the hearts of the pirates' victims. In England, hourglasses were sometimes placed in coffins, and they have graced gravestones for centuries. The hourglass was also used in alchemy as a symbol for hour.
The former Metropolitan Borough of Greenwich in London used an hourglass on its coat of arms, symbolising Greenwich's role as the origin of GMT. The district's successor, the Royal Borough of Greenwich, uses two hourglasses on its coat of arms.
Recognition of the hourglass as a symbol of time has survived its obsolescence as a timekeeper. For example, the American television soap opera Days of Our Lives, since its first broadcast in 1965, has displayed an hourglass in its opening credits, with the narration, "Like sands through the hourglass, so are the days of our lives," spoken by Macdonald Carey.
Various computer graphical user interfaces may change the pointer to an hourglass during a period when the program is in the middle of a task, and may not accept user input. During that period other programs, for example in different windows, may work normally. When such an hourglass does not disappear, it suggests a program is in an infinite loop and needs to be terminated, or is waiting for some external event (such as the user inserting a CD). Unicode has an HOURGLASS symbol at
Because of its symmetry, graphic signs resembling an hourglass are seen in the art of cultures which never encountered such objects. Vertical pairs of triangles joined at the apex are common in Native American art; both in North America, where it can represent, for example, the body of the Thunderbird or (in more elongated form) an enemy scalp, and in South America, where it is believed to represent a Chuncho jungle dweller. In Zulu textiles they symbolise a married man, as opposed to a pair of triangles joined at the base, which symbolise a married woman. Neolithic examples can be seen among Spanish cave paintings. Observers have even given the name "hourglass motif" to shapes which have more complex symmetry, such as a repeating circle and cross pattern from the Solomon Islands. Both the members of Project Tic Toc, from television series the Time Tunnel and the Challengers of the Unknown use symbols of the hourglass representing either time travel or time running out.
The Armed Forces Reserve Medal (AFRM) is a service medal of the United States Armed Forces that has existed since 1950. The medal recognizes service performed by members of the reserve components and is awarded to both officers and enlisted personnel. The medal is considered a successor award to the Naval Reserve Medal and the Marine Corps Reserve Ribbon, which were discontinued in 1958 and 1967, respectively.
If the medal is awarded for periods of service, it is accompanied by an hourglass device. Depending on the length of service, a bronze, silver, gold, or bronze and gold hourglass are worn on the suspension ribbon and service ribbon, indicating 10, 20, 30, or 40 years of service, respectively.
If the medal is awarded in connection with a mobilization, it is accompanied by an "M" device. Subsequent mobilizations under an unrelated presidential call-up order result in a numeral device being worn to indicate the number of mobilizations.Engraved Hourglass Nebula
The Engraved Hourglass Nebula (also known as MyCn 18) is a young planetary nebula in the southern constellation Musca. It was discovered by Annie Jump Cannon and Margaret W. Mayall during their work on an extended Henry Draper Catalogue (the catalogue was built between 1918 and 1924). At the time, it was designated simply as a small faint planetary nebula. Much improved telescopes and imaging techniques allowed the hourglass shape of the nebula to be discovered by Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory on January 18, 1996. It is conjectured that MyCn 18's hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles. The vivid colours given off by the nebula are the result of different 'shells' of elements being expelled from the dying star, in this case helium, nitrogen, oxygen and carbon.
The Hourglass Nebula was photographed by the Wide Field and Planetary Camera 2 of the Hubble Space Telescope.
A less-famous "Hourglass Nebula" is located inside the Lagoon Nebula.Freaky Friday (2018 film)
Freaky Friday is an American musical television film that premiered as a Disney Channel Original Movie on August 10, 2018. Based on the book Freaky Friday by Mary Rodgers and the Disney Theatrical Productions stage adaptation by Bridget Carpenter, the film stars Cozi Zuehlsdorff and Heidi Blickenstaff.Glossary of shapes with metaphorical names
Many shapes have metaphorical names, i.e., their names are metaphors: these shapes are named after a most common object that has it. For example, "U-shape" is a shape that resembles the letter U, a bell-shaped curve has the shape of the vertical cross-section of a bell, etc. These terms may variously refer to objects, their cross sections or projections.
Some of these names are "classical terms", i.e., words of Latin or Ancient Greek etymology. Others are English language constructs (although the base words may have non-English etymology). In some disciplines, where shapes of subjects in question are a very important consideration, the shape naming may be quite elaborate, see, e.g., the taxonomy of shapes of plant leaves in botany.
Aquiline, shaped like an eagle's beak (as in a Roman nose)
Biconic shape, a shape in a way opposite to the hourglass: it is based on two oppositely oriented cones or truncated cones with their bases joined; the cones are not necessarily the same
Bowtie shape, in two dimensions
Atmospheric reentry apparatus
Centerbody of an inlet cone in ramjets
Bullet Nose an open-ended hourglass
Cocked Hat curve, also known as Bicorn
Cone (from the Greek word for « pine cone »)
Egg-shaped, see "Oval", below
Fish bladder or Lens shape (the latter taking its name from the shape of the lentil seed)
Geoid (From Greek Ge (γη) for "Earth"), the term specifically introduced to denote the approximation of the shape of the Earth, which is approximately spherical, but not exactly so
Heart shape, long been used for its varied symbolism
Hourglass shape or hourglass figure, the one that resembles an hourglass; nearly symmetric shape wide at its ends and narrow in the middle; some flat shapes may be alternatively compared to the figure eight or hourglass
Dog bone shape, an hourglass with rounded ends
Lune, from the Latin word for the Moon
Maltese Cross curve
Mushroom shape, which became infamous as a result of the mushroom cloud
Oval (from the Latin "ovum" for egg), a descriptive term applied to several kinds of "rounded" shapes, including the egg shape
Pear shaped, in reference to the shape of a pear, i.e., a generally rounded shape, tapered towards the top and more spherical/circular at the bottom
Rod, a 3-dimensional, solid (filled) cylinder
Rod shaped bacteria
Scarabaeus curve resembling a scarab
Serpentine, shaped like a snake
Stadium, two half-circles joined by straight sides
Star a figure with multiple sharp points
TomahawkHour Glass (band)
Hour Glass was a 1960s rhythm and blues band based in Los Angeles, California in 1967 and 1968. Among their members were two future members of the Allman Brothers Band (Duane Allman and his brother Gregg) and three future studio musicians at the Fame Studios in Muscle Shoals, Alabama (Pete Carr, Johnny Sandlin and Paul Hornsby).Hourglass (Clannad song)
"Hourglass / Theme from Harry's Game" is a double A-side single by Irish musical group Clannad. It was released in 1989 to promote their best-of Past Present. This is the band's only single to feature a lead song that doesn't appear on any album, and the band's only double A-side single to date. Two promotional videos were produced to accompany the single, one for each of the lead songs, "Hourglass" directed by Tim Morris & Pól Brennan, and "Theme from Harry's Game" by Billy Magra.Hourglass (Dave Gahan album)
Hourglass is the second solo album by Depeche Mode singer Dave Gahan. It was released by Mute Records on 22 October 2007 in Europe, and received generally favourable reviews. Most critics complimented its electronica sound, while some criticised it for sounding too similar to Depeche Mode.Hourglass (James Taylor album)
Hourglass is singer-songwriter James Taylor's fourteenth studio album. Taylor's first studio album in six years was released in 1997 to glowing notices. It built upon the success of his previous effort, New Moon Shine.
Hourglass was an introspective album that earned Taylor his best critical reviews in almost twenty years. The album's lyrics focused largely on Taylor's troubled past and family. "Jump Up Behind Me" paid tribute to his father's rescue of him after The Flying Machine days, and the long drive from New York City back to his home in Chapel Hill. "Enough to Be On Your Way" was inspired by the alcoholism-related death of his brother Alex earlier in the decade. The themes were also inspired by Taylor's divorce from actress Kathryn Walker, which took place in 1996. Rolling Stone found that "one of the themes of this record is disbelief", while Taylor told the magazine that it was "spirituals for agnostics." Critics embraced the dark themes on the album, and Hourglass was a huge commercial success, reaching #9 on the Billboard 200 (Taylor's first Top 10 album in sixteen years) and also provided a big adult contemporary hit on "Little More Time With You". The album also gave Taylor his first Grammy since JT, when he was honored with Best Pop Album in 1998. The album also won producer/engineer Frank Filipetti a Grammy that year for Best Engineered Album. The majority of the album was recorded using Yamaha O2R and Tascam DA-88 machines, which were early digital devices not typically used by top level artists, as most major label records were still being recorded to analog tape at that time.
There is an enhanced CD version of the album containing interviews, photos, and videos.Hourglass (Squeeze song)
"Hourglass" was the first single released from Squeeze's seventh album, Babylon and On. Aided by an optical illusion-filled music video directed by Ade Edmondson and featured an appearance from former band member Jools Holland, that it received substantial airplay on MTV, "Hourglass" became the highest-charting hit the band ever had in the United States, peaking at number 15 on the Billboard Hot 100, while reaching number 16 in the UK Singles Chart.Hourglass corset
An hourglass corset is a garment that produces a silhouette resembling an hourglass shape characterized by wide hips, narrow waist (wasp waist), and wide bust.Hourglass dolphin
The hourglass dolphin (Lagenorhynchus cruciger) is a small dolphin in the family Delphinidae that inhabits Antarctic and subantarctic waters.
The dolphin has rarely been seen. It was identified as a new species by Jean René Constant Quoy and Joseph Paul Gaimard in 1824 from a drawing made in the South Pacific in 1820. It is the only cetacean to have been widely accepted as a species solely on witness accounts. By 1960, despite decades of whaling in the Southern Ocean, only three specimens had been recovered. As of 2010 only 6 complete and 14 partial specimens had been examined. Further information was obtained from 4 strandings and boats which searched for the dolphins in areas rarely visited by ships.
Though it is traditionally placed in the genus Lagenorhynchus, recent molecular analyses indicate that the hourglass dolphin is actually more closely related to the dolphins of the genus Cephalorhynchus.Lagenorhynchus
Lagenorhynchus is a genus in the order Cetacea, traditionally containing six species:
white-beaked dolphin, Lagenorhynchus albirostris
Atlantic white-sided dolphin, Lagenorhynchus acutus
Pacific white-sided dolphin, Lagenorhynchus obliquidens
dusky dolphin, Lagenorhynchus obscurus
Peale's dolphin, Lagenorhynchus australis
hourglass dolphin, Lagenorhynchus crucigerThe name Lagenorhynchus derives from the Greek lagenos meaning "bottle" and rhynchus meaning "beak". Indeed, the "bottle-nose" is a characteristic of this genus. However, the dolphins popularly called bottlenose dolphins belong in the genus Tursiops. The melon-headed whale was once classified in this genus, but was later removed to its own genus, Peponocephala.
Recent analysis of the mitochondrial cytochrome b gene indicates the genus Lagenorhynchus, as traditionally conceived, is not a natural (monophyletic) group. LeDuc, Perrin & Dizon 1999 found that the white-beaked and Atlantic white-sided dolphins were phylogenetically isolated within the Delphinidae, whereas the remaining four species were members of the Lissodelphinae, a predominantly Pacific clade of dolphins also including the right whale dolphins and the Cephalorhynchus dolphins. These findings are somewhat problematic taxonomically, since the white-beaked dolphin is the type species of the genus Lagenorhynchus; if the other species are not closely related to the white-beaked dolphin, then they must be removed from the genus. Accordingly, LeDuc et al. suggested that the Atlantic white-sided dolphin be placed within its own genus, Leucopleurus, and that the remaining species would need taxonomic revision, as well. Ledouc proposed Sagmatias as the new genus for the Pacific white-sided dolphin, Peale's dolphin, hourglass dolphin and dusky dolphin.May-Collado & Agnarsson 2006 actually recovered the hourglass and Peale's dolphins as nested phylogenetically among the species of Cephalorhynchus, and they suggest these two species be transferred to that genus. Some acoustic and morphological data support for this arrangement. Both hourglass and Peale's dolphins share with the species of Cephalorhynchus a distinct type of echolocation signal known as a narrow-band, high-frequency signal. This signal is shared with porpoises (Phocoenidae) and pygmy sperm whales (Kogiidae), but is not found among other dolphin groups. According to Schevill & Watkins 1971, Peale's dolphin and the Cephalorhynchus species are the only dolphins that do not whistle. Presumably this is the case for hourglass dolphins, as well. Peale's dolphin also shares with several Cephalorhynchus species the possession of a distinct white "armpit" marking behind the pectoral fin.
According to an analysis by May-Collado & Agnarsson 2006, the remaining two species, the dusky and Pacific white-sided dolphins, are closely related to each other and form the sister group to the (expanded) genus Cephalorhynchus. If this placement is accurate, a new genus name will need to be coined to accommodate these two species.Lucky Charms
Lucky Charms is a brand of cereal produced by the General Mills food company since 1964. The cereal consists of toasted oat pieces and multi-colored marshmallow shapes ("marbits" or marshmallow bits). The label features a leprechaun mascot, Lucky, animated in commercials.Marine sandglass
A marine sandglass is a timepiece of simple design that is a relative of the common hourglass, a marine (nautical) instrument known since the 14th century (although reasonably presumed to be of very ancient use and origin). They were employed to measure the time at sea or on a given navigational course, in repeated measures of small time increments (e.g., 30 minutes). Used together with the chip log, smaller marine sandglasses were also used to measure the boat speed through the water in knots.
Although vital to maritime navigation, marine sandglasses were not accurate measuring instruments for the passage of time; many design and environmental factors could affect the duration of sand's flow, and therefore its reported time. Their use continued through the early 19th century, when they were supplanted by reliable mechanical timepieces, and by other advances in marine navigation.
Marine sandglasses were very popular on board ships, as they were the most dependable measurement of time while at sea. Unlike the clepsydra, the motion of the ship while sailing did not affect the hourglass. The fact that the hourglass also used granular materials instead of liquids gave it more accurate measurements, as the clepsydra was prone to get condensation inside it during temperature changes. In conjunction with a record of a ship's speed and direction, seamen used the hourglass to determine their position with reasonable accuracy.Smallville (season 1)
Season one of Smallville, an American television series developed by Alfred Gough and Miles Millar, began airing on October 16, 2001, on The WB television network. The series recounts the early adventures of Kryptonian Clark Kent as he adjusts to his developing superpowers in the fictional town of Smallville, Kansas, during the years before he becomes Superman. The first season comprises 21 episodes and concluded its initial airing on May 21, 2002. Regular cast members during season one include Tom Welling, Kristin Kreuk, Michael Rosenbaum, Eric Johnson, Sam Jones III, Allison Mack, Annette O'Toole, and John Schneider.
The season's stories focus on Martha and Jonathan Kent's (O'Toole and Schneider) attempts to help their adopted son Clark (Welling) cope with his alien origin and control his developing superhuman abilities. Clark must deal with the meteor-infected individuals that begin appearing in Smallville, his love for Lana Lang (Kreuk), and not being able to tell his two best friends, Pete Ross (Jones III) and Chloe Sullivan (Mack), about his abilities or his origins. Clark also befriends Lex Luthor (Rosenbaum) after saving Lex's life. The season also follows Lex, as he tries to assert his independence from his father, Lionel Luthor (John Glover).
The episodes were filmed primarily in Vancouver and post-production work took place in Los Angeles. Gough and Millar assisted the writing staff with week-to-week story development. "Villain of the week" storylines were predominant during the first season; physical effects, make-up effects, and computer generated imagery became important components as well. Limited filming schedules sometimes forced guest actors to perform physical stunts, and the series regulars were more than willing to do stunt work. Episode budgets ultimately became strictly regulated, as the show frequently ran over budget during the first half of the season. The pilot broke The WB's viewership record for a debut series, and was nominated for various awards. Although the villain of the week storylines became a concern for producers, critical reception was generally favorable, and the series was noted as having a promising start. The first season was released on DVD on September 23, 2003, and included various special features that focused on individual episodes and the series as a whole. It has also been released on home media in regions 2 and 4 in the international markets.Syrtis Major Planum
Syrtis Major Planum is a "dark spot" (an albedo feature) located in the boundary between the northern lowlands and southern highlands of Mars just west of the impact basin Isidis in the Syrtis Major quadrangle. It was discovered, on the basis of data from Mars Global Surveyor, to be a low-relief shield volcano, but was formerly believed to be a plain, and was then known as Syrtis Major Planitia. The dark color comes from the basaltic volcanic rock of the region and the relative lack of dust.
A possible landing site for the Mars 2020 rover mission is Jezero crater (at 18.855°N 77.519°E / 18.855; 77.519) within the region. The northeastern region of Syrtis Major Planum is also considered a potential landing site.The Hourglass Sanatorium
The Hourglass Sanatorium (Polish: Sanatorium pod klepsydrą) is a 1973 Polish film directed by Wojciech Jerzy Has, starring Jan Nowicki, Tadeusz Kondrat, Mieczysław Voit, Halina Kowalska and Gustaw Holoubek. It is also known as The Sandglass in English-speaking countries. The story follows a young Jewish man who visits his father in a mystical sanatorium where time does not behave normally. The film is an adaptation of Bruno Schulz's story collection Sanatorium Under the Sign of the Hourglass. It won the Jury Prize at the 1973 Cannes Film Festival.
|Philosophy of time|
and use of time
|Time in physics|
|Archaeology and geology|
|Other units of time|