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Hourglass
An hourglass (or sandglass, sand timer, or sand clock) 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 flow of a substance (historically sand) from the upper bulb to the lower one due to gravity. Typically, the upper and lower bulbs are symmetric as they are usually manufactured by pinching a tube. The specific duration of time a given hourglass measures is determined by factors including the quantity and coarseness of the particulate matter and the neck width. Depictions of an hourglass as a symbol of the passage of time are found in art, especially on tombstones or other monuments, from antiquity to the present day. The form of a winged hourglass has been used as a literal depiction of the Latin phrase ("time flies"). History Antiquity The origin of the hourglass is unclear. Its predecessor the ''clepsydra'', or water clock, is known to have existed in Babylon and Egypt as early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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). Sandglasses were used 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 ships, as they were the most dependable measurement of tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time
Time is the continuous progression of existence that occurs in an apparently irreversible process, irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequence events, to compare the duration of events (or the intervals between them), and to quantify rates of change of quantities in material reality or in the qualia, conscious experience. Time is often referred to as a fourth dimension, along with Three-dimensional space, three spatial dimensions. Time is one of the seven fundamental physical quantities in both the International System of Units (SI) and International System of Quantities. The SI base unit of time is the second, which is defined by measuring the electronic transition frequency of caesium atoms. General relativity is the primary framework for understanding how spacetime works. Through advances in both theoretical and experimental investigations of spacetime, it has been shown ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand. One such example of this is aragonite, which has been created over the past 500million years by various forms of life, such as coral and shellfish. It is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years, as in the Caribbean. Somewhat more rarely, sand may be composed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg Timer
An egg timer or kitchen timer is a device whose primary function is to assist in timing during cooking; the name comes from the first timers initially being used for the timing of cooking eggs. Early designs simply counted down for a specific period of time. Some modern designs can time more accurately by depending on water temperature rather than an absolute time. Technology Traditionally egg timers were small hourglasses and the name has come to be synonymous with this form. As technology progressed mechanical countdown timers were developed which had an adjustable dial and could be applied to a wide range of timed cooking tasks. Most recently digital timers have also been manufactured and a wide selection of software is available to perform this task on a computer or mobile phone. The task is simple to perform on most microwaves and oven timers. New products have been developed which potentially allow for better egg timing; these use the temperature of the water in which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tempus Fugit
''Tempus fugit'' () is a Latin phrase, usually translated into English as "time flies". The expression comes from line 284 of book 3 of Virgil's ''Georgics'', Vergilius Maro, Publius. ''Georgicon'', III. c. 29 BC. Hosted at Wikisource. where it appears as ''fugit'' ''irreparabile'' ''tempus'': "it escapes, irretrievable time". The phrase is used in both its Latin and English forms as a proverb that "time's a-wasting". Usage ''Tempus fugit'' is typically employed as an admonition against sloth and procrastination (cf. ''carpe diem'') rather than an argument for licentiousness (cf. " gather ye rosebuds while ye may"); the English form is often merely descriptive: "time flies like the wind", "time flies when you're having fun". The phrase is a common motto, particularly on sundials and clocks. It also has been used on gravestones. Some writers have attempted rebuttals: "Time goes, you say? Ah, no! alas, time stays, we go." by Henry Austin Dobson (1840–1921)." ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambrogio Lorenzetti
Ambrogio Lorenzetti (; – after 9 August 1348) was an Italian painter of the Sienese school. He was active from approximately 1317 to 1348. He painted ''The Allegory of Good and Bad Government'' in the Sala dei Nove (Salon of Nine or Council Room) in Siena's Palazzo Pubblico. His elder brother was the painter Pietro Lorenzetti. Biography Lorenzetti was highly influenced by both Italo-Byzantine art and classical art forms, and used these to create a unique and individualistic style of painting. His work was exceptionally original. Individuality at this time was unusual due to the influence of patronage on art. Because paintings were often commissioned, individualism in art was infrequently seen. It is known that Lorenzetti engaged in artistic pursuits that were thought to have their origins during the Renaissance, such as experimenting with Perspective (graphical), perspective and physiognomy, and studying classical antiquity.Chiara Frugoni, ''Pietro and Ambrogio Lorenzetti'', (F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Harrison
John Harrison ( – 24 March 1776) was an English carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the History of longitude, problem of how to calculate longitude while at sea. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved had been considered so important following the Scilly naval disaster of 1707 that the Parliament of Great Britain, British Parliament was offering financial rewards of up to £20,000 (equivalent to £ in ) under the 1714 Longitude Act, though Harrison never received the full reward due to political rivalries. He presented his first design in 1730, and worked over many years on improved designs, making several advances in time-keeping technology, finally turning to what were called sea watches. Harrison gained support from the Board of Longitude, Longitude Board in building and testing his designs. Towards the end of his life, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine Chronometer
A marine chronometer is a precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation. It is used to determine longitude by comparing Greenwich Mean Time (GMT), and the time at the current location found from observations of celestial bodies. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective navigation, lacking electronic or communications aids. The first true chronometer was the life work of one man, John Harrison, spanning 31 years of persistent experimentation and testing that revolutionized naval (and later aerial) navigation. The term ''wikt:chronometer, chronometer'' was coined from the Greek words () (meaning time) and (meaning measure). The 1713 book ''Physico-Theology'' by the English cleric and scientist William Derham includes one of the earliest theoretical descriptions of a marine chronome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marble
Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or Dolomite (mineral), dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is typically not Foliation (geology), foliated (Layered intrusion, layered), although there are exceptions. In geology, the term ''marble'' refers to metamorphosed limestone, but its use in stonemasonry more broadly encompasses unmetamorphosed limestone. The extraction of marble is performed by quarrying. Marble production is dominated by four countries: China, Italy, India and Spain, which account for almost half of world production of marble and decorative stone. Because of its high hardness and strong wear resistance, and because it will not be deformed by temperature, marble is often used in Marble sculpture, sculpture and construction. Etymology The word "marble" derives from the Ancient Greek (), from (), "crystalline rock, shin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
