jewelers, cabinetmakers, and armorers. The Museum in Alexandria may have been decorated with
opulent sculptures and mosaics, but the craftspeople who created those decorations did not enjoy the same
status as the poets, thinkers, and scientists that the Museum housed.
The Museum was in many respects similar to the Academy that Plato had founded about one hundred
years earlier but, while the Academy was privately funded, the Museum was supported by the vast
financial resources of the kingdom of the Ptolemies. And, while the Academy was dedicated to a minor
local hero, the Museum was, as its name indicates, a shrine to the Muses, who were worshipped
throughout the Greek world as the divine patrons of all aspects of culture. All aspects of culture were
indeed represented in the studies undertaken by the scholars resident in the Museum. Their inspiration
came, however, not only from the Muses but from their predecessors, some of whom were affiliated with
Plato’s Academy, men like Aristotle, whose writings include influential works concerned with the study
of literature, political science, biology, astronomy, logic, ethics, and many other topics. The interests of
the scholars whose research was conducted in the Museum were similarly comprehensive. Occasionally
that range of interests could be found represented in a single individual. One of the most remarkable
figures associated with the Museum was Eratosthenes of Cyrene (map 16), who lived in the third century
and who succeeded Apollonius of Rhodes as head of the library at the Museum. His contemporaries gave
Eratosthenes the nickname “Pentathlete,” implying that he was proficient in many fields (but also perhaps
with the implication that he was not the absolute best in any one of them).
One of the achievements for which Eratosthenes is best known is his successful measurement of the
circumference of the earth. As we saw above, the plaything that Apollonius puts into the hands of Eros
shows that the Greeks of the Hellenistic Period were aware that the earth is spherical in shape.
Eratosthenes learned that, at high noon on the day of the summer solstice, an upright object in the Egyptian
city of Syene (modern Aswan) casts no shadow. He reasoned that, by measuring the angle of the sun’s
shadow cast at that moment in the city of Alexandria (which he thought to be due north of Syene), he could
determine what fraction of the earth’s circumference was occupied by the distance between the two cities
(figure 73). That angle turned out to be equal to one-fiftieth of a circle, or as we would say 7.2 degrees of
arc; therefore the circumference of the earth is fifty times the distance between Alexandria and Syene.
That distance, as the ibis flies, is 845 km, making the earth’s circumference 42,250 km, reasonably close
to the circumference as measured by modern methods, or 40,075 km. As it happens, Alexandria and Syene
do not lie on the same meridian, and Syene is not directly on the Tropic of Cancer, nor is the earth quite
spherical. Be that as it may, the method used by Eratosthenes cannot be faulted. That method involves the
application of geometry to the messy world with which we come in contact every day. It will be
remembered that geometry was central to the activity carried out at Plato’s Academy and, while
Eratosthenes was proficient in geometry and mathematics, he was by no means the most accomplished
Hellenistic scholar in those fields.