of a 1,000-foot (306-meter) cliff on Mount Mycale. The north-south streets were steep, even needing to be stepped in places; the east-west streets, approximately following the contours, were easier to negotiate. Provision was made for city growth within the encircling walls. In the event, the population remained at 3,000 and more than half the enclosed area was never developed. Reserves for public spaces were part of Hippodamos’s plan, and the agora stood upon a central terrace.

Around 450 b.c., Hippodamos was commissioned by Perikles to redesign parts of Piraeus, the port of Athens. It stood less than 6 miles (9.6 kilometers) southwest of the city on a peninsula surrounded by the Saronic Gulf. He rebuilt the original fortified Themistoclean port, by then about thirty years old, with a well-defined grid of broad streets defining long rectangular blocks. His plan gave better access to the three harbors, dedicated respectively to grain vessels, general cargo ships, and the navy. The parallel Long Walls, about 600 feet (183 meters) apart, were completed in 431 b.c. to protect the supply line between Athens and its port during the Peloponnesian War with Sparta.

There are several other attributions. Hippodamos almost certainly had a hand in the foundation of the colony of Thurii in southern Italy around 444 b.c. Very regular orthogonal extensions to the city of Olynthos, in what is now Macedonia, were laid out soon after 432 b.c. But it may be that Olynthos and the much later city of Rhodes (408 b.c.) on the Aegean island of the same name were laid out by others who implemented the Hippodamean form. That easily surveyed orthogonal form continued to be influential and was perhaps modified by the Romans in any number of their colonial towns. It was revived in the fifteenth century as one of the theoretical bases of Renaissance urban design. Much later, the planners of cities in the New World employed the grid: Savannah, Philadelphia, Chicago, and New York City are all evidence of that. So is San Francisco, where its imposition on a hilly site, even if it provides locations for exciting movie car chases, underlines its suitability for little but the flattest terrain.

See also

Timgad, Algeria

Further reading

Castaglioni, Ferdinando. 1971. Orthogonal Town Planning in Antiquity. Cambridge. MA: MIT Press.

Mahoney, Daniel J. 1998. The Conservative Critique of Social Engineering. The American Enterprise (September): 43–44.

Murray, Oswyn, and Simon Price, eds. 1990. The Greek City: From Homer to Alexander. Oxford, UK: Oxford University Press.

Hydraulic boat lifts

When inscribing the Canal du Centre boat lifts in Belgium on its World Heritage List in 1998, UNESCO commented that they “represented the apogee of the application of engineering technology to the construction of canals.” That holds true for each example described here. The boat lifts exemplify the seemingly limitless mechanical ingenuity of the Victorian Age. The Industrial Revolution, first in Britain and then in the rest of Europe and North America, saw the necessarily rapid growth of inland transportation networks. Although they were soon augmented (and often replaced) by railroads, canals were the main arteries of industry and commerce. Differences in water levels along their length and at their junctions with rivers were normally overcome by building locks. In order to save time, creative engineers developed a hydraulic mechanism known as a boat lift, which could replace several conventional locks. Among the most ingenious devices of the machine age, the boat lift continued to be refined into the early twentieth century. The principle was simple: a boat or barge entered a watertight trough that was raised or lowered by filling or emptying a counterbalancing trough.

It is likely that the first commercial boat lift was built in 1838 on the Grand Western Canal in the English county of Devon. The canal, first suggested in 1768, was intended to link the Bristol Channel on the west coast and the English Channel on the east. Construction did not begin until 1810 and four years later an 11-mile (17.6-kilometer) stretch was completed. Extensions were built, and by 1838 the canal reached as far as Taunton in Somerset. A decade later the Great Western Railway linked Bristol and Exeter, and work on the canal was discontinued. But the boat lift served vessels carrying limestone from Tiverton