Al-Farghani's Mistake

While expanding the urban settlements along the Tigris, the 9th century Abbasid caliph al-Mutawakkil needed a canal to bring water to a new city, al-Jaʻfariyya (after the caliph's birth name). He gave two courtiers the job of finding an engineer to design and build the canal. Two brothers, Muhammad and Ahmad ibn Musa, went for the expertise of al-Farghani (c.800 - 870).

al-Farghani was one of the most famous astronomers in the Muslim world in the 9th century. He had written a summary of Ptolemy's Almagest called Elements of astronomy on the celestial motions with more accurate data. Columbus used al-Farghani's calculations on his voyages across the Atlantic. Under a previous Abbasid caliph, al-Ma'mun, al-Farghani and a team had used the curvature between two points to calculate the diameter of the Earth.

He had also worked as an engineer, and for al-Mutawakkil had successfully created the New Nilometer in Old Cairo (more on that later). So designing a canal was not outside of his abilities. There was something wrong with the construction, however. A miscalculation made the entrance to the canal too deep. Water entering it would have to be abnormally high to be able to enter the rest and flow to its destination.

al-Mutawakkil was angered, and sent someone to figure out how culpable the two brothers were for the error. The investigator was not keen to see Muhammad and Ahmad punished, so he kept delaying his report. In fact, he delayed it long enough that it became a non-issue after the assassination of al-Mutawakkil, saving the lives of the brothers.

al-Farghani was not known for making mistakes, and tomorrow we'll look at some of his accomplishments, as well as explain the New Nilometer, which is exactly what you think it might be based on the name. See you then.

Isabella's Reforms

Queen Isabella of Castile had a reputation for harshness when it came to crime and corruption. A Spanish writer and contemporary, Hernando del Pulgar (1436 - 1492), who became a councillor under Isabella, wrote a series of profiles of political figures and said of her:

She was very inclined to justice, so much so that she was reputed to follow more the path of rigor than that of mercy, and did so to remedy the great corruption of crimes that she found in the kingdom when she succeeded to the throne.*

Her predecessor, her half-brother Henry, was not a careful ruler: big on spending money, not big on maintaining the rule of law (hence the attempts by the nobles to dethrone him, using Isabella as their focus). Isabella had to get tough to restore order to Castile.

Her first reform was to co-opt La Santa Hermandad [The Holy Brotherhood]. The Brotherhood was a  feature of medieval Castile in which local armed men formed vigilante groups to maintain order in the communities. Isabella developed the Brotherhood into a local police force for each territory. They were paid by a new tax. The province of Galicia, known for highway robbery, had 1500 robbers driven out by a special force she sent with the task of cleaning up the area.

She also needed to restore the financial health of the country after Henry's excesses. Henry raised quick cash by selling property at low prices. The decision was made to purchase them back at the same low prices. Estates that Henry gave to others as gifts were taken back without remuneration. Some nobles who wished to regain the property could do so by paying a sum worthy of the property; this helped fill the treasury. She also reduced the number of mints making coins, which reduced rampant inflation.

Her final change was in the area of royal engagement. Isabella and Ferdinand spent some time each Friday allowing citizens to come to them with complaints. This was a form of contact with royalty and royal concern for the constituency previously unknown in Castile.

The year 1492 is, however, the year of events for which history usually thinks of her. Schoolchildren know her for her support of Columbus, and others condemn her for the Alhambra Decree, but she was the best ruler her country had seen in awhile.

*Pulgar, Crónica de los Reyes Católicos, trans. in David A. Boruchoff, "Historiography with License: Isabel, the Catholic Monarch, and the Kingdom of God," Isabel la Católica, Queen of Castile: Critical Essays (New York: Palgrave Macmillan, 2003), p. 242.

The Alhambra Decree

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There is an ethnic subdivision of Jews called Sephardic Jews. "Sephardic" comes from the Hebrew Sepharad, which referred to Hispania. More specifically, Sephardic Jews are those descended from Jews who lived in Spain in the 15th century. They migrated from the Middle East to The Iberian Peninsula/Sepharad/Hispania/Spain/ about 1000 CE.

Several weeks ago, the government of Spain passed a law that allows Sephardic Jews—no matter where they live, no matter in what country they currently have citizenship—to receive dual citizenship for the asking. Wherever they live now, they could receive Spanish citizenship without having to renounce citizenship elsewhere or even move to Spain. The reason, as explained in a recent  article in The Economist, is "righting an historical wrong."

The "historical wrong" was the Alhambra Decree.

The Alhambra Decree was issued on 31 March 1492 by the rulers of the majority of the Iberian Peninsula. (The peninsula comprised Portugal, Castile, Granada, Aragon, Navarre.) Isabella of Castile and Ferdinand II of Aragon ordered the expulsion of all Jews from their two kingdoms. The deadline for departure was 31 July 1492.*

Like England in an earlier century, a choice was offered: you may convert to Christianity and stay, or remain Jewish and leave, taking your possessions with you (except for gold, silver, currency, arms or horses). Refusing these choices meant immediate execution, and a non-Jew who aided a Jew through hiding him would suffer the loss of all property and privileges.

The Alhambra Decree, also known as the Edict of Expulsion, was formally revoked by Spain on 16 December 1968, as a result of reforms that came from the Second Vatican Council.

Where did the Jews go? What were their choices for a new homeland? There were a few options, some close by. But that's a topic for another day.

*Columbus departed on his maiden voyage across the Atlantic on 3 August, a mere four days after the Expulsion deadline.

The Ring of Fire vs. The Flood

15th century portrayal of Ptolemy's map

Prior to the Age of Exploration, human beings in the western hemisphere did not attempt to travel long distances by sea and discover distant lands.* This was partially because ships that could handle a very long voyage were not able to be built or provisioned easily for such a journey.** Another reason is that the world was "known" to be shaped so that long voyages were fruitless.

Eratosthenes (c.276-c.195 BCE) had established in the Classical Era the spherical nature of the Earth through simple and clear experimentation; no one disputed that. (His math on Earth's diameter was probably a little off: the unit of measurement he used probably gave him an Earth 4000 miles larger around than it is.) What was up for debate was the question of what existed "over the horizon."

Aristotle (384-322 BCE), upon whose scholarly shoulders the Middle Ages tried to stand, loved symmetry. It made sense to him that there were five zones (from the Greek word meaning "girdle") around the Earth. The extreme top and bottom were icy cold and uninhabitable. Just inside of them were the temperate zones where humans and animals lived—note: he believed both temperate zones were inhabited. In the middle it was so hot—and clearly, the further south you go from Greece and the Mediterranean the hotter it got—that it was uninhabitable. Pliny (23-79) said that this central zone was so hot that it was actually a ring of fire and was unlivable and impassable, so we would never be able to visit the people living in the southern hemisphere.

Wait, said Christianity. That can't be. The Flood covered the whole world, and when the waters receded, the Ark of Noah came to rest on Mt. Ararat in Turkey, from which all the animals strolled away and repopulated the world. If the ring of fire at the equator is impassable, how can there be animals living beyond it? Worse, if there are people living in the southern temperate region, how are we going to reach them with the Word of God?

Proving that classical scholars did not always agree, Ptolemy presented different problems in geography. His Geography was translated and made available to Western Europe in 1406. His map (depicted above in a 15th century version printed in Ulm) showed that all you had to do was sail far enough south to reach the southern lands in the world, but he also extended the bottom of Africa eastward, enclosing the Indian Ocean. This meant you could not sail to the Indian Ocean and therefore to India, but would forever have to use the Silk Road (and incidentally pay tolls at every border crossing, something sailors get to avoid).

The Age of Exploration changed all this. In 1473, Aristotle was proved wrong with a Portuguese ship exploring the west coast of Africa passed south of the Equator. In 1488, another Portuguese ship sailed around the Cape of Good Hope and reached the Indian Ocean. India and the east were accessible by ship after all, and the Portuguese quickly established those shipping routes.

Ptolemy's Geography was erroneous in another way. He estimated the Earth's circumference at thousands of miles smaller than Eratosthenes. Since no one cared to duplicate Eratosthenes' experiments and determine the distances involved, Ptolemy might have been taken as truth by some. His estimates of the size of a spherical Earth would put Asia thousands of miles closer to Europe by sailing west. With Portugal dominating southern routes to the East, was it Ptolemy's miscalculation that prompted Spain's Columbus to try a bold plan to establish a different and (he thought) shorter route?

*Perhaps some day we'll get to some of the rare cases of accidental discovery of previously unanticipated lands.
**I have been aboard replicas of Columbus' ships; they are frighteningly small considering the journey they made.