Editing Nilometer (section)

=== Roda Island ===
The first nilometer on [[Roda Island]] was constructed by Usama bin Zayd bin Adl before [[Jumada al-Thani|Jumada II]], 96 [[Hijri year|AH]] (February 715), during the reign of the [[Umayyad Caliphate|Umayyad]] caliph [[Al-Walid I|al-Walid]]. The 14th-century Arabic historian [[Al-Maqrizi|Maqrīzī]] claims that the construction cost 24,000 [[Dirham|dirhams]]. During the reign of [[Sulayman ibn Abd al-Malik]], Usama wrote to the caliph informing him of the dilapidated state of the nilometer. He received a reply ordering him to construct a new one, which he did in 97 AH (5 September 715—24 August 716).<ref name=":1">{{Cite book |last=Creswell |first=K. A. C. |title=Early Muslim Architecture: Umayyads, Early 'Abbasids and Tulunids: II: Early 'Abbasids, Umayyads of Cordova, Aghlabids, Tulunids and Samanids. A.D. 751 - 905, Part 2 |date=1 January 1978 |publisher=[[Clarendon Press]] |language=English}}</ref>{{Rp|page=296}} [[Yaqut al-Hamawi]], writing in the 12th–13th centuries, claims that in the beginning of year 247 AH (March 861), during [[Yazid ibn Abdallah al-Hulwani|Yazid ibn Abd Allah al-Turki's]] governorship of Egypt, the Abbasid caliph [[al-Mutawakkil]] had the 'new' nilometer constructed and ordered that the privilege of measuring the river 'be taken away from the Christians.' The governor then appointed a man from [[Basra]] named Abu'r-Raddad who had emigrated to Egypt and taught [[hadith]]. He died in 266 AH (879/80), with Yaqut claiming 'the supervision of the Nilometer has remained in the hands of his descendants until the present day' (which would have been around 1225 for the author).<ref name=":1" />{{Rp|page=297}} [[Ibn Khallikan]], a 13th-century historian, gives a different account of this nilometer, recounting that a 'pious' [[muezzin]] in the old [[Amr ibn al-As Mosque|Mosque of Amr]] wished to carve inscriptions in various places of the nilometer. After consulting with Yazid ibn Abd Allah, [[Sulayman ibn Wahb]] and Hasan al-Khadim, the muezzin proposed to inscribe various [[Quran|Qu'ranic]] passages in the name of al-Mutawakkil. Sulayman ibn Wahb then wrote to the caliph, who replied in writing to choose verses of the Qu'ran 'most appropriate' to the nilometer and to inscribe the caliph's name.<ref name=":1" />{{Rp|pages=297-298}}

Ibn Khallikan writes that the architect of the nilometer was Ahmad ibn Muhammad al-Hasib. Abu Ja'far al-Katib and [[Ibn Abi Usaybi'a]] mention that [[Al-Farghani|Ahmad ibn Kathir al-Farghani]] was sent to [[Fustat]] by al-Mutawakkil to supervise the construction. [[Abu al-Mahasin Yusuf al-Fasi|Abu al-Mahasin Yusuf]] (d. 1604) makes the same statement but calls him Muhammad ibn Kathir al-Farghani (full name: Abu'l-Abbas Ahmad ibn Muhammad ibn Kathir al-Farghani). For this reason, [[Gaston Wiet]] and [[K. A. C. Creswell|Creswell]] argue that the al-Farghani and al-Hasib are the same person.<ref name=":1" />{{Rp|page=303}}

In 872–3 (259 AH), [[Ahmad ibn Tulun]], the autonomous ruler of Egypt, would also have the nilometer restored. Al-Mutawakkil's name was removed from the [[Kufic]] inscription of the nilometer.<ref>{{Cite book |last=yeomans |first=richard |url=https://books.google.com/books?id=5NFPAAAAMAAJ |title=the art and architecture of islamic cairo |date=2006 |publisher=Garnet Pub. Limited |isbn=978-1-85964-154-5 |pages=30 |language=en}}</ref> K. A. C. Creswell states that the main inscription of the nilometer was probably tampered with by Ibn Tulun, saying "there can be little doubt that it was he who removed the name of the [[List of Abbasid caliphs|Abbasid Khalif]]." Ibn Tulun would however refrain from substituting his own name, with Creswell claiming as he did not feel sufficiently secure to do so. The first [[Tulunids|Tulunid]] [[Emir]] during 872-873 would spend 1,000 dinars on works carried out on the nilometer.<ref name=":1" />{{Rp|pages=298-299}} Consequently, according to Abdul Rofik Bruno, the Nile's irrigation would be enhanced, and agricultural output increased.<ref>{{Cite journal |last1=A |first1=Muhammad Esa Prasastia |last2=Rofiq |first2=Abdul |date=2022 |title=Analysis of The Causes of The Disintegration of The Government of The Abbasiyah Dynasty (1000 M-1250 M) |url=https://www.academia.edu/97440998 |journal=Devotion: Journal of Community Service |volume=3 |issue=3 |page=241 |issn=2797-6068}}</ref>

[[Amr ibn al-As]] after the [[Arab conquest of Egypt|conquest of Egypt]] reported to the [[Umar|Caliph Umar]] that when the Nile rose to 14 cubits there was a sufficient harvest, 16 an abundant harvest, 17 being the most advantageous height of all, and that at 18, one-fourth of Egypt would be [[Flood|inundated]] and usually be followed by plague. The Baghdad doctor, [[Abd al-Latif al-Baghdadi]] who traveled Egypt between 1192-1201 would also relate similar measurements. In the exceedingly low water levels of 1201 and 1202, the nilometer remained dry. In 1201, the year commenced with a rise in 2 cubits before rising an average 15¹⁶⁄₂₄ cubits. In 1202, the year began with 1½ cubits before rising to 15²³⁄₂₄ cubits.<ref>{{Cite journal |last=Ardagh |first=J. C. |date=1889 |title=Nilometers |url=https://www.jstor.org/stable/1800840 |journal=Proceedings of the Royal Geographical Society and Monthly Record of Geography |volume=11 |issue=1 |pages=28–38 |doi=10.2307/1800840 |jstor=1800840 |issn=0266-626X}}</ref>{{Rp|pages=31-32}} During the [[Abbasid Caliphate|Abbasid Period]], the nilometer was used to measure the river level and hence determine the [[Islamic taxes|rates of tax]] in Egypt.<ref>{{Cite web |date=2020-06-24 |title=Nilometer {{!}} IRCICA |url=https://www.islamicarchitecturalheritage.com/listings/nilometer |access-date=2024-04-15 |language=en-US}}</ref>

In 1937, efforts to drain and excavate the nilometer were begun by Kamil Bey Ghalib, the Under-Secretary of State for Public Works, employing a new method used by Rothpletz and Lienhard. In this method, the mud could be removed completely and the structure examined.<ref name=":1" />{{Rp|page=304}}

[[File:BarragemAssuão.jpg|thumb|Aerial view of Aswan Dam, Aswan Egypt]]