The Ancient Engineers, page 7
Moreover, such a house was less vulnerable to burglary than one with windows opening to the outside.
Finally, a blank wall shielded the householder from the eager eyes of tax gatherers and other royal agents. Some men living under a despotism managed to get rich, even though they were not members of the governmental apparatus. Such men—merchants for example—were careful to hide their wealth from the despot's agents, lest they be beggared by sudden tax claims or slain on some trumped-up charge to give the autocrat an excuse for taking all. An Iranian proverb expressed it: "If you are being fattened by someone, you may expect very quickly to be slaughtered by him."8
Because of the scarcity of fuel in Mesopotamia, kiln-dried bricks were rarely used in private houses. As a result, the householder was kept busy during the winter trying to patch up his house as fast as the rains dissolved it away. When, once in a generation, the task became hopeless, he brought out his movables, knocked down the walls, leveled and smoothed off the debris to make a new floor, and built another house on the ruins of the old.
As the early cities of the ancient watershed kingdoms had neither sewers, garbage disposal, nor trash collection, rubbish accumulated and constantly raised the level of the streets. Older houses could be distinguished by the fact that their entrances were below street level.
This was particularly true of temples. Most large temples stood in a sacred precinct, the temenos, surrounded by a wall. Because the temple was more substantially built than private houses, it lasted longer. Also, as the temenos was holy, it was kept free of rubbish, so that the level of its grounds did not rise with that of the street outside. In time a temple and its inclosure might be almost buried from sight as the street levels rose around them.
Thus cities originally built on the plain slowly rose on hills of their own debris. Today Iraq is dotted with these hills or tells,9 scores of which still await the picks, shovels, and whisk brooms of archeologists.
When men first began to build large numbers of houses close together, two methods of arranging them grew up. If a city grew out of a village, the dwellers were likely to continue to let everybody put his house where he pleased.
The result was a city laid out like the oldest parts of Paris or Boston today. Narrow, winding alleys, hardly wide enough for two men to pass and unusable by large beasts of burden or vehicles, ran every which way. This was no great fault in a village, where too few people were abroad at any one time to constitute a traffic problem.
But, as the population grew, traffic congestion grew faster. Hence the ancient metropoleis were forced, like modern cities, to regulate traffic. The winding-alley village layout also aggravated the problems of waste disposal, fire protection, and law enforcement as the city waxed larger.
So when, as sometimes happened, a group of people came to a likely place and said: "Let us build a city here," their leaders often had the wit to plan the city from the start. They laid it out with straight streets, some of them wide avenues, in a regular pattern. They kept at least one area clear of buildings for a marketplace, and reserved another space for temples and palaces.
The usual pattern was a gridiron or checkerboard with streets crossing at right angles. The cities of the Indus Valley showed this plan, as did some Mesopotamian and Egyptian cities. Peoples much given to sending out colonies, such as the Phoenicians, the Greeks, and the Romans, had many occasions for laying out cities in this manner.
A ceremony marked the founding of a city. The head man traced out the line of the wall, often by plowing a furrow with gaps for the gates. This line then became invested with magical properties.
The simple gridiron plan is not always the best possible, according to modern city planners, who like to include a few diagonal streets to carry heavy traffic and a winding layout for residential sections. But the gridiron was the best that ancient city planners could envisage.
In locating a city, ancient town planners were often torn between two choices: to put the city at the bottom of a valley for nearness to water, or to place it on a hilltop to make it easy to defend. The choice depended upon the likelihood of attack.
The survival of the hilltop city or fortress depended on getting water when besieged. Some cities solved the problem thus: When a spring flowed from the hill below the walls, the builders drove an inclined tunnel from inside the walls down through the rock to the spring, which they then walled in so that it could be approached only by this tunnel. Sometimes another tunnel carried the water inwards, under the fortified place, where it filled an underground cistern.
The kings of Mycenae in Greece, reigning at the time of the legendary Trojan War (—XII), took this precaution. So did the Jebusites, who lived in Jerusalem before the Israelites captured it. The Jebusites ran a tunnel from the spring of Gihon, southeast of the city, to a natural cave beneath the city. Then they excavated a 40-foot vertical shaft from this cave up to the surface, so that women could lower their vessels from the surface down to the reservoir thus created.
When David attacked Jerusalem (about —1000) the warrior Joab led a party of Israelites up the shaft, captured the city, and thus made himself David's commander in chief. About 300 years later, King Hezekiah of Judah blocked off the Jebusite tunnels and made a tunnel of his own, leading to the Pool of Siloam at the southern end of the Valley of Cheesemongers. An inscribed tablet marked the place where the two tunneling gangs, starting from points a third of a mile apart and boring from opposite directions, met.
The two great Mesopotamian rivers meander southeastward across the Euphratean plain, approaching to within twenty miles of each other near Baghdad. Then they diverge for another 300 miles. At last they join and flow together for fifty miles into the Persian Gulf. According to one theory (with which not all students agree) this gulf in ancient times extended farther to the northwest than it now does, and the rivers entered it separately. Silt from these rivers has since filled up the head of the gulf.
Both rivers, like the Mississippi and other large flood-plain streams, have changed their courses many times, often leaving prosperous cities stranded, to decay and die in the midst of a desert. In the upper part of its course, where the slope is steep and the current swift, a river picks up silt from the bottom. Then farther down, as the river nears the sea, its slope becomes gentler and its current slower, so that it drops the silt it carried. Therefore the bottom in this part builds up higher and higher.
In time, during the high-water season, the river overflows its banks.
Sometimes it makes a whole new channel in some other part of the flood plain. Because men try to keep the river in one place by building up the banks with levees, the river rises higher and higher above the surrounding country, and a flood is more destructive when it does come.
Flood problems were more acute in Mesopotamia than in Egypt. For one thing, the Tigris and Euphrates carry about five times as much silt for a given volume as the Nile. Hence the bottoms of these rivers rise faster, and they change their courses more often.
For another, they are less regular than the Nile in the date and degree of the rise of their waters. Their high level occurs in the spring at an awkward time, too late to help with winter crops and too early for summer crops. Therefore, much storage of water is needed to raise good crops on this fertile ftatland.
Although the Euphrates is much the longer of the two rivers, the Tigris carries over twice as much water as its sister. It is also swifter and more unpredictable. Moreover, being faster, it digs a deeper trench and so is less easily used for irrigation.
Because the leading civilizations of antiquity arose in broad river valleys, and because floods are the deadliest natural catastrophes in such valleys, these civilizations all developed flood legends as part of their mythology. The Sumerians had a legend about the pious Ziusudra, who by building an ark saved himself and his family from a great flood sent by the gods. The legend evolved down the centuries and passed from folk to folk, so that Ziusudra became the Utnapishtim of the Assyrians, the Noah of the Hebrews, and the Deukalion of the Greeks.
Across the yawning gulf of 5,000 years, we see the sun-browned Sumerians beginning the endless task of breaking the rivers and the plain to the use of man. As century followed century, Mesopotamia came to be damascened by an azure web of canals, which tamed the mighty Euphrates, clothed the desert in rippling fields of golden grain, and moistened the roots of date palms planted along their banks in endless rows.
In the third millennium B.c., for example, King Entemanna of Lagash built an especially large canal, which ran from the Tigris south along the 46th meridian to the Euphrates. This canal can still be traced by a line of lakes, streams, and marshes. Later an even larger canal, the Nahrwan, over 200 miles long and 400 feet wide, paralleled the Tigris along its left bank from Baghdad (then a mere village) to a place near modern Kut al-'Amara.
Keeping up such a canal system in Mesopotamia presented special difficulties. Because of the lack of timber and stone, there was no easy way to reinforce the canal banks. When these banks were simply made of piled-up mud, they easily fell into disrepair.
An irrigation canal must be carefully planned and maintained. It must be a little above the surface to be irrigated, and it must have a slight but constant slope to keep the water flowing. If the slope is too steep, the water flows too fast and eats away the banks. If it is too gentle, weeds and silt block the channels. The domestic goat, that ancient scourge of the Near East, breaks down the banks by scrambling up and down them. Constant repairs are therefore needed. As soon as a section begins to silt up, it must be dredged out lest it ruin the circulation of the area.
Lacking stone and wood, the Mesopotamians used cane reeds, tied in bundles or woven into mats, as reinforcing material. They used these reeds not only in their canal work but also in house building. Therefore Mesopotamian towns maintained a curious institution: the municipal marsh, a patch of swamp deliberately kept as a wetland where the useful reeds could grow.
Mesopotamian irrigation was of the basin type, like that in the Egyptian Delta. As such basins do not have mechanical gates or sluices, they are opened by digging a gap in the surrounding embankment and closed by shoveling mud into this gap again. Hence Mesopotamian irrigation farming was a very laborious business.
For hoisting water, the Mesopotamians used a swape like that of Egypt. Sometimes they employed a battery of these swapes, the first one hoisting water to a certain height, the next hoisting it still farther, and so on. They also devised the first advances on the simple bucket hoist. One was the pulley, which appeared before —1500 and which made much easier the task of drawing water from a well.
A main form of engineering advance is the substitution of continuous for intermittent motion, and rotary for back-and-forth motion. The Mesopotamians attained this stage by about —1200. A legal document on clay orders a man to replace a water-raising treadwheel, 20 feet long with seventeen steps, which he had borrowed and lost.
Mesopotamian laws not only required farmers to keep their basins and feeder canals in repair but also called upon everybody in the kingdom to turn out with hoe and shovel in times of flood, or when a new canal had to be dug or an old one repaired. Times of trouble caused the canal system to decay, so that extra effort was required to put it back into good condition.
With the best of care, however, canals would last only about a thousand years. Then they were abandoned and others were built. Today, four or five thousand years later, Iraq is still ridged with the embankments of these abandoned canals, crisscrossing the country in parallel lines.
For four thousand years the Mesopotamian canal system supported a denser population than lives there today. Then in 1258 the Mongols of Hulagu Khan conquered Mesopotamia, sacked Baghdad, and killed the last of the Khalifahs of Baghdad. Looking upon all sedentary peoples as vermin to be wiped out, the Mongols destroyed the irrigation system and allowed a famine to reduce the population to a fraction of its former size.
Iraq remained under Mongol rule for about a century. As nothing was done to rebuild the canals, the land went back to desert and swamp. Subsequently plundered by Arabs, Turks, and Kurds, the region was almost depopulated, as happened to many other lands in ancient times as the result of barbarian raids and conquests. Iraq never even began to recover until it became independent in +XX.
However, the ruin of Mesopotamian irrigation may not have been due solely to the Mongols. There is reason to think that agriculture in this region had been decaying for centuries before the Mongol invasion. The reason for this decay has to do with salt.
In the lower strata of the alluvial soil of Mesopotamia lie thick beds of salt. This salt may be a relic of a prehistoric time when the sea covered the whole Euphratean plain. When such a soil is irrigated again and again for thousands of years, capillary action draws salt water to the surface. As the water evaporates, the salt remains and little by little makes the land useless for farming. So perhaps, even with modern agricultural methods, Iraq will never again be the teeming farmland it was in ancient times.
Once the Mesopotamians had learned to irrigate their land and wall their cities, they could turn their attention to building temples and palaces—the only gay and handsome structures in this almost treeless flat-land of brown mud-brick villages.
The modern ceremony of breaking ground for a public work, with some puffing politician turning the first spadeful of earth, goes back to ancient Mesopotamia. A relief from the third millennium b.c. shows the Sumerian king, Ur-Nanshe of Lagash, in the unkingly pose of bearing a basket on his head. Presumably the basket contains the first bricks for a temple or other public work, because a similar relief shows the dreaded Ashurbanipal of Assyria (—VII) carrying a similar basket for the rebuilding of the great temple of Marduk in Babylon.
The first temples of Mesopotamia were built in the fourth millennium b.c. with starkly rectangular lines. They had blank brick outer walls, pierced high up by a few small triangular windows. The austere aspect of these temples gives the impression that they were designed, by some trick of time travel, by twentieth-century architects of the functionalist school. Strict symmetry and right-angled corners, however, the Mesopotamians did not especially admire.
Later Mesopotamian temples were brightly decorated. This was done by pressing cones of colored brick, about the size of a finger, into the wet plaster that covered the walls and pillars, so that only the bases of the cones could be seen. The walls and pillars of the temples of Uruk10 and Uqair were gay with mosaics formed by these cones, placed in gaudy patterns of colored polka-dots. Even richer effects were obtained by affixing wafers of copper plating or colored stone to the bases of the cones.
To make them more impressive, temples were sometimes raised upon pyramidal platforms of brick. These pyramids became larger and larger until two distinct types of sacred structure evolved. The first was the temple proper: a massive, pillared hall on the ground. The other was the ziggurat,11 a lofty pyramid of brick, with setbacks, staircases, and a shrine on top. The only ziggurat that still survives in anything like its original form stands at Ur in the South, amid what is now a desolate wilderness.
There are several theories about the purpose of ziggurats. The theory that most persuades me is that these towers were used like the Palestinian "high places" mentioned in the Bible, or the large wooden pillars on the grounds of Syrian temples. In Syria, a priest would climb to the top of such a pillar. Another priest at the foot of the pillar collected offerings from the faithful as they asked him questions.
This priest shouted each question up to the priest on the pillar, who in turn shouted it up to the gods. The pillar brought the petitioning priest nearer to heaven so that the gods could hear him more plainly. So, I suspect that ziggurats likewise furnished Mesopotamian priests with an elevated platform whence to address the powers above with the needed audibility.
The most famous ziggurat was raised at Babylon in honor of Marduk, the Babylonian Jupiter. The Bible calls this ziggurat the Tower of Babel. To the Babylonians it was Etemenanki, the Cornerstone of the Universe, originally built by the gods themselves. After several destructions and rebuildings, it reached its final form under Nebuchadrezzar II, around —600. Then it towered skyward for nearly 300 feet and was covered with enameled bricks in colorful patterns, as if it were clothed in the scaly skin of some monstrous reptile. Could the legend of the Confusion of Tongues be an echo of labor troubles during the building of Ete-menanki? It is a tempting speculation, but—alas! no evidence supports it.
Although the ziggurats of Mesopotamia look a little like the pyramids of Egypt, there is no reason to think that there is any real connection between the two types of structure. The ziggurats evolved from temple platforms, whereas the Egyptian pyramids were never anything but tombs.
The seeming similarity of Mesopotamian ziggurats to Egyptian pyramids, and for that matter to the pyramids of Central America, is explained by the state of engineering in these lands when these structures were made. If you set out to build an edifice several hundred feet high when architecture is in its infancy, the arch and vault are practically unknown, and metal reinforcement is undreamed-of, you have to adopt a pyramidal form for the sake of stability.
In —XII, this teeming farmland with its web of blue canals and its looming ziggurats resounded to the tramp of the dreaded soldiery of Assyria—burly, bearded, hooknosed men in heavy boots and crested bronzen helms. For 500 years, one of the most ferociously militaristic governments known to history held the Land Between the Rivers in its merciless grip. Assyrian kings were always putting up monuments boasting:
I destroyed them, tore down the wall, and burned the town with fire; I caught the survivors and impaled them on stakes in front of their towns . . . Pillars of skulls I erected in front of the town ... I fed their corpses, cut into small pieces, to dogs, pigs, vultures ... I slowly tore off his skin ... Of some I cut off the hands and limbs; of others the noses, ears, and arms; of many soldiers I put out the eyes ... I flayed them and covered with their skins the wall of the town . . ,12
