The Magazine

Classical Metropolis

The Alexandria of antiquity.

May 7, 2007, Vol. 12, No. 32 • By CHARLOTTE ALLEN
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The first scientist of note to arrive in Alexandria was Aristarchus of Samos (circa 310-circa 230 B.C.), who had studied at the school of Pythagoras and also with Ptolemy II's tutor, Strato of Lampsacus, who had in turn studied at Aristotle's school, the Lyceum, in Athens. Strato, whose epithet was "the Physicist," held that the universe was a mechanism that could be explained without recourse to divine forces, a peculiarly modern notion that became a hallmark of Alexandrian science. At least as Pollard and Reid would have it, Aristarchus proved an apt pupil of his master: In an effort to calculate (erroneously but not too erroneously) the relative sizes of the earth, sun, and moon, Aristarchus realized that the sun was vastly larger than the earth and concluded that the conventional model proposed by Plato and Aristotle, in which the sun revolved around a spherical earth, made no sense given the relative size of the two bodies. Aristarchus therefore hypothesized a heliocentric universe, anticipating Copernicus by some 1,800 years. His contemporaries considered him either impious or daft.

The latter opinion came from Archimedes (circa 287-212 B.C.), the mathematician and engineer who (so Pollard and Reid argue on the basis of his friendships with prominent Alexandrian scientists) sojourned in Alexandria between stints in his native Syracuse inventing advanced catapults and ships' pulleys and crying, "Eureka!" on discovering that he displaced his volume in water in the bathtub. Aristarchus' heliocentric theories were eventually all but forgotten, supplanted during the second century A.D. by the precepts of another Alexandrian, the astronomer Claudius Ptolemy (no relation to the Egyptian rulers by that name), whose Almagest laid out the elaborate geocentric system of sun, moon, and other heavenly bodies that held sway in the West until the dawn of the modern era.

Other famous Alexandrian mathematicians, scientists, and inventors included Euclid (circa 325-circa 265 B.C.), the father of geometry; the geographer Eratosthenes of Cyrene (circa 275-195 B.C.), who calculated with amazing accuracy the circumference of the earth; the barber (by day) Ctesibus (circa 200 B.C.), inventor of the water clock that allowed the ancients to tell time indoors for the first time; and Hero (circa 100 A.D.), an engineer-geometrician who devised elaborate hydraulics-driven machines that anticipated the Industrial Revolution. Hero, unfortunately, failed to discover the other component of the Industrial Revolution, cheap coal-fired power, so it remained more economical to buy slaves to do the work that could be performed by Hero's steam-and-water contraptions, which were relegated to providing flashy special effects at theaters and temples.

The second-century physician Galen, whose most famous patient was the emperor Marcus Aurelius, researched the circulatory system while in Alexandria, and in the third century A.D., the mathematician Diophantus invented a rudimentary form of algebra. Modern chemistry, via medieval alchemy, may have its origins in the hermetic writings of Alexandrian late antiquity.

Pollard and Reid are makers of historical documentaries for television (PBS, BBC, National Geographic), not academic historians, and they freely mix the yarns that the ancient biographers of scientists spun about their subjects with more verifiable facts. Nonetheless--or perhaps because of their amateur status--they tell the story of ancient Alexandrian science with relish and brio that few university scholars can muster these days. Their lively and lucid description of Eratosthenes' methodology for calculating the earth's circumference at 25,000 miles--which involved simultaneously measuring the angle of the sun on the day of the summer solstice at Alexandria and the city of Syene some 600 miles up the Nile--is the book's high point, not only because Eratosthenes' calculations were so accurate but because he also figured out, with equal near-accuracy, that the earth's axis is tilted toward the sun on solstice day.

"His proof provided the first scientific explanation of a phenomenon that every Greek and Egyptian experienced: the seasons," write Pollard and Reid.

The two write with equal brio, again mixing gossipy anecdotes from Plutarch and elsewhere with verifiable history, about the Ptolemy family that ruled Alexandria and the entire land of Egypt until the suicide of the last Ptolemy, Cleopatra, turned Egypt into a Roman province in 30 B.C.