The Greek inheritance

Alexander and Ptolemy: 332-285 BC

Alexander the great decides that the small Egyptian port of Rhacotis is a natural base for future operations in the eastern Mediterranean. It is close to the delta of the mighty Nile, but far enough removed to avoid silting up; it has a protective island, Pharos, a little way offshore; and it is well placed for trade or warfare with the middle east. He builds a new suburb beside the old town (inhabited already for more than 1000 years) and calls old and new jointly after himself - Alexandria.

Under Ptolemy, Alexander's successor in Egypt, the new city begins a glittering career.

Ptolemy adds legitimacy to his rule in Egypt by acquiring Alexander's body. He intercepts the embalmed corpse on its way to burial, brings it to Egypt and places it in a golden coffin in Alexandria.

It will remain one of the famous sights of the town for many years, until probably destroyed in riots in the 3rd century AD.

Alexandria as a capital city: from about 320 BC

Ptolemy recognizes in Alexandria the natural advantages which had attracted Alexander to the site. He makes it his capital and begins to transform it into one of the greatest centres of learning in the Greek world.

He founds here in Egypt what is in effect a university, though the word he uses for it is 'museum', home of the Muses. Mathematicians of the stature of Euclid, Archimedes and Eratosthenes will be connected with this academy. Its library becomes the greatest in the ancient world (see the Library at Alexandria). And immigrants from elsewhere in the eastern Mediterranean soon turn this relatively new place into a great cosmopolitan centre.

The Jews of Alexandria demonstrate the ability of a Jewish community to flourish in a new context without losing its identity. They integrate so fully with the secular life of the city that their own first language becomes Greek. It is they who first use the word diaspora (Greek for 'dispersion') to describe Jewish communities living outside Israel.

Soon many of them no longer understand Hebrew. But they refuse to let this diminish their strong sense of a shared identity as God's special people, according to the covenant revealed in a book which they now cannot read. They commission, with Ptolemy's support and approval, the first translation of the Bible, the famous Greek version known as the Septuagint. And their Synagogue is the earliest of which there is evidence.

In addition to the library, Ptolemy plans the great lighthouse on the island of Pharos at the entrance to the harbour. It is built in about 280, under his successor Ptolemy II.

It is by far the most impressive lighthouse of antiquity, becoming famous as one of the Seven wonders of the world.

The lighthouse consists of a three-tier stone tower, said to be more than 120 metres high, which has within it a broad spiral ramp leading up to the platform where fires burn at night. They are reflected out to sea by metal mirrors. Above the fires is a huge statue, of either Alexander or Ptolemy in the guise of the sun god, Helios.

The lighthouse survives until the 12th century. In the 15th century a fort, still standing today, is built from its ruins.

Greek science in Alexandria: from the 3rd century BC

Classical Greece has produced a brilliant tradition of theorists, the dreamers of science. Attracted by the intellectual appeal of good theories, they are disinclined to engage in the manual labour of the laboratory where those theories might be tested.

This limitation is removed when the centre of the Greek world transfers, in the 3rd century BC, to Alexandria. In this bustling commercial centre, linked with long Egyptian traditions of skilled work in precious metals, people are interested in making practical use of Greek scientific theory. If Aristotle says that the difference in material substances is a matter of balance, then that balance might be changed. Copper might become gold.

Among the practical scientists of Alexandria are men who can be seen as the first alchemists and the first experimental chemists. Their trade, as workers in precious metals, involves melting gold and silver, mixing alloys, changing the colour of metals by mysterious process.

These are the activities of chemistry. The everyday items of a chemical laboratory - stills, furnaces, flasks - are all in use in Alexandria.

There are strong mystical influences in Egypt, some of them deriving from Babylonian Astrology, and this tradition too encourages experiment. Astrologers believe in many hierarchies, among the planets in the heavens but also among metals in the earth. Lead is the lowest of the metals, gold the highest. Left to itself, out of sight in the earth, lead may slowly be transformed up the scale to achieve ultimate perfection as gold.

If this process could be accelerated, in the back of a jeweller's shop, there would be certain immediate advantages. In the early centuries, the experiments of chemistry and alchemy go hand in hand.

Euclid and Archimedes: 3rd century BC

Euclid teaches in Alexandria during the reign of Ptolemy. No details of his life are known, but his brilliance as a teacher is demonstrated in the Elements, his thirteen books of geometrical theorems. Many of the theorems derive from Euclid's predecessors (in particular Eudoxus), but Euclid presents them with a clarity which ensures the success of his work. It becomes Europe's standard textbook in geometry, retaining that position until the 19th century.

Archimedes is a student at Alexandria, possibly within the lifetime of Euclid. He returns to his native Syracuse, in Sicily, where he far exceeds the teacher in the originality of his geometrical researches.

The fame of Archimedes in history and legend derives largely from his practical inventions and discoveries, but he himself regards these as trivial compared to his work in pure geometry. He is most proud of his calculations of surface area and of volume in spheres and cylinders. He leaves the wish that his tomb be marked by a device of a sphere within a cylinder.

A selection of titles from his surviving treatises suggests well his range of interests: On the Sphere and the Cylinder; On Conoids and Spheroids; On Spirals; The Quadrature of the Parabola; or, closer to one of his practical discoveries, On Floating Bodies.

Human vivisection: c.300 BC

Early in the 3rd century BC two surgeons in Alexandria, Herophilus and Erasistratus, make the first scientific studies designed to discover the workings of human anatomy.

The cost of their contribution to science would be considered too high in modern times (they acquire much of their information from human vivisection, the patients being convicted criminals). But Celsus, a Roman writer on medical history, energetically justifies the suffering of the criminals as providing 'remedies for innocent people of all future ages'.

Mechanical organ: 3rd century BC

Pipes of varying sorts are among the earliest of musical instruments, and pipers must often have imagined a pipe too large for human lungs. A scientist in Alexandria, by the name of Ctesibius, is credited with being the first to invent an organ - with a hand-operated pump sending air through a set of large Pipes. Each pipe is played by pressing a note on a board. This is the beginning of Keyboard instruments.

By the time of the Roman empire, a few centuries later, the organ is a familiar and popular instrument - playing a prominent part in public games and circuses as well as private banquets. The emperor Nero, an enthusiastic performer, is proud of his talents on the organ.

The circumference of the earth: calculated in about 220 BC

Eratosthenes, the librarian of the Museum at alexandria, has more on his mind than just looking after the scrolls. He is making a map of the stars (he will eventually catalogue nearly 700), and he is busy with his search for prime numbers; he does this by an infinitely laborious process now known as the Sieve of Eratosthenes.

But his most significant project is working out the circumference of the earth.

Eratosthenes hears that in noon at midsummer the sun shines straight down a well at Aswan, in the south of Egypt. He finds that on the same day of the year in Alexandria it casts a shadow 7.2 degrees from the vertical. If he can calculate the distance between Aswan and Alexandria, he will know the circumference of the earth (360 degrees instead of 7.2 degrees, or 50 times greater).

He discovers that camels take 50 days to make the journey from Aswan, and he measures an average day's walk by this fairly predictable beast of burden. It gives him a figure of about 46,000 km for the circumference of the earth. This is, amazingly, only 15% out (40,000 km is closer to the truth).

The Roman empire

The Donations of Alexandria: 34 BC

A great crowd gathers in a stadium in Alexandria. All eyes are on two tiers of thrones. On the upper level sit Antony and his wife Cleopatra, robed as the Egyptian goddess Isis. On four lower thrones are their own three children together with Cleopatra's eldest son, Caesarion, the child of Julius Caesar.

In the ensuing ceremony, later known as the Donations of Alexandria, Antony distributes the kingdoms of the eastern Mediterranean to his new family.

Antony declares Cleopatra to be the Queen of Kings and Caesarion the King of Kings, jointly ruling over Egypt and Cyprus and joint overlords of the kingdoms of the other children. To Alexander, his own elder son, aged six, he gives the territories east of the Euphrates; to Alexander's twin sister, Cleopatra, he gives Libya and Tunisia; and to his younger son, Ptolemy Philadelphus, aged two and appearing in Macedonian costume, he gives Syria and much of Anatolia.

It is a gorgeous occasion, but one which will need to be explained on the battlefield.

Greek atmospheric devices: 1st century AD

Hero, a mathematician in Alexandria in about AD 75, enjoys inventing mechanical gadgets, which he describes in his work Pneumatica. Whether he has the technology to make them we do not know, but his scientific principles are correct.

One such gadget is a primitive version of a steam turbine. Hero says steam should be directed into a hollow globe with outlets through nozzles on opposite sides of the circumference. The nozzles are directed round the rim of the globe. As the steam rushes out, like sparks from a catherine wheel, the globe spins.

Hero makes another significant use of atmospheric pressure in a magic altar, putting to work the expansion and contraction of air. A fire heats the air in a container, causing it to expand and force water up a tube into a bucket. The increased weight of the bucket opens the doors of an altar. When the fire is extinguished, the air contracts, the water in the bucket is sucked out and the doors close.

Any temple managing to work this trick is certain to attract more pilgrims, and more money, than its rivals.

Hero's dioptra: 1st century AD

One of the surviving books of Hero of Alexandria, entitled On the Dioptra, describes a sophisticated technique which he has developed for the surveying of land. Plotting the relative position of features in a landscape, essential for any accurate map, is a more complex task than simply measuring distances.

It is necessary to discover accurate angles in both the horizontal and vertical planes. To make this possible a surveying instrument must somehow maintain both planes consistently in different places, so as to take readings of the deviation in each plane between one location and another.

This is what Hero achieves with the instrument mentioned in his title, the dioptra - meaning, approximately, the 'spyhole' through which the surveyor looks when pinpointing the target in order to read the angles.

Hero adapts, for this new and dificult task, an instrument long used by Greek astronomers (such as Hipparchus) for measuring the angle of stars in the sky. It is evident from his description that the dioptra differs from the modern theodolite in only two important respects. It lacks the added convenience of two inventions not available to Hero - the Compass and the Telescope.

A Roman port: 1st - 4th century AD

During the Roman empire Alexandria retains its commercial importance, for it is the port through which the grain of Egypt passes on its way to the granaries of Italy. With the decline of Greek influence, the city loses something of its intellectual edge - though the encyclopedic efforts of Ptolemy in the 2nd century AD will exert a long and profound influence, and an important step in Algebra is taken in Alexandria at much the same time.

A disaster in AD 215 demonstrates that the inhabitants have also retained an independent spirit. The emperor Caracalla, visiting Alexandria, becomes the butt of some disrespectful satires. His response is to order a widespread massacre of the citizens.

The city of Arius: AD 323

In the 4th century Alexandria plays a prominent role in an entirely new context, that of Christian dogma. The preeminence of the city in the eastern Mediterranean makes it an important early centre of Christianity long before Constantine bestows official approval on the religion. What the Christians of Alexandria believe is a matter of significance.

In 323 a priest, Arius, is dismissed from his post in one of the city's churches for holding heretical views on the Trinity. In Alexandria itself orthodoxy soon prevails again. But the Alexandrian heresy echoes round Europe and north Africa for the next two centuries.

Eclipsed by an old rival: 7th century AD

Alexandria suffers a double blow in the 7th century. First it falls victim to the final struggle between the Persian and Byzantine empires, being captured by the Persians in 616. Then, after a siege lasting more than a year, it is taken without bloodshed in 642 by the Arabs in their first great wave of expansion.

The Arab commander establishes a garrison town on the Nile. This gradually develops into the city of Cairo, which from the 10th century overshadows Alexandria. The new city is on the opposite bank from the old site of Memphis, the capital of the first Egyptian dynasties. The centre of political power in Egypt returns, after the Alexandrian centuries, to its original home.
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