with the air supply now controlled by bellows and blowpipes.
A much earlier metallurgical invention, however, was the
lost-wax process for casting bronze, which dates to the My-
cenaean Period (1600–1100 b.c.e.) and is still used by artists
today. Th e making of a wax mold of an artwork into which
molten bronze is poured allows for great detail, making the
Greeks renowned throughout the ancient world for the qual-
ity of their bronze sculptures. Since bronze is easily melted
down and reused, few artworks have survived. Another in-
novation of great artistic import was the development in Ath-
ens of a black high-gloss permanent glaze for pottery, which
made Athenian vases highly sought-aft er exports throughout
the Mediterranean.
Th e Hippocratic Corpus, a series of writings attributed
to the physician Hippocrates (ca. 460–ca. 377 b.c.e.), contains
numerous references to medical instruments: In this sense it
is the earliest extant scientifi c work to discuss technology. Of
particular interest is the Hippocratic bench, a device with
posts, straps, and cords designed for traction and the reduc-
tion of dislocations.
As in the modern world, compelling state interests led
to a great deal of innovation in military matters, and we
are also well supplied with sources on military technology.
In addition to archaeological fi nds, there exist treatises on
military technology and descriptions of such innovations in
the historical accounts of battles. Th e Greeks were the fi rst
to develop artillery (without gunpowder) by making use of a
variety of mechanical means to launch projectiles. Th e gast-
raphetes, invented in 399 b.c.e., was a device for launching
arrows or stones and resembled a medieval crossbow. Torsion
catapults were developed later in the fourth century b.c.e.
and underwent a steady series of technical improvements
throughout antiquity. Th e Greek mathematician and inven-
tor Archimedes (ca. 287–212 b.c.e.) is credited with the de-
velopment of various siege engines and defensive weapons,
including a pivoting crane to drop stones on enemy ships and
scaling ladders, a crane with a claw for grabbing the bow of
an enemy ship and overturning it, and a series of parabolic
mirrors that could be focused on an enemy ship to set it on
fi re. (A recent experiment by students at the Massachusetts
Institute of Technology has suggested that this was, in fact,
feasible.)
A clever but entirely low-tech military invention devel-
oped in Sparta by the fi ft h century b.c.e. was the scytale (also
spelled skytale), a device for transmitting messages in code.
Th e scytale consisted of a rod around which a leather strap
was wrapped in a long spiral. A message would be written
across the strap, which would then be unrolled and sent to the
recipient, who would possess a rod of equal size. When rolled
around the recipient’s rod, the strap would reveal the origi-
nal message; anyone intercepting it without the decoding rod
would fi nd a string of apparently random letters.
Th e intellectual atmosphere at Alexandria was particu-
larly conducive to innovation, owing perhaps to the combina-
tion of royal patronage for the sciences and access to Egyptian
learning. Th e most important of the surviving treatises are
those of Hero (fl. fi rst century c.e.), who wrote on a vast va-
riety of subjects, giving details on the building of surveying
devices, hydraulics, and pneumatics. Of these innovations,
many are of practical value: the pump and the accurate wa-
ter clock developed by his predecessor Ctesibius (fl. second
century b.c.e.), for example, and the water organ (the world’s
fi rst keyboard instrument). Others are clearly designed to be
impressive rather than practical. Hero wrote an entire book
devoted to automata (self-operating mechanisms), which
include slot machines for dispensing water for ritual cleans-
ing before entering a temple, pneumatically powered temple
doors that would open automatically when a fi re was lit on
the altar, steam-powered tops, and a variety of devices for
making small mechanical birds and other animals move. It
is unknown how many of these devices were actually built or
how widespread their use was, but the discovery of a complex,
multigeared mechanism for computing the positions of the
stars and planets (the Antikýthēra device, named aft er the
island near which it was found) shows that the Greeks were
capable of precise engineering, building what was in eff ect a
mechanical computer.ROME
BY DAVID KELLY
Many of the inventions that are credited to ancient Rome are
related to construction, travel, and water management. One
of the principal reasons that Romans were able to build large-
scale projects was their improvement in concrete. Starting in
237 b.c.e. the Romans developed a method of mixing tradi-
tional claylike building materials with such diverse elements
as volcanic ash from Pozzuoli, a village near Naples, which
was found to be a strong binding agent; horsehair, which gave
the concrete fl exibility; and blood, which helped inhibit frost.
Roman improvements in concrete enabled them to make a
product that could be molded to diff erent shapes and yet was
resistant to moisture. With this basic invention they could
be more imaginative with architectural design, incorporat-
ing arches and domes to raise buildings up toward the sky,
freed of having to rely on stone blocks as their main building
material.
Th e improved concrete also enabled Romans to build
hundreds of miles of water-transportation tunnels, or aque-
ducts, which are considered one of the greatest achievements
of the Roman Empire. Roman aqueducts transferred water
from sparsely inhabited regions to all of the urban capitals
of the empire. In the city of Rome itself, for instance, roughly
300 million gallons of water were brought in from the sur-
rounding countryside each day, all without the use of pumps
or any machinery whatsoever, relying solely on the power of
gravity. Besides the fl exibility that concrete gave them, the
Romans also developed a precision in their understanding of
hydraulic engineering that made aqueduct technology pos-
sible: Th ey calculated the downward angle needed to moveinventions: Rome 601