TUNNEL LINERS WAIT ASSEMBLY ON THE SITE HI i T Aur, .-., IT .' :.Ibrj rAr. THIE LI' TH e F rhni U .I P i:,' 1I.1A A'MILE THE C-4.,I A 15- r.:'. I.ILT
AN AUTOMOBILE coming off the assembly line represents the expendi-
ture of at least 30,000 gallons of water-20,000 needed to produce its
ton of steel, and 10,000 more used during the actual assembly process.
Many thousands more are involved in the manufacture of its plastics,
glass, fabrics and other parts. Every gallon of gasoline poured into the
tank may represent as much as another 70 gallons of water, utilized
Statistics like these could be prepared for every amenity of civilized
society-for the food we eat, the clothes we wear, even the books we
read and the television we watch. For water is the lifeblood of industry,
its most essential material. No other substance except air flows in such
volume through the factories of the industrialized world. Water is a
source of power, either directly in hydroelectric plants, or indirectly as
steam. It supplies the warmth that radiates from many heating sys-
tems, and in steel mills its coolness quenches glowing metal. It is a
raw material in chemicals, beer, pharmaceuticals and hundreds of
other products. It is the solvent in which chemical reactions take place
in the manufacture of bleaches, and it washes impurities from pulp in
paper mills. Via streams and rivers, it carries off many thousands of tons
of industrial waste daily.
All these uses-plus many more-are possible because of water's chem-
ical and physical properties, such as its heat capacity and solvent power.
Since early in history, men have put these properties to work. And
to make them work more efficiently, they have created ever more in-
genious devices, for water has long been a mother of inventions.
The earliest way of employing water was to pour it upon a field for
irrigation. This could be hard work, but in Mesopotamia by the Third
Millennium B.C., and later in Egypt, farmers found a way to make the
job easier-by combining human sinew with a simple lever machine
called the shaduf, still widely used in the Orient and the Middle East.
The shaduf was a beam resting in a notch atop a broad post. A leather
bucket hung from one end of the beam, and a counterweight was at-
tached to the other. After the farmer had dipped the bucket into a
stream, the counterweight helped him to lift the bucket high enough to
dump the water into a ditch running among his crops. Crude as it was,
the shaduf enabled a man to raise 600 gallons of water a day to a height
of six feet much more easily than he could by muscle power alone.
Centuries later, some genius hit upon the idea of lifting water by
means of pots fastened about the rim of a vertical wheel. As the wheel
revolved, turned by one or more men walking a treadmill attached to
its shaft, one pot after another scooped up water, raised it, and spilled
it into the irrigation ditch. An adaptation of this device-an endless
chain carrying buckets-may have been used to water the Hanging Gar-
dens of Babylon in the Sixth Century B.C.
Later still, Archimedes of Syracuse (287-212 B.C.), one of the great
scientific intellects of all time, is believed to have invented the water
screw which bears his name. In principle similar to the modern kitchen
ARCHIMEDES' PUMP was presumably
invented by the Greek geometer in the Third
Century B.C.. and was used for irrigation.
The pump consisted of a hollow wooden tube
within which there was a spiral screw thread
wound around a central pole (cutaway above).
Cranked by hand, it raised water from a
river to a field above it. The Nile delta has been
irrigated with such devices for centuries.
meat grinder, Archimedes' screw consisted of thin wooden strips coiled
on edge in a spiral around a rod and tightly encased in a wooden tube.
One end of the tube was immersed in the stream, the other angled up
to rest on the lip of an irrigation trench. The farmer spun the whole
thing with a hand crank. As the tube revolved, water was trapped in
each turn of the screw and raised until it spilled out at the top. The
Romans called Archimedes' invention a cochlea (snail), and used it to
drain their tin mines in Britain. In some Mediterranean countries, farm-
ers still spin a modification of the water screw.
Water to mark the hours
These were prosaic devices to transport water where man wanted it.
Other inventions were more exotic. There was, for instance, the water
clock, or clepsydra, probably first used in ancient Egypt. This was a
jar with one or several holes in its bottom. The time it took for a
given amount of water to drip completely out of the jar became a meas-
uring unit. In the courts of early Greece, speeches were limited by such
a clock-time ran out when the water ran out. With this primitive sys-
tem, it was easy enough to measure a jarful of time, but determining
intermediate intervals was difficult since the water did not flow at a
constant rate. When the jar was full, it leaked out faster because the
water pressure was high. As the water level decreased, so did the pres-
sure, and the leak slowed to a leisurely drip.
The problem of reckoning intermediate time intervals was solved
around 250 B.C. by Ctesibius, a Greek barber-turned-engineer. Ctesibius
built a clepsydra that transformed a slender stream of water into a
stream of time. His timekeeper consisted of three vessels. The first was
the source of water. Through a hole in its bottom, water dripped into a
second vessel in which the water level was kept constant by an overflow
outlet partway up the vessel's side. Another outlet in the bottom of the
vessel released water at a uniform rate into the third vessel. The sides
of this third vessel could be marked off in graduated units on which the
rising water level indicated the time.
Eventually clepsydras became elaborate affairs involving gears, wheels
and shafts. The Roman architect-engineer Vitruvius, in his celebrated
work De architectural, written about 25 B.C., told of one such clock in
which "figures are moved, cones revolve, pebbles or eggs fall, trumpets
sound, and other incidental effects take place."
In the First Century A.D. the first clue to the use of water for steam
power was uncovered by.another Greek mechanical genius, Hero of
Alexandria. Hero, whose inventions ranged from a bellows-operated or-
gan to a coin-in-the-slot holy-water dispenser, produced the aeolipile-
a hollow sphere partially filled with water and suspended between two
pivot-supports over a fire. When the water boiled, tubes on either side of
the sphere, their openings bent to face in opposite directions, emitted
jets of steam. The reaction to the jets, like the reaction to the blast
from a modern rocket engine, caused the sphere to whirl furiously. Al-
though Hero's toy was the first steam engine, its inventor put it to no
The truly epoch-making hydraulic inventions of antiquity, however,
were those that first harnessed the energy inherent in falling water.
The simplest waterwheel, probably invented for milling grain in the
Near or Middle East about the First Century B.C., had a series of paddles
fanning out from a vertical shaft, like a wheel laid on its side. The
shaft passed upward through a hole in a fixed, horizontal millstone and
was fastened to a movable millstone on top. Such a mill was usually
built at the edge of a swift stream so that some of its paddles extended
into the current. The current, pushing against the paddles, turned the
shaft and the upper millstone. Grain placed between the stones was
ground to flour, but the grinding was a slow process-one revolution
of the waterwheel meant one revolution of the millstone. But slow as
they were, such primitive mills served man for two millennia. One was
still operating in the Shetland Islands off northern Scotland as late as
the 1930s. This type of mill, widely used in the fast-running streams
of Northern Europe, became known as the Norse mill.
Wheels that crush grain
Far more efficient was the waterwheel named after Vitruvius, the
same Roman author who described the water clock. The Vitruvian
wheel was the waterwheel of the Norse mill turned on edge and mounted
on a horizontal axle. It was what engineers call an undershot wheel-it
revolved as water flowing under it struck the low paddles. A large gear
on the wheel's horizontal axle engaged a smaller gear on the vertical
millstone shaft. The rotary motion of the axle was thereby transmitted
to the millstone so that it turned several times with each revolution of
the waterwheel. Thus the Vitruvian mill was capable of producing more
flour-and producing it faster-than the Norse mill.
All waterwheels are turned by the energy of descending water, and
the theoretical maximum energy available for the job depends only on
the height through which the water descends. When this drop occurs
gradually, as it must in a stream supplying a Norse or undershot wheel,
much of the theoretically available energy has been dissipated in friction
before the water reaches the wheel. If the water can make all or most of
its descent right at the wheel itself, more energy will be available for
use. In addition, the descending water will be in contact with the pad-
dles for a greater distance than in the case of an undershot wheel; thus
more of the available energy will be applied to the motion of the wheel.
By late Roman times these facts were recognized by some unknown en-
gineer, and he introduced the overshot wheel-one turned by water that
poured down on the upper paddles through a sluice leading from a dam
at a higher level.
As long as manpower-especially slave labor-was plentiful, there was
little incentive to develop water power extensively. But when Europe
began to emerge from the Dark Ages that followed the collapse of the
STEAM FROM BOILER
*-4 l -
STEAM POWER, introduced in the 18th
Century, utilized water's tendency to expand
when heated. In the reciprocating steam engine
above, the flywheel is operated by the thrusts
of a piston that is driven back and forth
by steam entering the cylinder from a boiler.
A valve is moved back and forth by the
flywheel; its purpose is to direct the steam
alternately to the two sides of the piston.
Roman Empire and entered a period of economic growth, water power
became increasingly important to its expanding industries. The Domes-
day Book, written in 1086 by order of William the Conqueror to record,
among other things, the economic resources of England, lists 5,624 wa-
ter mills-one for about every 400 inhabitants.
Soon waterwheels were being used for a wide variety of industrial
purposes besides grinding grain. They powered machines to saw wood,
spin silk, chop rags for papermaking, beat hides for tanning. They
pumped the bellows for early blast furnaces. They ran trip-hammers to
crush ore and shape metal. They turned polishing machines for armorers
and, later, boring machines for gunsmiths. A 19th Century giant, 721/2
feet in diameter, developed 200 horsepower to drive a mine-draining
pump on the Isle of Man in the Irish Sea.
The steam revolution
"By the middle of the 18th Century," the American historian and critic
Lewis Mumford has pointed out, "the fundamental industrial revolu-
tion... had been accomplished: the external forces of nature were har-
nessed and the mills and looms and spindles were working busily through
Western Europe." The chief force of nature thus employed was water.
But it was now beginning to be used in a completely different way: as
steam. It was the harnessing of water, not simply as a falling weight, but
as a substance with amazingly useful heat properties that brought on the
Industrial Revolution as we think of it today.
The steam engine works as well as it does precisely because of the
peculiar physical properties of water. For one thing, water becomes
steam at a moderate temperature, a temperature low enough to have
been within the capabilities of 17th and 18th Century machine builders.
But most important is water's ability to absorb heat. A very large quan-
tity of heat energy is needed to raise the temperature of water a given
number of degrees or to change it from a liquid to a gas. Conversely, the
change from gas to liquid releases a great amount of heat energy. This
energy is the source of the work done by a steam engine; it is converted
into mechanical energy to drive pumps, turn wheels and operate looms.
The heat energy that water (or any substance) absorbs increases the
motion of its molecules. The more heat, the faster the molecules jump
around. At a certain speed-i.e., at a certain temperature-they jump
so fast that they overcome the forces that link them together: the liquid
boils and becomes a gas. Breaking such a link requires a great amount
of energy; at this point the energy is absorbed simply to cause the trans-
formation without increasing temperature. This change from liquid into
gas is accompanied by a sudden increase in volume. When water boils
into steam, it expands some 1,600 times. Further heating increases the
molecular motion still more, causing even greater expansion.
The first crude engine to utilize the expansion created when water
changes to steam was invented in 1690 by Denis Papin, a French Hugue-
not physicist living in England. Papin put a small amount of water into
a tube about two and a half inches in diameter that was closed at the
bottom and fitted with a snug piston. When he brought the water to a
boil, the expanding steam forced the piston to the top of the tube, where
a catch secured it. Then Papin cooled the tube, and the steam con-
densed into the original volume of water, leaving a partial vacuum in
the tube. When the catch was released, the outside air pressure drove
the piston back with a snap.
A few years later, a military engineer named Thomas Savery, sitting in
a tavern on the Cornish coast, was startled to see a cork being sucked
into a bottle half full of steaming hot water. A few experiments showed
him that when bottles of steaming water were set in a cool place, the
corks were always pulled in as the steam condensed. Savery then built
this principle into a crude steam pump that managed to drain water
from several mine pits. The pump consisted of two parts which operated
alternately. Each part was made up of a closed, barrel-shaped vessel
equipped with valves and two pipes. When one vessel was filled with
steam from a boiler, then suddenly cooled with a dash of cold water,
the steam condensed, creating a partial vacuum in the vessel. Through
a pipe leading from the vessel to the drainage pit of the mine, water was
sucked up into the vessel. When the steam was turned on again, the wa-
ter was forced upward through an outlet pipe. Then the process was re-
peated. Because its lifting power was inadequate, Savery's pump was
never widely used.
A mechanical seesaw
In 1705 Thomas Newcomen, a Devonshire ironmonger and smith, built
the first practical steam engine, again for use in the mines. Newcomen
combined Savery's separate boiler with Papin's moving piston and cyl-
inder and added an idea of his own, a huge wooden crossbeam-a seesaw
arrangement with one end connected to a counterweight and a pump rod
extending down in the mine, the other end attached to the piston in the
cylinder. When steam was forced into the cylinder, the piston was raised
to the top. Then, from a separate water tank, cold water was piped
into the cylinder to cool the steam. As the steam condensed into water, a
partial vacuum formed in the cylinder and atmospheric pressure drove
the piston back, as the cork was drawn into Savery's bottle of cooling
water. When more steam was forced into the cylinder, the piston moved
up again and the cycle was repeated, rocking the beam up and down, to
operate the pump and drain the mine. This engine did not make full use
of the tremendous power of expanding steam-but it was the first ma-
chine with moving parts driven partly by steam, although it also utilized
the pressure of the atmosphere.
The atmospheric pump was useful but expensive, requiring mountains
of coal to keep it running. The man who solved this problem was James
Watt, a young instrument maker for Glasgow University. While repairing
a Newcomen engine one day in 1763, Watt began to wonder why it re-
quired so much fuel. It was obvious that less fuel would be needed if
the cylinder did not have to be heated and cooled over and over again
-that is, if it could be kept constantly as hot as the steam coming into
it. If the steam could be transferred to a separate chamber before it was
condensed, there would be no need to cool the cylinder at all. Watt first
tested his idea on a small model, using a surgeon's 10-inch brass syringe
as cylinder-and-piston. In a later, improved version of his engine, he
insulated the cylinder in an outer casing that could be filled with steam,
to keep the cylinder constantly hot. Then he rigged up a separate cham-
ber kept cool by cold water. When the steam from his boiler filled the cyl-
inder, it forced its way through a tube into the cooling chamber, where
it condensed into water. Meanwhile, the expanding steam drove the pis-
ton in the cylinder.
Watt caused this transformation from steam into water to occur out-
side the cylinder, thereby making it possible for the cylinder to be kept
hot and the condenser cool at the same time. But engineers who fol-
lowed him concentrated on getting more and more energy from the ex-
pansion of steam by heating it to higher and higher temperatures; this
way it could expand more, and perform more work.
Watt devised a way of introducing steam at both ends of the cylinder
alternately, thereby getting two power strokes where before there had
been only one. (Later came the double-expansion engine, and even tri-
ple- and quadruple-expansion engines, in which steam from a first cyl-
inder was led to a second and allowed to continue expanding, putting
still more of its energy to work.)
A nation "steam mill mad"
Finally, prodded by his business partner, Matthew Boulton, who wrote
to him in 1781 that "the people of London, Manchester, and Birmingham
are steam mill mad," Watt contrived a practical mechanical linkage that
would convert the up-and-down motion of the reciprocating steam en-
gine into rotary motion. At last the steam engine was ready to fulfill its
role as the prime mover of 19th Century industry and transportation.
Today the steam piston engine has been largely replaced by the steam
turbine, invented in 1882 by a Swedish engineer, Carl Gustaf Patrik de
Laval, who was looking for a device to spin a high-speed cream separator.
Laval was a specialist in the design of nozzles, and he knew that the
steam jet from one of his sandblasting nozzles could spin the entire sand-
blasting machine. This was the germ of his idea.
All turbines are bladed wheels. Like the steam piston engine, a steam
turbine stores heat energy and releases it in a usable form as the steam
expands and cools. In the modern turbine, expanding steam is squirted
from nozzles to rotate a wheel rimmed with blades. The blades are so
shaped that the steam leaves them in a high-velocity jet. The impact of
the entering steam striking the turbine helps to turn the wheel, much as
water striking the paddles turns a waterwheel, but it is the reaction to
the departing steam-the kickback-which provides the major driving
force. Then the steam passes through a ring of stationary blades which
serve to squirt it in jets against another rotor. The process is repeated,
with the steam expanding at each step until the last available energy
has been wrested from it.
There are water turbines, too. Like the overshot waterwheel which
first turned millstones in the closing years of the Roman Republic, these
exploit the energy released by falling water. As the steam turbine de-
rives its major driving force from reaction to exiting steam, so many water
turbines get their chief power from the exiting stream of water.
Because turbines produce smooth rotary motion they are particularly
suited to the generation of electricity. Some 30 years after the dynamo
was invented in 1831, water was harnessed to the work of driving it
with a reciprocating steam engine. Today, steam or water turbines per-
form this job.
Power from harnessed water
Predictably, the first large hydroelectric power plant in the United
States was built at Niagara Falls, in 1895. By 1965, more than 1,500
hydroelectric plants were helping to light homes and run factories. Of
the more than one trillion kilowatt-hours of electricity produced for gen-
eral distribution in the United States each year, steam plants provide
79 per cent and hydroelectric plants about 20 per cent (less than 1 per
cent is produced by internal-combustion engines). Together they made
use of some 400 trillion gallons of water in 1965.
One of the most impressive works of modern engineering is a great
dam producing hydroelectric power. Hoover Dam, towering 726 feet
above the bed of the Colorado River between Nevada and Arizona and
backed by its 115-mile-long reservoir of Lake Mead, is a spectacular
example. The most famous dam in the Western Hemisphere-and the
tallest-it attracts thousands of sightseers each year. Elevators from the
top of the dam lower visitors 528 feet into the heart of the vast con-
crete structure-a distance equal to 44 stories in an office building-to
a tunnel connecting with the power plant at the dam's base. Each wing
of the U-shaped plant is as long as two football fields laid end to end
and houses a row of the plant's 17 giant generators. On a level below
the roaring generators are the turbines, spun by water flowing under
tremendous pressure through four main pipes, or penstocks, from Lake
Mead. These penstocks are enormous, each 30 feet in diameter and large
enough to carry a railroad train or two lanes of highway traffic. When
the water has done its work of spinning the turbines and their genera-
IN A STEAM TURBINE, superheated steam
(blue arrows) blasts against vanes attached
to the turbine's shaft, causing the shaft to spin.
The resulting energy may be used for a
variety of purposes, from powering a luxury
liner to operating an electric power plant. The
steam enters a turbine at pressures up to
400 pounds per square inch. but it loses some
pressure within the engine. As it does so
it expands-and the cylinder is made
wide at the far end to allow for the expansion.
EXHAUST FLOW 151
HYDROELECTRIC PLANTS, generating
electric power from dammed-up water.
produce 20 per cent of the U.S. power supply.
Building up behind a high dam, water
accumulates potential energy. This is
transformed into kilowatts when the water
rushes down a sluice and is diverted into the
rotary blades of a turbine (a refined version
of the ancient waterwheel). The turbine's
rotation spins electromagnets which generate
current in stationary coils of wire. Finally,
the current is put through an adjoining
transformer where the voltage is stepped up
for transmission over power lines.
tors to produce electrical energy, it gushes from turbine discharge tubes
at the base of the dam into the churning gorge of the Colorado River.
The huge dams used in producing electricity are usually designed to
serve other needs as well-for example, they store water for irrigating
farmland, and create lakes for fishing and boating. The best-known ex-
ample of such multipurpose planning is the Tennessee Valley Authority,
a government corporation created in 1933 to develop the full potential
of the great Tennessee River system. In addition to generating hydro-
electric power, it helps control erosion, provides recreation facilities and
improves navigation. Its vast system of dams, reservoirs, steam plants
and bridges ranks it among the world's great engineering projects.
A river system revitalized
At the outset, TVA took over the already built Wilson Dam at Muscle
Shoals, Alabama. It has since acquired four other major dams and built
21 new ones. Altogether, these have made the Tennessee River naviga-
ble for 650 miles from Knoxville, Tennessee, to its mouth at the Ohio.
The dams supply electric power over an area of 80,000 square miles.
New and improved fertilizers developed by TVA have helped thousands
of valley farmers to enrich their soil, revitalizing a countryside that was
once among the poorest regions in the United States. Since TVA was es-
tablished, the population of the Tennessee Valley has increased by more
than a million; its per capital income has risen from 45 per cent of the
national average in 1933 to nearly 70 per cent in 1963.
Electric power production was a vital part of the original TVA concep-
tion and remains by far the best known feature of its economic activity.
But the power, at first largely hydroelectric, is now 70 per cent steam-
produced. Much of the increased steam-generating capacity has been
in response to the needs of the government-owned atomic-energy plants
in the TVA area.
TVA's overall benefits have inspired ideas for similar river develop-
ments elsewhere, such as the Volta River Project in Ghana, and Damo-
dar Development in India. Something of the sort also has been under
study since 1957 for the Mekong River basin in Southeast Asia, which
is shared by Laos, Thailand, Cambodia and Vietnam. This 307,000-
square-mile area-a watershed greater than that of the Columbia in
the northwestern United States-is drained by an undeveloped river ris-
ing in Communist China and is inhabited by 20 million people, most
of them rice farmers.
The project calls for four giant dams to harness the Mekong itself for
flood control, irrigation, navigation and hydroelectric power; a network
of smaller hydroelectric dams is planned to tap the river's swift-flowing
mountain tributaries. The proposed major dam at Pa Mong on the Thai-
land-Laos border would create one of the largest storage reservoirs in
the world. Hand in hand with this dam-building project would go an
ambitious program to teach efficient agricultural methods to farmers
and to train construction workers, mechanics and engineers. Full de-
velopment of the Mekong basin is expected to span a century and cost
seven billion dollars.
Although multipurpose projects such as TVA and the proposed Me-
kong River basin development appear to be ideal integrated river-basin
plans, they do have shortcomings. To justify the construction of reser-
voirs, it is often pointed out that they can be made to serve many uses
-but it is rarely recognized that these uses may be competitive. In or-
der to provide flood protection, a reservoir should be kept as empty as
possible so that there will be space to store floodwater when it comes.
For irrigation or water-supply purposes, on the other hand, a reservoir
should be at near-capacity level as insurance against dry periods. Also,
power production is enhanced by a full reservoir because the generation
of power increases or decreases in accordance with the depth of the wa-
ter in storage. Obviously, no one reservoir can serve all of its purposes
The value of scenery
Other shortcomings of multipurpose projects-and those least often
appreciated-are imponderables involving values to society as a whole.
Advanced societies, and the United States in particular, have needs and
desires transcending mere money values. An example of this is the na-
tion's present interest in its natural beauty. Dams and reservoirs can
be evaluated in terms of monetary costs and monetary benefits, but com-
parable yardsticks to measure esthetic value-the existence of unspoiled
scenery, of wilderness solitude, of recreation-do not exist. Neverthe-
less, the value of a contemplated reservoir must be balanced against
the worth of the same area preserved for its esthetic quality. These es-
thetic values are increasing and will continue to increase with scarcity,
particularly in this age of population pressure. The reservoir of Glen
Canyon Dam on the Colorado River in northern Arizona already en-
croaches on the magnificence of Rainbow Bridge National Monument,
and dams for power generation are being contemplated that would alter
the spectacularly beautiful and unique landscape of the Grand Canyon.
One of these would create a man-made lake stretching for 93 miles
through the world-famous river gorge.
Thus great water-development projects can prove both a liability and
a blessing. Efficiently conceived, they can bring prosperity and well-
being to vast areas of the world. Improperly planned, they can create
problems that may more than outweigh their benefits.
If man had been content to leave water where nature put
it, his civilization might have stopped growing long ago.
Instead he has stored water in reservoirs, converted its
energy into electricity, channeled it into canals, moved it
great distances to irrigate farms, employed it in industrial
processes and pushed it back with dikes to gain more land.
The process of controlling the earth's water has driven
man to undertake the largest of all his engineering projects.
The two-mile-long Aswan High Dam on the Nile-120 mil-
lion tons of granite rock, sand and concrete that will back
up a lake more than 300 miles long-is expected to double
Egypt's power production. Irrigation conduits in Israel car-
ry water 70 miles to make a desert bloom. A navigation ca-
nal in China stretches 1,000 miles; the mighty locks of the
Panama Canal lift cargo ships over an 85-foot-high ribbon
of land that separates oceans. In France, a new type of
dam has been designed to harness the flow of the tide. The
scope of water-control engineering is constantly expanding
to meet the needs of growing populations. Every month,
another major dam is completed somewhere in the world.
DETOUR FOR A RIVER
Before concrete could be poured for the Bhakra Each of the tunnels carried water half a mile at
Dam in India, two tunnels 50 feet in diameter the rate of five feet per second. When the dam
had to be bored through solid rock around both was completed, the two tunnels were plugged
sides of the damsite to divert the river's flow. with several hundred thousand tons of concrete.
Dams, the biggest of all man-made
structures, are designed to serve a
number of purposes: they back up
reservoirs for irrigation, store mu-
nicipal water, produce electric pow-
er, improve navigation and protect
against floods. Most dams hold back
water by their sheer weight. Known
as gravity dams, they can be made
of earth, rock or concrete. Another
type of dam, used especially in nar-
row gorges, employs the structural
strength of an arch, in addition to
weight, to hold back rivers.
Dams are breeders of impressive
statistics. The Shasta Dam (right)
in Northern California cost $142 mil-
lion and required as many as 3,600
workers at one time. Even before it
could be built, workmen had to con-
struct a cofferdam and drill a chan-
nel through solid rock to divert water
around the dam's site. Twelve mil-
lion tons of sand and gravel for con-
crete were brought nine and a half
miles by conveyor belt from a quarry.
The completed dam holds back a wa-
ter pressure of 30,000 pounds per
square foot at its 541-foot-thick base.
A BULWARK FOR THE SACRAMENTO
The Shasta Dam is a concrete structure 602
feet high-more than three times as high as
Niagara Falls-and measures two thirds of a
mile across its crest. Completed in 1945, it
generates enough electricity for a city of 500,-
000, but its main function is irrigation. The
water it backs up is dispersed into channels
stretching 500 miles to the south, irrigating
more than a million acres of California farmland.
If rainfall in a warm climate averages
less than 20 inches a year, the land
cannot be farmed for most crops un-
less it is irrigated. Although such re-
gions may lie hundreds of miles from
a river, they can be made to bloom
through the agency of modern engi-
neering. A single dam on the Yangtze
River in China is designed to disperse
water to 10 million arid acres. Many
irrigation projects, such as that of the
Central Valley in California (left), re-
ceive their water via broad concrete
canals. Sometimes the water is trans-
ported by pipelines or along stone
aqueducts (far left).
Irrigation takes nearly half of all
the water that is presently used in
the United States. The government-
financed construction of irrigation
systems (partly repaid by water us-
ers) has put approximately eight mil-
lion acres of arid land under cultiva-
tion. However, irrigation also poses
a serious problem. Nearly 97 per cent
of the water for houses or factories is
flushed back into rivers and can be
treated and reused. But in irrigation,
almost all the water is lost-through
evaporation, transpiration by plants,
and seepage through canal beds
which are not lined with concrete.
CARRYING WATER TO NEEDY SOIL
Curving through the Central Valley, an irriga-
tion canal brings a heavy flow of water from the
reservoir behind Shasta Dam. Once a barren
area where cactus and sagebrush grew, the
Valley now produces 80 per cent of the nation's
grapes, one third of its fruit and one quarter
of its vegetables-in all, 220 crops are raised.
Defenses for a
On February 1, 1953, under the on-
slaught of wind-whipped waves from
the North Sea, dikes protecting the
southwestern Netherlands burst in
100 places. Some 400,000 acres were
flooded and 1,800 people drowned.
The catastrophe, one of the worst
in Dutch history, was a nation's an-
cient nightmare come true-for the
Netherlands exists in the very maw of
the sea, and the threat of a flood dis-
aster is always present. A tiny coun-
try with the densest population in
the world, the Netherlands has been
adding to its own land since the 12th
Century by constructing an artificial
coastline of dikes, then pumping out
the impounded seawater with wind-
mills and electric pumps. Today fully
half of the Netherlands, including the
two largest cities, lies below the level
of the sea. An altimeter at the Am-
(1) In 1956 work begins on a dike across a Netherlands esluary
(3) As a crowd cheers from the shore, the final concrete caisson,
(2) Boats lay asphalt to hold down the sand at ihe dike's base.
sterdam airport reads -13 feet; near
Rotterdam it reads 30 feet.
The Netherlands' defenses against
the North Sea require constant main-
tenance by a corps of 10,000 engineers
and workers. Day and night, 2,000
pumps and 400 windmills labor to
keep the land dry. The Netherlands
allots 8 per cent of its national budg-
et for dike-building and upkeep.
In many places the dikes are bat-
tered and antiquated. After the 1953
flood, the Dutch government under-
took a huge $650-million, 25-year con-
struction program to prevent any re-
currence of the disaster. About 25
miles of new concrete dikes are being
built across the mouths of estuaries
in the southwest part of the country.
These new barriers will form an out-
er wall to protect the vulnerable old-
er dikes, and will shorten the coast-
line of the Netherlands by 435 miles.
This project may keep the Dutch
safe for many centuries, but it does
not mark the end of their daring engi-
neering ventures. One far-reaching
scheme now being considered would
pump 600 billion cubic yards of earth
into the interior of the country from
the North Sea-and, by raising the
sunken nation above the waves, end
the threat of the sea for all time.
(4) A buffer of concrete is laid on both sides of the caisson core.
weighing 170 tons, is floated in to close the gap. It will be sunk with sand. (5) The dike is completed after 65 months and topped by a road.
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A ROUTE INTO A CONTINENT
Ships crowd a flight of locks on the Welland
Canal of the St. Lawrence Seaway. These locks,
consisting of two massive steel gates 859 feet
apart, can lift or lower a ship 138 feet. In the
lifting process, the downstream gate is swung
open and the other remains closed as the ship
enters. Then the gates reverse position and wa-
ter pours into the lock, slowly raising the ship.
LINK BETWEEN SEAS
Half hidden by dunes, an ocean liner makes the
100-mile run through the sea-level Suez Canal.
The Canal was completed in 1869 after 10
years of work. A current runs through the Canal,
carrying certain species of Red Sea fish into the
Mediterranean Sea. Flourishing there, they now
threaten extinction for some native fish species.
Canals today bear more traffic than
ever before-for the cheapest way to
ship bulk cargo is still by water. The
booming industrial sections of Ger-
many, France, Belgium and the Neth-
erlands depend on a 13,000-mile net-
work of barge canals and rivers. The
Great Lakes ports, benefiting from
the access to the Atlantic provided by
the $1.3-billion St. Lawrence Seaway,
now handle 70 per cent as much car-
go as all other U.S. ports combined.
The titans among canals are the
lockless Suez-35 feet deep and 165
yards wide-and the six-lock Panama
Canal. The Suez provides passageway
for 40 ships a day between the Medi-
terranean and the Red Sea. Traffic
on the Panama waterway has reached
1,000 ships a month-and plans for
a second canal across Central Amer-
ica are receiving serious attention.
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U.S. industry requires 32 billion gal-
lons of water a day, about 20 billion
more than are used in households.
About two thirds of industrial water
is used for cooling. One Celanese Cor-
poration plant, for instance, uses
160,000 gallons of water a minute to
cool petrochemical products. Water
S functions as a solvent in chrome-plat-
'- ing processes, and as a cleansing
agent in the processing of coal. Water
may also be the source of a product:
magnesium is extracted from the sea
(left). Water is used for mining: in the
operation shown at left below, super-
heated water melts and forces sulfur
T out of the ground.
Many factories also employ water
to carry off refuse (industrial waste
is a common pollutant of rivers). On
the other hand, some plants actually
put polluted water to use. The Beth-
lehem Steel plant in Maryland uses
150 million gallons a day of effluent
from Baltimore's sewage-treatment
plant, cooling its hot steel with wa-
ter that has already served the city.
MINING MAGNESIUM IN THE SEA
Practically all of U.S. magnesium is chemically
gleaned from seawater in the giant vats of a
Texas plant. Seawater contains dissolved mag-
nesium chloride, which is changed to magnesi-
um hydroxide when lime is added. This is then
processed to produce the lightweight metal.
MINING SULFUR WITH WATER
In a technique that employs water heated to
330" F., two million tons of sulfur are forced
from the ground of Texas oil country each year. V J
Pumped into the earth at extremely high pres-
sure.thewater liquefies the solid sulfur and helps
bear.it up to the surface through an exit pipe.
COOLING MOLTEN STEEL
India's great Tata Works, located 140 miles
from Calcutta on the bank of a river, uses al-
most 5.000 gallons of water to process each
ton of steel. The water, sprayed on the white-
hot steel after it leaves the factory's blast fur-
naces, is recirculated and cooled for further use.
AN EXIT THROUGH THE DAM
A maintenance worker makes his way around
an unused "scroll case" at the base of the dam.
Connected to the upriver side of the dam by a
tunnel, the scroll case encircles the horizontal-
ly positioned turbine wheel (far right), deliver-
ing water to the blades at a uniform velocity.
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A swirling current races from the turbine at the
FIRST STEP TO ELECTRICITY
Two steam turbine wheels. 12 feet in diameter,
are given a last-minute inspection at a General
Electric plant in Schenectady. New York. The
turbines installed in dams are far larger: their
weight is measured in hundreds of tons, and the
wheel casings are sometimes 65 feet across.
base of Wheeler Dam. part of the Tennessee Valley Authority system. The massive cylinders in the background house the dam's generators.
Power from a
One fifth of the electric power used
in the U.S. is generated by water held
behind dams, and almost all of the
rest comes from water that is heated
for steam generators. Hydroelectric
dams work on a simple principle: the
greater the vertical distance between
water backed up behind a dam and
the turbine blades at the base of the
dam, the more power is generated.
The turbines are connected by a drive
shaft to a generator overhead; some
can deliver as much as 300,000 horse-
power to the whirling electromagnets
where current is produced. Hydro-
electric projects, like the Grand Cou-
lee and Hoover Dams, are engineer-
ing monuments. But their construc-
tion can be controversial. There is
strong opposition from conservation
groups, for example, to a proposed
power dam inside the Grand Canyon.
A Dam to Draw
Power from the Sea
Tides vary widely in different parts
of the world. In a few places they run
to extremes, with variations of 20
feet or more between high tide and
low. This height difference, with its
resulting water flow, is sufficiently
great to be harnessed for the pro-
duction of hydroelectric power. Con-
struction began in 1961 on the world's
first tidal-power dam, near the mouth
of the Rance estuary on the coast of
France. Twice a day, a tidal flow
nearly equivalent to that of the Mis-
sissippi River will pour through the
dam's 24 turbines and raise or lower
the water level 28 feet. The turbines
are designed to generate 240,000 kilo-
watts of electricity when the tide is
flowing in and the same amount when
it is ebbing out. Because this amount
is not always adequate to meet the re-
gion's power needs, the blades of the
turbines-driven by electricity from
nearby steam generators-can slowly
pump water into the reservoir dur-
ing periods of slack tide. The stored
water can then be released to gener-
ate power at times of peak demand.
A GATEWAY FOR TIDAL ENERGY
The pump-turbine fixture above is the key to
the Rance dam's versatility. It can drive a gen-
erator when the water flows through in either
direction. It can also function as a motorized
pump-its blades acting as a propeller to push
water back into the reservoir when the tide is
slack. The dam itself, hard by the city of St.-
Malo, includes a lock (far left) for small boats.
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