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72-502: The original typhoon shelter was built after the 1874 typhoon , at the present location of Victoria Park , to provide shelter for fishing boats during storms. It was completed in 1883 with a breakwater only 427 metres (1,400 feet) long. The cost was HK$ 96,500. In December 1903, a legislative council member, Gershom Stewart , suggested that the typhoon shelter be expanded. The motion was passed but expansion works could not be carried out due to lack of capital. The Legislative Council and

144-550: A barometric scale with finer graduations "Stormy (28 inches of mercury), Much Rain (28.5), Rain (29), Change (29.5), Fair (30), Set fair (30.5), very dry(31)". Natalo Aiano is recognised as one of the finest makers of wheel barometers, an early pioneer in a wave of artisanal Italian instrument and barometer makers that were encouraged to emigrate to the UK. He listed as working in Holborn, London c.  1785 –1805. From 1770 onwards

216-624: A better way to attempt to produce a vacuum other than with a siphon. Magiotti devised such an experiment. Four accounts of the experiment exist, all written some years later. No exact date was given, but since Two New Sciences reached Rome in December 1638, and Berti died before January 2, 1644, science historian W. E. Knowles Middleton places the event to sometime between 1639 and 1643. Present were Berti, Magiotti, Jesuit polymath Athanasius Kircher , and Jesuit physicist Niccolò Zucchi . In brief, Berti's experiment consisted of filling with water

288-442: A few aneroid barometers intended for monitoring the weather are calibrated to manually adjust for altitude. In this case, knowing either the altitude or the current atmospheric pressure would be sufficient for future accurate readings. The table below shows examples for three locations in the city of San Francisco , California . Note the corrected barometer readings are identical, and based on equivalent sea-level pressure. (Assume

360-593: A large number of Italians came to England because they were accomplished glass blowers or instrument makers. By 1840 it was fair to say that the Italians dominated the industry in England. Using vacuum pump oil as the working fluid in a barometer has led to the creation of the new "World's Tallest Barometer" in February 2013. The barometer at Portland State University (PSU) uses doubly distilled vacuum pump oil and has

432-513: A liquid that was heavier than water, and from his previous association and suggestions by Galileo, he deduced that by using mercury , a shorter tube could be used. With mercury, which is about 14 times denser than water, a tube only 80 cm was now needed, not 10.5 m. In 1646, Blaise Pascal along with Pierre Petit , had repeated and perfected Torricelli's experiment after hearing about it from Marin Mersenne , who himself had been shown

504-405: A long tube that had both ends plugged, then standing the tube in a basin of water. The bottom end of the tube was opened, and water that had been inside of it poured out into the basin. However, only part of the water in the tube flowed out, and the level of the water inside the tube stayed at an exact level, which happened to be 10.3 m (34 ft), the same height limit Baliani had observed in

576-427: A manifest cause from which the resistance can be derived which is felt if we try to make a vacuum, it seems to me foolish to try to attribute to vacuum those operations which follow evidently from some other cause; and so by making some very easy calculations, I found that the cause assigned by me (that is, the weight of the atmosphere) ought by itself alone to offer a greater resistance than it does when we try to produce

648-442: A mercury thermometer is usually mounted on the instrument. Temperature compensation of an aneroid barometer is accomplished by including a bi-metal element in the mechanical linkages. Aneroid barometers sold for domestic use typically have no compensation under the assumption that they will be used within a controlled room temperature range. As the air pressure decreases at altitudes above sea level (and increases below sea level)

720-422: A method that does not involve liquid . Invented in 1844 by French scientist Lucien Vidi , the aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule), which is made from an alloy of beryllium and copper . The evacuated capsule (or usually several capsules, stacked to add up their movements) is prevented from collapsing by a strong spring. Small changes in external air pressure cause

792-511: A mountain called the Puy de Dôme , asking him to perform a crucial experiment. Perier was to take a barometer up the Puy de Dôme and make measurements along the way of the height of the column of mercury. He was then to compare it to measurements taken at the foot of the mountain to see if those measurements taken higher up were in fact smaller. In September 1648, Perier carefully and meticulously carried out

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864-458: A nominal height of about 12.4 m for the oil column height; expected excursions are in the range of ±0.4 m over the course of a year. Vacuum pump oil has very low vapour pressure and it is available in a range of densities; the lowest density vacuum oil was chosen for the PSU barometer to maximize the oil column height. An aneroid barometer is an instrument used for measuring air pressure as

936-427: A pressure instrument in radiosondes . A barograph is a recording aneroid barometer where the changes in atmospheric pressure are recorded on a paper chart. The principle of the barograph is same as that of the aneroid barometer. Whereas the barometer displays the pressure on a dial, the barograph uses the small movements of the box to transmit by a system of levers to a recording arm that has at its extreme end either

1008-696: A scribe or a pen. A scribe records on smoked foil while a pen records on paper using ink, held in a nib. The recording material is mounted on a cylindrical drum which is rotated slowly by a clock. Commonly, the drum makes one revolution per day, per week, or per month and the rotation rate can often be selected by the user. Microelectromechanical systems (or MEMS) barometers are extremely small devices between 1 and 100 micrometres in size (0.001 to 0.1 mm). They are created via photolithography or photochemical machining . Typical applications include miniaturized weather stations, electronic barometers and altimeters. A barometer can also be found in smartphones such as

1080-402: A sealed body, half filled with water. A narrow spout connects to the body below the water level and rises above the water level. The narrow spout is open to the atmosphere. When the air pressure is lower than it was at the time the body was sealed, the water level in the spout will rise above the water level in the body; when the air pressure is higher, the water level in the spout will drop below

1152-465: A temperature of 15 °C.) In 1787, during a scientific expedition on Mont Blanc , De Saussure undertook research and executed physical experiments on the boiling point of water at different heights. He calculated the height at each of his experiments by measuring how long it took an alcohol burner to boil an amount of water, and by these means he determined the height of the mountain to be 4775 metres. (This later turned out to be 32 metres less than

1224-407: A thumbscrew pressing on a leather diaphragm bottom (V in the diagram). This compensates for displacement of mercury in the column with varying pressure. To use a Fortin barometer, the level of mercury is set to zero by using the thumbscrew to make an ivory pointer (O in the diagram) just touch the surface of the mercury. The pressure is then read on the column by adjusting the vernier scale so that

1296-486: A vacuum, and since he was the first to view it this way, he is traditionally considered the inventor of the barometer, in the sense in which we now use the term. Because of rumors circulating in Torricelli's gossipy Italian neighbourhood, which included that he was engaged in some form of sorcery or witchcraft, Torricelli realized he had to keep his experiment secret to avoid the risk of being arrested. He needed to use

1368-544: A vacuum. It was traditionally thought, especially by the Aristotelians , that the air did not have weight; that is, that the kilometers of air above the surface of the Earth did not exert any weight on the bodies below it. Even Galileo had accepted the weightlessness of air as a simple truth. Torricelli proposed that rather than an attractive force of the vacuum sucking up water, air did indeed have weight, which pushed on

1440-666: A working area for construction of the Central–Wan Chai Bypass (the working for Route 4 Reengineering), an underground road, underworks that were part of the Wan Chai Phase II project of the Central and Wan Chai Reclamation , begun in 2009. In 2022, the section of harbourfront alongside the shelter, roughly aligning with Victoria Park, was redeveloped and expanded, as part of the overall development of Victoria Harbour waterfront. A 2005 government report singled out

1512-466: Is 1013 hPa (mbar). The word barometer is derived from the Ancient Greek βάρος ( báros ), meaning "weight", and μέτρον ( métron ), meaning "measure". Evangelista Torricelli is usually credited with inventing the barometer in 1643, although the historian W. E. Knowles Middleton suggests the more likely date is 1644 (when Torricelli first reported his experiments; the 1643 date

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1584-412: Is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to help find surface troughs , pressure systems and frontal boundaries . Barometers and pressure altimeters (the most basic and common type of altimeter) are essentially

1656-418: Is a traditional mercury thermometer that is needed to calculate the expansion or contraction of the fluid in the barometer. The other is the barometer, consisting of a J-shaped tube open at the lower end and closed at the top, with small reservoirs at both ends of the tube. A wheel barometer uses a "J" tube sealed at the top of the longer limb. The shorter limb is open to the atmosphere and floating on top of

1728-406: Is equivalent to 29.92 inches (760 mm) of mercury. Design changes to make the instrument more sensitive, simpler to read, and easier to transport resulted in variations such as the basin, siphon, wheel, cistern, Fortin, multiple folded, stereometric, and balance barometers. In 2007, a European Union directive was enacted to restrict the use of mercury in new measuring instruments intended for

1800-424: Is no evidence that he built a working barometer at that time. On 27 July 1630, Giovanni Battista Baliani wrote a letter to Galileo Galilei explaining an experiment he had made in which a siphon , led over a hill about 21 m high, failed to work. When the end of the siphon was opened in a reservoir, the water level in that limb would sink to about 10 m above the reservoir. Galileo responded with an explanation of

1872-409: Is only mercury vapour above this point and its pressure is very low relative to the atmospheric pressure. Therefore, one can find the atmospheric pressure using the barometer and this equation: where ρ is the density of mercury, g is the gravitational acceleration, and h is the height of the mercury column above the free surface area. The physical dimensions (length of tube and cross-sectional area of

1944-450: Is similar to resetting an analog clock that is not at the correct time. Its dial is rotated so that the current atmospheric pressure from a known accurate and nearby barometer (such as the local weather station ) is displayed. No calculation is needed, as the source barometer reading has already been converted to equivalent sea-level pressure, and this is transferred to the barometer being set—regardless of its altitude. Though somewhat rare,

2016-414: Is used to keep track of the contents of the diver's air tank. Another gauge is used to measure the hydrostatic pressure, usually expressed as a depth of sea water. Either or both gauges may be replaced with electronic variants or a dive computer. The density of mercury will change with increase or decrease in temperature, so a reading must be adjusted for the temperature of the instrument. For this purpose

2088-686: The Carlist Wars , and originally bound for the Philippines. Captain Superintendent of Police Walter Meredith Deane attracted severe criticism for ordering his men confined to barracks rather than to risk rescue of the crews on the wrecked vessels Leonor and Albay . Refusing calls for a public inquiry, Governor Sir Arthur Kennedy passed all papers on the matter to Secretary of State Lord Carnarvon who affirmed Kennedy's decision. Pictures Barometer A barometer

2160-553: The Causeway Bay Typhoon Shelter as having "exceptionally high levels" of tributyltin , exceeding 1000 times the baseline concentration measured in the East Lamma Channel . To the west: To the south: To the east: 22°17′09″N 114°11′07″E  /  22.28570°N 114.18520°E  / 22.28570; 114.18520 1874 Hong Kong typhoon The 1874 Hong Kong Typhoon

2232-654: The Hong Kong Chamber of Commerce questioned the Hong Kong Government on the expansion in 1904 and 1906, but the Government did not give any response. On 18 September 1906, a typhoon struck Hong Kong, destroying 3,653 boats and killing 15,000 people, most of them fishermen. In March 1908, the Government finally carried out expansion works on the typhoon shelter, deepening it by 3 metres (9 feet) and expanded it to 30 hectares (75 acres). In 1953,

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2304-533: The Samsung Galaxy Nexus , Samsung Galaxy S3-S6, Motorola Xoom, Apple iPhone 6 and newer iPhones, and Timex Expedition WS4 smartwatch , based on MEMS and piezoresistive pressure-sensing technologies. Inclusion of barometers on smartphones was originally intended to provide a faster GPS lock. However, third party researchers were unable to confirm additional GPS accuracy or lock speed due to barometric readings. The researchers suggest that

2376-537: The Shark Oil barometer, work only in a certain temperature range, achieved in warmer climates. Barometric pressure and the pressure tendency (the change of pressure over time) have been used in weather forecasting since the late 19th century. When used in combination with wind observations, reasonably accurate short-term forecasts can be made. Simultaneous barometric readings from across a network of weather stations allow maps of air pressure to be produced, which were

2448-404: The actual height of 4807 metres). For these experiments De Saussure brought specific scientific equipment, such as a barometer and thermometer . His calculated boiling temperature of water at the top of the mountain was fairly accurate, only off by 0.1 kelvin. Based on his findings, the altimeter could be developed as a specific application of the barometer. In the mid-19th century, this method

2520-487: The bay. At this time Hong Kong did not have its own weather observatory and many people were expecting the storm from a different direction, while others were caught off guard and either shipwrecked or lost their homes. A few false typhoon alerts had been announced earlier in the year. The next morning, the Praya scene from west to east was heart-rending: one could easily find boats capsized and corpses floating and drifting on

2592-447: The cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. Many models include a manually set needle which is used to mark the current measurement so a change can be seen. This type of barometer is common in homes and in recreational boats . It is also used in meteorology , mostly in barographs and as

2664-426: The change in pressure, especially if more than 3.5 hPa (0.1 inHg), the greater the change in weather that can be expected. If the pressure drop is rapid, a low pressure system is approaching, and there is a greater chance of rain. Rapid pressure rises , such as in the wake of a cold front , are associated with improving weather conditions, such as clearing skies. With falling air pressure, gases trapped within

2736-401: The city was destroyed. Buildings around Praia Grande were destroyed, leaving the coast with sand. The streets and houses in the colony were annihilated. Fortaleza do Monte was damaged, with a torn off roof and collapsed walls. St. Joseph's Seminary and Church was nearly destroyed, with two walls remaining. 300,000 patacas worth of goods were destroyed in the storm, tea and olive oil being

2808-535: The coal in deep mines can escape more freely. Thus low pressure increases the risk of firedamp accumulating. Collieries therefore keep track of the pressure. In the case of the Trimdon Grange colliery disaster of 1882 the mines inspector drew attention to the records and in the report stated "the conditions of atmosphere and temperature may be taken to have reached a dangerous point". Aneroid barometers are used in scuba diving . A submersible pressure gauge

2880-569: The costliest. It was estimated that over 5,000 people have died in Macau, and damages costs around 400,000 patacas . Around 2,000 ships were also sunk during the storm. The damage in the colony were reportedly worse than Paris during Franco-Prussian War , or the recent earthquake in the Philippines. It was considered the worst storm to hit Macau in history. Most of the 37 ships in port were damaged and hundreds of fishing junks and sampans were either wrecked or broken up despite having sought shelter in

2952-559: The experiment by Torricelli toward the end of 1644. Pascal further devised an experiment to test the Aristotelian proposition that it was vapours from the liquid that filled the space in a barometer. His experiment compared water with wine, and since the latter was considered more "spiritous", the Aristotelians expected the wine to stand lower (since more vapours would mean more pushing down on the liquid column). Pascal performed

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3024-488: The experiment publicly, inviting the Aristotelians to predict the outcome beforehand. The Aristotelians predicted the wine would stand lower. It did not. However, Pascal went even further to test the mechanical theory. If, as suspected by mechanical philosophers like Torricelli and Pascal, air had weight, the pressure would be less at higher altitudes. Therefore, Pascal wrote to his brother-in-law, Florin Perier, who lived near

3096-413: The experiment, and found that Pascal's predictions had been correct. The column of mercury stood lower as the barometer was carried to a higher altitude. The concept that decreasing atmospheric pressure predicts stormy weather, postulated by Lucien Vidi , provides the theoretical basis for a weather prediction device called a "weather glass" or a "Goethe barometer" (named for Johann Wolfgang von Goethe ,

3168-436: The first form of the modern weather map when created in the 19th century. Isobars , lines of equal pressure, when drawn on such a map, give a contour map showing areas of high and low pressure. Localized high atmospheric pressure acts as a barrier to approaching weather systems, diverting their course. Atmospheric lift caused by low-level wind convergence into the surface brings clouds and sometimes precipitation . The larger

3240-419: The float and turning the dial the other way. Around 1810 the wheel barometer, which could be read from a great distance, became the first practical and commercial instrument favoured by farmers and the educated classes in the UK. The face of the barometer was circular with a simple dial pointing to an easily readable scale: "Rain - Change - Dry" with the "Change" at the top centre of the dial. Later models added

3312-462: The general public, effectively ending the production of new mercury barometers in Europe. The repair and trade of antiques (produced before late 1957) remained unrestricted. Fitzroy barometers combine the standard mercury barometer with a thermometer, as well as a guide of how to interpret pressure changes. Fortin barometers use a variable displacement mercury cistern, usually constructed with

3384-404: The incident, Brazilian astronomer Francisco Antônio de Almeida , in his 1879 account describes an episode of arson and looting at two warehouses in which foreigners were murdered, for which the two Chinese perpetrators were sentenced to death. Almeida also cites English newspapers of the time who estimated up to eight thousand people killed in the typhoon, many of them being Spanish families fleeing

3456-564: The inclusion of barometers in smartphones may provide a solution for determining a user's elevation, but also suggest that several pitfalls must first be overcome. There are many other more unusual types of barometer. From variations on the storm barometer, such as the Collins Patent Table Barometer, to more traditional-looking designs such as Hooke's Otheometer and the Ross Sympiesometer. Some, such as

3528-459: The mercury + head space + the maximum length of the column. Torricelli documented that the height of the mercury in a barometer changed slightly each day and concluded that this was due to the changing pressure in the atmosphere . He wrote: "We live submerged at the bottom of an ocean of elementary air, which is known by incontestable experiments to have weight". Inspired by Torricelli, Otto von Guericke on 5 December 1660 found that air pressure

3600-468: The mercury just touches the sightline at Z. Some models also employ a valve for closing the cistern, enabling the mercury column to be forced to the top of the column for transport. This prevents water-hammer damage to the column in transit. A sympiesometer is a compact and lightweight barometer that was widely used on ships in the early 19th century. The sensitivity of this barometer was also used to measure altitude. Sympiesometers have two parts. One

3672-424: The mercury there is a small glass float. A fine silken thread is attached to the float which passes up over a wheel and then back down to a counterweight (usually protected in another tube). The wheel turns the point on the front of the barometer. As atmospheric pressure increases mercury moves from the short to the long limb, the float falls and the pointer moves. When pressure falls the mercury moves back, lifting

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3744-622: The phenomenon: he proposed that it was the power of a vacuum that held the water up, and at a certain height the amount of water simply became too much and the force could not hold any more, like a cord that can support only so much weight. This was a restatement of the theory of horror vacui ("nature abhors a vacuum"), which dates to Aristotle , and which Galileo restated as resistenza del vacuo . Galileo's ideas, presented in his Discorsi ( Two New Sciences ), reached Rome in December 1638. Physicists Gasparo Berti and father Raffaello Magiotti were excited by these ideas, and decided to seek

3816-401: The renowned German writer and polymath who developed a simple but effective weather ball barometer using the principles developed by Torricelli ). The French name, le baromètre Liègeois , is used by some English speakers. This name reflects the origins of many early weather glasses – the glass blowers of Liège , Belgium . The weather ball barometer consists of a glass container with

3888-418: The reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir. Since higher temperature levels around the instrument will reduce the density of the mercury, the scale for reading the height of the mercury is adjusted to compensate for this effect. The tube has to be at least as long as the amount dipping in

3960-425: The same if there are negligible changes in time, horizontal distance, and temperature. If this were not done, there would be a false indication of an approaching storm at the higher elevation. Aneroid barometers have a mechanical adjustment that allows the equivalent sea level pressure to be read directly and without further adjustment if the instrument is not moved to a different altitude. Setting an aneroid barometer

4032-445: The same instrument, but used for different purposes. An altimeter is intended to be used at different levels matching the corresponding atmospheric pressure to the altitude , while a barometer is kept at the same level and measures subtle pressure changes caused by weather and elements of weather. The average atmospheric pressure on the Earth's surface varies between 940 and 1040 hPa (mbar). The average atmospheric pressure at sea level

4104-407: The siphon. What was most important about this experiment was that the lowering water had left a space above it in the tube which had no intermediate contact with air to fill it up. This seemed to suggest the possibility of a vacuum existing in the space above the water. Evangelista Torricelli, a friend and student of Galileo, interpreted the results of the experiments in a novel way. He proposed that

4176-417: The south of Hong Kong at its closest approach, similar to Hato in 2017. The typhoon began weakening after 03:00 AM. In Kwangtung province , at least 10,000 people died in the storm, with some reporting up to 100,000. The typhoon hit Hong Kong with "unprecedented violence" and left no less than 2,000 people injured. Some adventurers went out to the Praya at 11:00 PM and found themselves knee deep in

4248-453: The tube) of the barometer itself have no effect on the height of the fluid column in the tube. In thermodynamic calculations, a commonly used pressure unit is the "standard atmosphere". This is the pressure resulting from a column of mercury of 760 mm in height at 0 °C. For the density of mercury, use ρ Hg = 13,595 kg/m and for gravitational acceleration use g = 9.807 m/s . If water were used (instead of mercury) to meet

4320-498: The typhoon shelter was moved northwards to its present site and the original typhoon shelter was reclaimed to provide land for Victoria Park. The new typhoon shelter had a size of 26 hectares (65 acres). However, reclamation projects which started in the typhoon shelter during the late 1960s to construct the Cross-Harbour Tunnel decreased the size of the typhoon shelter. Much of the shelter was temporarily reclaimed as

4392-417: The uncorrected reading of the barometer will depend on its location. The reading is then adjusted to an equivalent sea-level pressure for purposes of reporting. For example, if a barometer located at sea level and under fair weather conditions is moved to an altitude of 1,000 feet (305 m), about 1 inch of mercury (~35 hPa) must be added on to the reading. The barometer readings at the two locations should be

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4464-532: The water and risked being washed away by the waves hitting the shore. They were forced to retreat by 01:00 AM as the winds were reaching a new high. The East Point on Causeway Bay recorded a water level 4 feet above its average. Many stores and shops, even far away from the Praya waterfront were flooded and water damaged. The storm's two-hour impact had injured and killed many in the Colony. Telegraphic communication

4536-455: The water level in the body. A variation of this type of barometer can be easily made at home. A mercury barometer is an instrument used to measure atmospheric pressure in a certain location and has a vertical glass tube closed at the top sitting in an open mercury-filled basin at the bottom. Mercury in the tube adjusts until the weight of it balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on

4608-541: The water with some bodies washed ashore by the high tides. The sizeable Stonecutters' Island Gaol was left in ruins and both the Police Courts and Victoria Gaol were unroofed. The damage overall was considered "incalculable". Ernst Eitel recounted how many of the European and Chinese houses were ruined and became roofless; big trees were unrooted and corpses were found in the ruins and started surfacing at

4680-428: The water, holding up a column of it. He argued that the level that the water stayed at—c. 10.3 m above the water surface below—was reflective of the force of the air's weight pushing on the water in the basin, setting a limit for how far down the water level could sink in a tall, closed, water-filled tube. He viewed the barometer as a balance—an instrument for measurement—as opposed to merely an instrument for creating

4752-480: The waterfront from the wrecked ships. A visitor arriving on a steamer from Peking during the typhoon reported that the waterfront was nearly swept away, hardly a tree was left standing in the Botanical Gardens and many buildings were found roofless and in ruins. People were hastily burying the dead for the heat was intense and there was great concern over the outbreak of contagious diseases. Following

4824-448: The weight of the atmosphere, not an attracting force of the vacuum, held the water in the tube. In a letter to Michelangelo Ricci in 1644 concerning the experiments, he wrote: Many have said that a vacuum does not exist, others that it does exist in spite of the repugnance of nature and with difficulty; I know of no one who has said that it exists without difficulty and without a resistance from nature. I argued thus: If there can be found

4896-544: Was interrupted and communication with Hong Kong Island was cut for a time. The town had sustained great loss, its roads were deserted and strewn with debris, house roofs were ruined, windows shattered and walls fallen and cables and gas pipes were blown away and trees uprooted. The small Portuguese colony received extreme damage from the typhoon. The barometer reported the pressure of 28 inHg (950 hPa). The damaged steamer Poyang arrived in Hong Kong, reporting that

4968-417: Was only suggested after his death). Gasparo Berti , an Italian mathematician and astronomer, also built a rudimentary water barometer sometime between 1640 and 1644, but it was not a true barometer as it was not intended to move and record variable air pressure. French scientist and philosopher René Descartes described the design of an experiment to determine atmospheric pressure as early as 1631, but there

5040-530: Was the third-worst typhoon to ever hit Hong Kong , striking during the night of September 22, 1874 and the morning of September 23, 1874. The Colony experienced a period of low pressure, typical of the eye of a typhoon. From 08:00 PM, winds raged and howled with ear-deafening sounds, alongside the painful cries of many people who had become homeless. The typhoon increased in strength steadily up to 02:15 AM on September 23. Modern analysis in 2017 indicated that this great typhoon passed approximately 50 to 60 km to

5112-472: Was unusually low and predicted a storm, which occurred the next day. The mercury barometer's design gives rise to the expression of atmospheric pressure in inches or millimeters of mercury (mmHg). A torr was originally defined as 1 mmHg. The pressure is quoted as the level of the mercury's height in the vertical column. Typically, atmospheric pressure is measured between 26.5 inches (670 mm) and 31.5 inches (800 mm) of Hg. One atmosphere (1 atm)

5184-444: Was used by explorers. When atmospheric pressure is measured by a barometer, the pressure is also referred to as the "barometric pressure". Assume a barometer with a cross-sectional area A , a height h , filled with mercury from the bottom at Point B to the top at Point C. The pressure at the bottom of the barometer, Point B, is equal to the atmospheric pressure. The pressure at the very top, Point C, can be taken as zero because there

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