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66-559: Originally shallow in depth, the westernmost parts of creek have since been dredged and the original river connected to a canal system. This effort was spearheaded as a part of flood mitigation efforts in the 1940s by the Florida State Board of Conservation , who lobbied for the creation of South Florida Water Management District in 1948. The flood protection system intensified after extensive flooding in South Florida following

132-402: A dragline . This technique is often used in excavation of bay mud . Most of these dredges are crane barges with spuds , steel piles that can be lowered and raised to position the dredge. A backhoe/dipper dredger has a backhoe like on some excavators . A crude but usable backhoe dredger can be made by mounting a land-type backhoe excavator on a pontoon . The six largest backhoe dredgers in

198-482: A capacity of 6,000 cubic metres per hour (59,000 cu ft/ks). An even larger dredger, retired in 1980, was the U.S. Army Corps of Engineers Essayons , which was 525.17 feet (160.07 m) long. The Mallard II , a clamshell dredger that maintains levees in San Francisco Bay , has operated continuously since being built in 1936. Dredgers are often equipped with dredge monitoring software to help

264-439: A few different types of dredge hoses that differ in terms of working pressure, float-ability, armored or not etc. Suction hoses, discharge armored hoses and self-floating hoses are some of the popular types engineered for transporting and discharging dredge materials. Some even had the pipes or hoses customised to exact dredging needs etc. Other times, it is pumped into barges (also called scows ), which deposit it elsewhere while

330-567: A few situations the excavation is undertaken by a specialist floating plant , known as a dredger. Usually the main objectives of dredging is to recover material of value, or to create a greater depth of water. Dredging systems can either be shore-based, brought to a location based on barges , or built into purpose-built vessels. Dredging can have environmental impacts: it can disturb marine sediments , leading to both short- and long-term water pollution , damage or destroy seabed ecosystems , and can release legacy human-sourced toxins captured in

396-478: A long tube like some vacuum cleaners but on a larger scale. A plain suction dredger has no tool at the end of the suction pipe to disturb the material. A trailing suction hopper dredger (TSHD) trails its suction pipe when working. The pipe, which is fitted with a dredge drag head , loads the dredge spoil into one or more hoppers in the vessel. When the hoppers are full, the TSHD sails to a disposal area and either dumps

462-778: A practical use. These include mechanical fountains, a "hurricane" lamp, self-trimming and self-feeding lamps, a form of gas mask for use underground, and a grabbing tool , constructed in the same way as a modern clamshell grab, for recovering underwater objects. The book's other inventions are ingeniously built pouring vessels, designed to puzzle guests at parties. It is thought that some of these models were never constructed. The inventions employ innovative engineering ideas, such as automatic one-way and two-way valves , mechanical memories, devices capable of responding to feedback , and delay mechanisms. Most of them were operated by water pressure . The trick vessels are unimportant in themselves; their significance for historians of engineering

528-496: A process known as dewatering. Current dewatering techniques employ either centrifuges, geotube containers, large textile based filters or polymer flocculant /congealant based apparatus. In many projects, slurry dewatering is performed in large inland settling pits, although this is becoming less and less common as mechanical dewatering techniques continue to improve. Similarly, many groups (most notable in east Asia) are performing research towards utilizing dewatered sediments for

594-411: A shipping channel through coral reefs . A bucket dredger is equipped with a bucket dredge, which is a device that picks up sediment by mechanical means, often with many circulating buckets attached to a wheel or chain . A grab dredger picks up seabed material with a clam shell bucket , which hangs from an onboard crane or a crane barge , or is carried by a hydraulic arm, or is mounted like on

660-609: A similar conclusion in 851–852. They observed the longitude of Regulus from their house on a bridge in Baghdad in 840–841, 847–848, and 850–851, and made observations of Sirius , Al-Bīrūnī used data about the Moon obtained by the Banū Mūsā in his astrological calculations. The Banū Mūsā were some of the earliest scholars to adopt Greek mathematics . They differed from the Greeks in their approaches to

726-481: Is a stub . You can help Misplaced Pages by expanding it . Dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features ; reshaping land and water features to alter drainage , navigability , and commercial use; constructing dams , dikes , and other controls for streams and shorelines; and recovering valuable mineral deposits or marine life having commercial value. In all but

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792-515: Is a bar or blade which is pulled over the seabed behind any suitable ship or boat. It has an effect similar to that of a bulldozer on land. The chain-operated steam dredger Bertha , built in 1844 to a design by Brunel and as of 2009 was the oldest operational steam vessel in Britain, was of this type. This is an early type of dredger which was formerly used in shallow water in the Netherlands. It

858-1070: Is forbidden unless authorized by a permit issued by the Army Corps of Engineers . Due to potential environmental impacts, dredging is often restricted to licensed areas, with vessel activity monitored closely using automatic GPS systems. According to a Rabobank outlook report in 2013, the largest dredging companies in the world are in order of size, based on dredging sales in 2012 Notable dredging companies in North America Notable dredging companies in South Asia Ban%C5%AB M%C5%ABs%C4%81 brothers The three brothers Abū Jaʿfar, Muḥammad ibn Mūsā ibn Shākir (before 803 – February 873); Abū al-Qāsim, Aḥmad ibn Mūsā ibn Shākir (d. 9th century) and Al-Ḥasan ibn Mūsā ibn Shākir (d. 9th century), were Persian scholars who lived and worked in Baghdad . They are collectively known as

924-424: Is mainly used in harbours and other shallow water. Excavator dredge attachments The excavator dredge attachment uses the characteristics of cutter-suction dredgers, consisting of cutter heads and a suction pump for transferring material. These hydraulic attachments mount onto the boom arm of an excavator allowing an operator to maneuver the attachment along the shoreline and in shallow water for dredging. This

990-523: Is responsible for the motion of the heavens, and instead considered that the Sun, the Moon, the planets, and the stars all moved of their own volition. The other astronomical or astrological works by the Banū Mūsā are: The calculation by Moḥammad and Aḥmad of the Sun’s mean motion in a year agreed with the result obtained by al-Bīrūnī—that a solar year was 365 days and less than 6 hours long. Aḥmad independently reached

1056-442: Is the means by which they were developed. Many of Ahmad's ideas were obtained from Greek texts such as Philo of Byzantium 's Pneumatics (3rd century BCE) and Hero of Alexandria 's Pneumatics (written in the 1st century CE). However, some of the devices, particularly when involving small variations in fluid pressure , and automatic control components such as valves, were developed by the Banū Mūsā. The most important copies of

1122-410: Is usually sucked up by a wear-resistant centrifugal pump and discharged either through a pipe line or to a barge. Cutter-suction dredgers are most often used in geological areas consisting of hard surface materials (for example gravel deposits or surface bedrock) where a standard suction dredger would be ineffective. They can, if sufficiently powerful, be used instead of underwater blasting. As of 2024,

1188-479: The Leiv Eriksson are: 46,000 cubic metre hopper and a design dredging depth of 155 m. Next largest is HAM 318 ( Van Oord ) with its 37,293 cubic metre hopper and a maximum dredging depth of 101 m. A cutter-suction dredger's (CSD) suction tube has a cutting mechanism at the suction inlet. The cutting mechanism loosens the bed material and transports it to the suction mouth. The dredged material

1254-519: The 1947 Fort Lauderdale Hurricane and the population explosion in Greater Miami and subsequent urban sprawl following World War II . 25°41′31″N 80°18′42″W  /  25.69194°N 80.31167°W  / 25.69194; -80.31167 This Miami-Dade County, Florida location article is a stub . You can help Misplaced Pages by expanding it . This article related to a river in Florida

1320-560: The Abbasid caliph Harun al-Rashid who was staying in Merv . Al-Maʾmūn, who became caliph in 813, employed Musa as an astronomer. According to one story, al Ma’mun saw the Greek polymath Aristotle in a dream telling him about the importance of natural philosophy , which resulted in al-Ma’mun supporting the work then being done by scholars, during what has been called by some historians of science as

1386-663: The Banū Mūsā ( Arabic : بنو موسی , "Sons of Mūsā (or Moses)"). The Banū Mūsā were the sons of Mūsā ibn Shākir , who was a well-known Astronomer of al-Ma'mun , a son of the Abbasid caliph Harun al-Rashid . After their father's death, the brothers received an education under al-Ma'mun’s direction, and were enrolled at the House of Wisdom in Baghdad. There they undertook the translation of ancient Greek works acquired from Byzantium , which they used to develop their own technological, mathematical and astronomical ideas. They were some of

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1452-508: The Islamic Golden Age . After their father's death, the three orphaned children were cared for at the court of al-Maʾmūn, who made the senior Baghdad official Ishaq ibn Ibrahim al-Mus'abi their guardian. Al-Ma’mun recognized their abilities, and enrolled them in the House of Wisdom , an institution created by him as a centre for collecting, translating and studying books from other lands. In Baghdad, where they apparently lived for

1518-477: The Nile were channelled and wharfs built at the time of the pyramids (4000 BC), there was extensive harbour building in the eastern Mediterranean from 1000 BC and the disturbed sediment layers gives evidence of dredging. At Marseille , dredging phases are recorded from the third century BC onwards, the most extensive during the first century AD. The remains of three dredging boats have been unearthed; they were abandoned at

1584-645: The 13th century. A Latin translation by the 12th century Italian astrologer Gerard of Cremona appeared entitled Liber trium fratrum de geometria and Verba filiorum Moysi filii Sekir . This treatise on geometry, which is similar to Archimedes's On the measurement of the circle  and  On the sphere and the cylinder . was used extensively in the Middle Ages, and was quoted by authors such as Thābit ibn Qurra, Ibn al-Haytham , Leonardo Fibonacci (in his Practica geometriae ), Jordanus de Nemore , and Roger Bacon . It includes theorems not known to

1650-515: The Earth of 24,000 miles (39,000 km). Under the patronage of the caliphs that followed al Ma’mun— al-Mu'tasim , al-Wathiq , and al-Mutawakkil —the brothers continued to acquire great wealth and become influential in court. They used much of their wealth to collect the works of ancient writers, a practise that was later copied by other scholars at the House of Wisdom. The brothers were very active during

1716-503: The Greeks for the Earth's circumference . They first measured the altitude of the Pole Star , and then, using pegs and a rope as they moved north, stopped again when the altitude of the star changed by one degree. They repeated the same measurement, this time travelling southwards. The process was repeated at al-Kufa. From their measurements, the brothers obtained a value for the circumference of

1782-570: The Greeks. The book was re-published in Latin with an English translation by the American historian Marshall Clagett , who has also summarized how the work influenced mathematicians during the Middle Ages . The other known mathematical works by the Banū Mūsā were: Kitab al-Hiyal al-Naficah (" The Book of Ingenious Devices "), the only surviving work by Aḥmad, describes 100 inventions, 25 of which had

1848-780: The Mathematical Proof by Geometry that there Is not a Ninth Sphere Outside the Sphere of the Fixed Stars") is a lost book, reportedly written by Ahmed. Also referred to as the Kitāb al-Hay’a ("Book of Astronomy"), or the Kitāb Ḥarakāt al-falak al-ūlā ("Book on the First Motion of the Celestial Sphere"), the work analysed the Ptolemy 's geocentric model of the cosmos, in which a ninth sphere

1914-520: The beds of streams. During the renaissance Leonardo da Vinci drew a design for a drag dredger. Dredging machines have been used during the construction of the Suez Canal from the late 1800s to present day expansions and maintenance. The completion of the Panama Canal in 1914, the most expensive U.S. engineering project at the time, relied extensively on dredging. These operate by sucking through

1980-550: The bottom of the harbour during the first and second centuries AD. The Banu Musa brothers during the Muslim Golden Age in while working at the Bayt-Al-Hikmah (house of wisdom) in Baghdad, designed an original invention in their book named ‘ Book of Ingenious Devices ’, a grab machine that does not appear in any earlier Greek works. The grab they described was used to extract objects from underwater, and recover objects from

2046-446: The caliphs for different civil engineering projects, including their involvement in the building of the city of al-D̲j̲aʿfariyya for al-Mutawakki, led to them becoming involved in court politics. In 860, the Banū Mūsā and Mutawakkil’s architects were involved in obtaining land for a new city. The caliph’s advisor suggested that Muhammed and Ahmad bin Musa should be forced to contribute towards

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2112-428: The city of Samarra . To calculate the difference in latitude between Samarra and Nishapur , they organized simultaneous observations of a lunar eclipse . Whilst working for al-Ma’mun, the Banū Mūsā travelled to a desert near Sanjar , in northern Mesopotamia , with the aim of measuring the length of a degree of latitude along a meridian , and from that verifying a value of 25,000 miles (40,000 km) obtained by

2178-454: The concepts of area and circumference , giving them numerical values rather than considering them in terms of ratios . The most important of the works produced by the Banū Mūsā was the Kitāb maʻrifat masāḥat al-ashkāl al-basīṭah wa-al-kurīyah (" Book on the Measurement of Plane and Spherical Figures "), of which a commentary was made by the persian polymath Naṣīr al-Dīn al-Ṭūsī in

2244-605: The construction industry. Dredging is a four-part process: loosening the material, bringing the material to the surface (together extraction), transportation and disposal. The extract can be disposed of locally or transported by barge or in a liquid suspension in pipelines. Disposal can be to infill sites, or the material can be used constructively to replenish eroded sand that has been lost to coastal erosion , or constructively create sea-walls, building land or whole new landforms such as viable islands in coral atolls . Ancient authors refer to harbour dredging. The seven arms of

2310-492: The dredge continues its work. A number of vessels, notably in the UK and NW Europe de-water the hopper to dry the cargo to enable it to be discharged onto a quayside 'dry'. This is achieved principally using self discharge bucket wheel, drag scraper or excavator via conveyor systems. When contaminated (toxic) sediments are to be removed, or large volume inland disposal sites are unavailable, dredge slurries are reduced to dry solids via

2376-482: The dredge operator position the dredger and monitor the current dredge level. The monitoring software often uses Real Time Kinematic satellite navigation to accurately record where the machine has been operating and to what depth the machine has dredged to. In a "hopper dredger", the dredged materials end up in a large onboard hold called a "hopper." A suction hopper dredger is usually used for maintenance dredging. A hopper dredge usually has doors in its bottom to empty

2442-425: The dredged materials, but some dredges empty their hoppers by splitting the two-halves of their hulls on large hydraulic hinges. Either way, as the vessel dredges, excess water in the dredged materials is spilled off as the heavier solids settle to the bottom of the hopper. This excess water is returned to the sea to reduce weight and increase the amount of solid material (or slurry) that can be carried in one load. When

2508-474: The earliest scholars to adopt Greek mathematics , but innovative in their approach to the concepts of area and circumference by expressing them using numerical values instead of ratios . They made geodesic measurements to determine the length of a degree of latitude , and so obtained a relatively accurate value for the circumference of the Earth . The Banū Mūsā wrote almost 20 books, all but three of which are now lost. The most important of all their works

2574-543: The environment, including the following: The nature of dredging operations and possible environmental impacts requires that the activity often be closely regulated and requires comprehensive regional environmental impact assessments alongside continuous monitoring. For example, in the U.S., the Clean Water Act requires that any discharge of dredged or fill materials into "waters of the United States," including wetlands,

2640-406: The expense of a new palace nearby. The peak of Muhammad's political activity came towards the end of his life, when Turkish commanders were starting to take control of the state. After the death of al-Mutawakkil, Muhammad helped al-Mustaʿīn to become nominated as caliph. Denied the throne, Al-Mustaʿīn's brother besieged Baghdad, and Muhammad was sent to estimate the size of the attacking army. After

2706-519: The form of a scoop made of chain mesh, and are towed by a fishing boat . Clam-specific dredges can utilize hydraulic injection to target deeper into the sand. Dredging can be destructive to the seabed and some scallop dredging has been replaced by collecting via scuba diving . As of June 2018, the largest dredger in Asia is MV  Tian Kun Hao , a 140-metre (460 ft) long dredger constructed in China, with

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2772-447: The hopper is filled with slurry , the dredger stops dredging and goes to a dump site and empties its hopper. Some hopper dredges are designed so they can also be emptied from above using pumps if dump sites are unavailable or if the dredge material is contaminated. Sometimes the slurry of dredgings and water is pumped straight into pipes which deposit it on nearby land. These pipes are also commonly known as dredge hoses , too. There are

2838-469: The material could well suit the building industry, or could be used for beach nourishment. Dredging can disturb aquatic ecosystems , often with adverse impacts. In addition, dredge spoils may contain toxic chemicals that may have an adverse effect on the disposal area; furthermore, the process of dredging often dislodges chemicals residing in benthic substrates and injects them into the water column . Dredging can have numerous significant impacts on

2904-460: The material through doors in the hull or pumps the material out of the hoppers. Some dredges also self-offload using drag buckets and conveyors. As of 2008 the largest trailing suction hopper dredgers in the world were Jan De Nul 's Cristobal Colon (launched 4 July 2008 ) and her sister ship Leiv Eriksson (launched 4 September 2009 ). Main design specifications for the Cristobal Colon and

2970-525: The mathematician and translator Hunayn ibn Ishaq , who became a close friend of one of the brothers, Muhammad. Of the translators, three were paid about 500 dinars a month. None of the brothers were medically trained, and relied upon Ishaq bin Hunayn and Thabit bin Qurra to translate Greek medical works. They exchanged ideas with other experts, including the astrologer Abu Ma'shar al-Balkhi , with whom Muhammed

3036-400: The modern period. One of those inventions includes an automatic flute player that may have been the first programmable machine or computer. Moḥammad, Aḥmad, and Ḥasan were the three sons of Mūsā ibn Shākir . They are always listed in sources in what is assumed by scholars to be their order of seniority. Musa was A Persian from Khorasan and a well-known Astronomer, al-Ma'mun , a son of

3102-462: The most powerful cutter-suction dredger in the world is DEME 's Spartacus , which entered service in 2021. The auger dredge system functions like a cutter suction dredger, but the cutting tool is a rotating Archimedean screw set at right angles to the suction pipe. Mud Cat invented the auger dredge in the 1970s. These use the Venturi effect of a concentrated high-speed stream of water to pull

3168-426: The nearby water, together with bed material, into a pipe. An airlift is a type of small suction dredge. It is sometimes used like other dredges. At other times, an airlift is handheld underwater by a diver . It works by blowing air into the pipe, and that air, being lighter than water, rises inside the pipe, dragging water with it. Some bucket dredgers and grab dredgers are powerful enough to rip out coral to make

3234-667: The production of concretes and construction block, although the high organic content (in many cases) of this material is a hindrance toward such ends. The proper management of contaminated sediments is a modern-day issue of significant concern. Because of a variety of maintenance activities, thousands of tonnes of contaminated sediment are dredged worldwide from commercial ports and other aquatic areas at high level of industrialization. Dredged material can be reused after appropriate decontamination. A variety of processes has been proposed and tested at different scales of application ( technologies for environmental remediation ). Once decontaminated,

3300-439: The reign of al-Mutawakkil, who was interested in mechanics, and asked the Banū Mūsā to write on this subject. A son of al-Mu'tasim was educated by Ahmad, but the brothers' relations with the caliph are otherwise unknown. When close to death, al-Mu'tasim's successor al-Wathiq called together his astrologers, including Muhammed, who erroneously pronounced that the caliph would live for another 50 years. The Banū Mūsā's employment by

3366-572: The rest of their lives, the three brothers studied geometry , mechanics , music, mathematics and astronomy , trained by a senior court astrologer , Yaḥyā bin Abī Manṣūr . The Banū Mūsā assisted al-Ma'mun's in his obsession to obtain and translate works from Greek into Arabic . They sent for Greek texts from the Byzantines , or travelled themselves to Byzantium to acquire them. During their working lives they used their wealth and energy towards

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3432-476: The seabed to bring the sediment in suspension, which then becomes a turbidity current , which flows away down slope, is moved by a second burst of water from the WID or is carried away in natural currents. Water injection results in a lot of sediment in the water which makes measurement with most hydrographic equipment (for instance: singlebeam echosounders) difficult. These dredgers use a chamber with inlets, out of which

3498-461: The seabed with its hull out of the water. Some forms can go on land. Some of these are land-type backhoe excavators whose wheels are on long hinged legs so it can drive into shallow water and keep its cab out of water. Some of these may not have a floatable hull and, if so, cannot work in deep water. Oliver Evans (1755–1819) in 1804 invented the Oruktor Amphibolos, an amphibious dredger which

3564-628: The sediment. These environmental impacts can reduce marine wildlife populations in some cases, contaminate sources of drinking water and interrupt economic activities such as fishing. Dredging is excavation carried out underwater or partially underwater, in shallow waters or ocean waters . It keeps waterways and ports navigable, and assists coastal protection, land reclamation and coastal redevelopment, by gathering up bottom sediments and transporting it elsewhere. Dredging can be done to recover materials of commercial value; these may be high value minerals or sediments such as sand and gravel that are used by

3630-452: The siege, he was sent to find out the terms for al-Mustaʿīn to abdicate. It was during the reigns of al-Wathiq and al-Mutawakkil that internal rivalries arose between the scholars there. The Banū Mūsā became enemies of al-Kindi, and assisted in his persecution by al-Mutawakkil. They criticized and ridiculed his treatise on the astrolabe , and caused al-Mutawakkil to have him beaten, removed from court, and his library confiscated. The library

3696-410: The translation of these works. On his way home to Baghdad from Byzantium, Muhammad met and recruited Thābit ibn Qurra , a money changer from Harran . Thābit went on to make important discoveries in algebra, geometry, and astronomy. Under the direction of al-Ma'mun, the Banū Mūsā worked with the most talented men available, including al-Khwarizmi , al-Kindi , Al-Ḥajjāj ibn Yūsuf ibn Maṭar , and

3762-427: The water is pumped with the inlets closed. It is usually suspended from a crane on land or from a small pontoon or barge. Its effectiveness depends on depth pressure. A snagboat is designed to remove big debris such as dead trees and parts of trees from North America waterways. Some of these are any of the above types of dredger, which can operate normally, or by extending legs, also known as spuds, so it stands on

3828-448: The work to Fargftani. The caliph discovered that, due to an engineering error, once built, the water in the canal would drain away. He decreed that the brothers would be crucified beside the canal if this happened. Sanad bin Ah', who was the caliph's consultant engineer , agreed to proclaim—four months before the truth was to be revealed, and knowing that astrologers had predicted that the caliph

3894-681: The world are currently the Vitruvius, the Mimar Sinan, Postnik Yakovlev (Jan De Nul), the Samson (DEME), the Simson and the Goliath (Van Oord). They featured barge -mounted excavators. Small backhoe dredgers can be track-mounted and work from the bank of ditches. A backhoe dredger is equipped with a half-open shell. The shell is filled moving towards the machine. Usually dredged material is loaded in barges. This machine

3960-446: Was America's first steam-powered road vehicle. These are usually used to recover useful materials from the seabed. Many of them travel on continuous track . A unique variant is intended to walk on legs on the seabed. Fishing dredges are used to collect various species of clams , scallops , oysters or mussels from the seabed. Some dredges are also designed to catch crabs, sea urchins, sea cucumbers, and conch. These dredges have

4026-731: Was a treatise on geometry , Kitāb Maʿrifah masāḥat al-ashkāl al-basīṭah wa-al-kuriyyah (" Book on the Measurement of Plane and Spherical Figures "), which was used extensively by medieval mathematicians. Their most famous extant work (of which the oldest and most reliable copy is in the Topkapi Sarayi in Istanbul ) is Kitab al-Hiyal al-Naficah (" Book of Ingenious Devices "). It describes 100 inventions, many of which were pouring vessels, intended to entertain party guests. Some of their innovations, such as those that involved fluid pressure variations and valves , remained unsurpassed until

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4092-464: Was a flat-bottomed boat with spikes sticking out of its bottom. As tide current pulled the boat, the spikes scraped seabed material loose, and the tide current washed the material away, hopefully to deeper water. Krabbelaar is the Dutch word for "scratcher". A water injection dredger uses a small jet to inject water under low pressure (to prevent the sediment from exploding into the surrounding waters) into

4158-700: Was an expert on mathematics and astronomy, Ahmad excelled in technology, and al-Hasan on mathematics. Muhammed knew the works of both Euclid and Ptolemy, and was considered by contemporaries to be an expert mathematician, astronomer, and philosopher . All but three of the books attributed by scholars to the Banū Mūsā are now lost. Many of the lost works are named in the Book of Ingenious Devices , their most famous work. The Banū Mūsā are known to have made many astronomical observations in Baghdad. Kitāb bayyana fīhī bi-ṭarīq taʿlīmī wa-madhhab handasī annahū laysa fī khārij kurat al-kawākib al-thābitah kurah tāsiʿah ("Book on

4224-410: Was close to death—that no error had been made. The brothers were saved from execution when the caliph was assassinated shortly afterwards. Of the three brothers, only the year that Mohammed died—January 873—is known. The Banū Mūsā wrote almost 20 books. Moḥammad was the most productive of the brothers; of his many works, one still exists. They worked together as well as separately: Jafar Muhammad

4290-462: Was in continuous contact. The brothers are likely to have used portable instruments such as armillary spheres or dials when making their observations, which were recorded from around 847 to 869. From their Baghdad home, they observed stars in the constellation Ursa Major In 847–848, and measured the maximum and minimum altitudes of the Sun in 868–869. They also observed the September equinox in

4356-475: Was returned back to him at a later date with the help of the Persian Jewish scholar Sanad ibn Ali , who insisted the library was returned as a condition to him assisting the Banū Mūsā over his judgement concerning the construction of a canal for the city of al-Ja’fariyya. Shortly before his death, Mutawakkil gave the Banū Mūsā overall responsibility for building the al-Ja’fariyya canal; they in turn delegated

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