You Could Look It Up (11 page)

The
Geographike hyphegesis
is in eight books. The first serves as an introduction, and it features a substantial critique of the maps of one of Ptolemy's predecessors, Marinos of Tyre. We know nothing about Marinos beyond what we can gather from Ptolemy's text, which called him “the latest [author] in our time to have undertaken this subject,”
5
so he probably lived not long before Ptolemy himself. Ptolemy criticized his shortcomings, such as his inaccurate estimates of the size of the earth and his technical problems with his understanding of the projection of latitude and longitude onto the spherical surface of the earth. But still he borrowed from Marinos at length.

With book 2, Ptolemy introduced the coordinates that occupy most of his work, starting in the far west: Ireland, Britain, Hispania, Gaul, Germany, and the upper Danube. Book 3 covers the Italian and Greek peninsulas and the islands around them, as well as the lower Danube. Book 4 crosses the Mediterranean into northern Africa, and Ptolemy progressed from west to east, from Egypt to Ethiopia. Book 5 starts in Asia Minor—modern Turkey—and covers Armenia, Cyprus, Syria, and most of the Middle East. Book 6 is devoted to the regions that had once formed the Persian Empire. Book 7 is devoted to the Indian subcontinent, and included a description of a complete world map. Book 8—which some critics believe may include material not written by Ptolemy—surveys more than two dozen regional maps.
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A typical section shows Ptolemy's method:

In Hispania, known by the Greeks as Iberia, there are three provinces, Baetica and Lusitania and Tarraconensis. And the west and north borders of Baetica are determined by Lusitania and part of Tarraconensis respectively, a description of which is made as follows:

Ptolemy measured his coordinates in degrees, with 360 to a circle, as we do today; he also provided fractions of a degree to approximate minutes: 4
⅓
is 4 degrees 20 minutes. Coordinates, of course, have meaning only in relation to some known point. The equator provided him with a natural reference for latitude. The prime meridian is nothing natural, only a social convention, and at that time none was recognized. Greenwich was not used even by British cartographers until the late eighteenth century, and it was not adopted internationally until 1884.
Ptolemy picked the “Fortunate Isles,” probably what we call the Canary Islands, for his starting point. There are of course plenty of inaccuracies in his reports; he was least reliable in reporting the east–west dimensions of the Mediterranean and in believing that some sort of land bridge connected Africa to China. But his was the most complete and most accurate picture of the world that could be had at the time.

With the collapse of the Western Roman Empire in the fifth century, the European field of vision narrowed considerably, and cartography suffered. Not so in the Muslim world: at the end of the first millennium, Islam's maps were more accurate than anything Europe had to offer. And in Muslim hands, Ptolemy's
Geography
took on new prominence, thanks to one of the most learned figures in the world. All we have are
probably
s for most of the basic facts of his life: he was probably born around the year 780 in or near Baghdad, was probably of Persian origin, and was probably based at Baghdad's Bayt al-Hikma, or House of Wisdom, during the Abbasid Caliphate. We can be certain, though, that Muhammad ibn Musa al-Khwarizmi was a polymath. He gave us two words whose importance has only grown in the centuries since he lived: the title of his book
Kitab al-muktasar fi hisab al-jabr wal-muqabala
, or
The Concise Book on Calculation by Restoration and Compensation
, is the source of the word
algebra
(
al-jabr
means “compensation”), and his name, al-Khwarizmi, once Latinized and then passed around through the modern languages, gave us the
algorithm
. Every high-tech computer calculation pays tribute to the ninth-century Islamic genius.

Al-Khwarizmi's
Kitab surat al-Ard
(
Book on the Appearance of the Earth
) is the expression of his lifelong interest in geography. It is the hardest of his books to date; many scholars guess 816–17
C.E.
, but some place it as late as 833
C.E.
Al-Khwarizmi borrowed many of Ptolemy's coordinates and often used his reference points, though he also reorganized the material and checked the facts against the latest and best geographical information available to him. For nearly a millennium and a half, Ptolemy's
Geography
—in its Greek, Latin, and Arabic versions, updated by generations of cartographers in Europe and the Middle East—was the most important set of maps in the world, providing “the strongest link the chain between the knowledge of mapping in the ancient and early modern worlds.”
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As al-Khwarizmi proved, during Europe's so-called Dark Ages the serious intellectual work was going on far away. But that is not to say nothing was going on in Europe between the fall of the Roman Empire and the Renaissance. Cartography was too important to be neglected entirely. Even England—part of a small, cold, rainy island off the northwest coast of Europe, marginally significant in Western Europe, utterly irrelevant in the rest of the world—created a geographical survey in the eleventh century that would be unequaled in its extent for another eight hundred years.

Guillaume II, Duc de Normandie, turned his eyes across the Channel to the land of the Angles and the Saxons, and in 1066 he led an invasion that would prove to be one of the most consequential in Europe's long history. After leading his forces to a town on England's southern coast, Hastings, and defeating Harold Godwinson, Guillaume earned a new title: no longer merely the duke of Normandy, he was William the Conqueror. Anglo-Saxon England now had French-speaking rulers.

Nineteen years after the Norman Invasion, William was concerned about security. The Danes had their eyes on his country, and he needed money for soldiers to keep the Vikings away. The obvious source of revenue was taxation, but William had no idea how much his new country was worth. The Anglo-Saxon kings had neither the interest nor the administrative structure to compute the population and wealth of every village, but William was determined to find out. During the Christmas celebrations in 1085, therefore, he ordered a comprehensive survey of England in order to establish the basis for taxing his people. It was also a means of asserting his control over his still-new country, and of determining who among his subjects might be expected to fight on his side.

William charged seven or eight panels of commissioners with performing the great survey, and each was assigned a set of counties. These hundreds of commissioners and aides then fanned out across the country collecting information: the name of every hamlet, village, town, and city; the population; the number of people at each social rank and of each profession; the value of the buildings; even the amount of
livestock. The
Anglo-Saxon Chronicle
, the most important year-by-year account of early English history, recorded the process:

He had a record made of how much land his archbishops had, and his bishops and his abbots and his earls—and though I relate it at too great length—what or how much everybody had who was occupying land in England, in land or in cattle, and how much money it was worth. So very narrowly did he have it investigated that there was no single virgate of land, nor indeed (it is a shame to relate but it seemed no shame to him to do) one ox nor one cow nor one pig which there was left out, and not put down in his record.
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A book called the
Inquisitio comitatus Cantabrigensis
, or
Investigation of the County of Cambridge
, survives as a working draft of the material for Cambridgeshire, and it reveals how the commissioners proceeded, collecting information first by shires, then by hundreds, then by villages. Some facts came from written records, but most from in-person inspections and interviews. In each county town they organized sworn inquests of sheriffs, barons, and other representatives of each village, giving them questionnaires demanding precise answers to specific questions. Much of the public was unhappy, not yet reconciled to a French-speaking king whose agents were snooping around. Everyone knew this was a means of increasing tax revenues, and property owners tried to play down the value of their property, pointing out problems to the agents. To verify the accuracy of what they were told, the commissioners ordered special sittings of the county courts all over the country, where their sources were to give their testimony and jurors—half English, half French—worked to keep people honest.

When the commissioners had collected all the information, they reorganized it to account for the new feudal arrangements that followed the conquest of 1066, emphasizing the role of the barons in order to change the strictly geographical organization into something more informed by social hierarchies. For each county, the commissioners produced a list of landholders, from the king at the top to the poorest tenant at the bottom. They described all their fiefs, with the names of holders of manors from both 1066, right before William took over the
country, and 1085, when the survey began. They provided the dimensions of plots of land, the number of workers on each estate, and the value of the land:

LAND OF THE BP. OF COUTANCE

The Bp. of Coutance holds half a hide in F
ILVNGELEI
, and Lewin of him. The arable employs ii ploughs. One is in the demesne; with ii bondmen. There are v villeins, and ii borders; they have i plough. There are ii acres of meadow. Wood ii furlongs long, and one furling broad. It was worth x
s.
Now xxx
s.
Alwin held it freely.

The collection of information took a total of eight months—astonishingly quick, considering how much they had to accomplish and how slowly both people and information moved—after which a second team of commissioners checked their work. Several monks were then set to work transcribing 2 million words of text.

The result was
The Description of England
, better known as
The Domesday Book
—a name that comes from the assumption that what appeared there was as authoritative as what God had written in the book of judgment for the end of time. In fact it was two books, with
Great Domesday
covering most of the country and
Little Domesday
giving the raw data on Essex, Norfolk, and Suffolk. Even in the combined work there were omissions.
Domesday
did not cover all of the north of England. London and Winchester were omitted altogether, though there are gaps in the manuscript, suggesting that there were plans to include other information at some point. Even so, the work occupies more than sixteen hundred large pages of parchment, collecting the names of 13,418 places and 109,230 “villeins” out of a population of around 2 million. It established a value for all the surveyed English land of £73,000.
The Domesday Book
served William well: with his new comprehensive reference book in hand, he determined his tax policies. He never got to make much use of the information, though, for he died in 1087, some say from illness and others from injury. But he left a powerful administrative machine in place for his son, William Rufus, and for a long line of Norman kings of England.