This is one of the oldest branches of engineering, and was developed
before the last century. The irrigation works of Asia, Africa, Spain,
Italy, the Roman aqueducts, and the canals of Europe, are examples.
Hydraulic works cannot be constructed in ignorance of the laws which
govern the flow of water. The action of water is relentless, as ruined
canals, obstructed rivers, and washed-out dams testify.
The principal additions of the nineteenth century to hydraulic
engineering are the collection of larger statistics of the flow of
water in pipes and channels, of rainfall, run-off, and available
supply. It is now known that the germs of disease can be retained by
ordinary sand filters, and it is now an established fact that pure
drinking water and proper drainage are a sure preventive of typhoid and
similar fevers. Very foul water can be made potable. Experiments show
that the water of the Schuylkill River at Philadelphia, which contains
400,000 germs in the space of less than a cubic inch, was so much
purified by filtering that only sixty remained. This is a discovery
of sanitary science, but the application of it is through structural
engineering, which designs and executes the filter beds with great
economy.
The removal of sewage, after having been done by the Etruscans
before the foundation of Rome, became a lost art during the dirty
Dark Ages, when filth and piety were deemed to be connected in some
mysterious way. It was reserved for good John Wesley to point out that
“Cleanliness is next to godliness.” Now sewage works are as common as
those for water supply. Some of them have been of great size and cost.
Such are the drainage works of London, Paris, Berlin, Boston, Chicago,
and New Orleans. A very difficult work was the drainage of the City of
Mexico, which is in a valley surrounded by mountains, and elevated only
four to five feet above a lake having no outlet. Attempts to drain the
lake had been made in vain for six hundred years. It has lately been
accomplished by a tunnel six miles long through the mountains, and a
canal of over thirty miles, the whole work costing some $20,000,000.
The drainage of Chicago by locks and canal into the Illinois River has
cost some $35,000,000, and is well worth its cost.
Scientific research has been applied to the designing of high masonry
and concrete dams, and we know now that no well-designed dam on a good
foundation should fail. The dams now building across the Nile by order
of the British government will create the largest artificial lakes
in the world. The water thus stored will be of inestimable value in
irrigating the crops of Lower Egypt. Their cost, although great, will
not exceed the sums spent by the lavish Khedive Ismail on useless
palaces, now falling to decay.
The Suez Canal is one of the largest hydraulic works of the last
century, and is a notable instance of the displacement of hand labor
by the use of machinery. Ismail began by impressing a large part of
the peasant population of Egypt, just as Rameses had done over 3000
years before. These unfortunate people were set to dig the sand with
rude hoes, and carry it away in baskets on their heads. They died
by thousands for want of water and proper food. At last the French
engineers persuaded the Khedive to let them introduce steam dredging
machinery. A light railway was laid to supply provisions, and a small
ditch dug to bring pure water. The number of men employed fell to
one-fourth. Machinery did the rest. But for this the canal would never
have been finished.
The Panama Canal now uses the best modern machinery, and the Nicaragua
Canal, if built, will apply still better methods, developed on the
Chicago drainage canal, where material was handled at a less cost than
has ever been done before.
Russia is better supplied with internal waterways than any other
country. Her rivers rise near each other, and have long been connected
by canals. It is stated that she has over 60,000 miles of internal
navigation, and is now preparing the construction of canals to connect
the Caspian with the Baltic Sea.
The Erie Canal was one of very small cost, but its influence has been
surpassed by none. The “winning of the West” was hastened many years
by the construction of this work in the first quarter of the century.
Two horses were just able to draw a ton of goods at the speed of two
miles an hour over the wretched roads of those days. When the canal
was made these two horses could draw a boat carrying 150 tons four
miles an hour. Mud, or, in other words, friction, is the great enemy
of civilization, and canals were the first things to diminish it, and
after that railways.
The Erie Canal was made by engineers, but it had to make its own
engineers first, as there were none available in this country at that
time. These self-taught men, some of them land surveyors and others
lawyers, showed themselves the equals of the Englishmen Brindley and
Smeaton, when they located a water route through the wilderness, having
a uniform descent from Lake Erie to the Hudson, and which would have
been so built if there had been enough money.
The question now is whether to enlarge the capacity of this canal by
enlarging its prism and locks, or to increase speed and move more boats
in a season by electrical appliances. The last method seems more in
line with those of the present day.
There should be a waterway from the Hudson to Lake Erie large enough
for vessels able to navigate the lakes and the ocean. A draft of
twenty-one feet can be had at a cost estimated at $200,000,000.
The deepening of the Chicago drainage canal to the Mississippi River,
and the deepening of the Mississippi itself to the Gulf of Mexico, is a
logical sequence of the first project. The Nicaragua Canal would then
form one part of a great line of navigation, by which the products
of the interior of the continent could reach either the Atlantic or
Pacific Ocean.
The cost would be small compared with the resulting benefits, and some
day this navigation will be built by the government of the United
States.
The deepening of the Southwest Pass of the Mississippi River from six
to thirty feet by James B. Eads was a great engineering achievement. It
was the first application of the jetty system on a large scale. This is
merely confining the flow of a river, and thus increasing its velocity
so that it secures a deeper channel for itself.
The improvement of harbors follows closely the increased size of ocean
and lake vessels. The approach to New York harbor is now being deepened
to forty feet, a thing impossible to be done without the largest
application of steam machinery in a suction dredge boat.
The great increase of urban population, due to steam and electric
railways, has made works of water supply and drainage necessary
everywhere. Some of these are on a very grand scale. An illustration of
this is the Croton Aqueduct of New York as it now is, and as it will be
hereafter.
This work was thought by its designers to be on a scale large enough
to last for all time. It is now less than sixty years old, and the
population of New York will soon be too large to be supplied by it.
It is able to supply 250,000,000 to 300,000,000 gallons daily, and its
cost, when the Cornell dam and Jerome Park reservoir are finished, will
be a little over $92,000,000.
It is now suggested to store water in the Adirondack Mountains, 203
miles away, by dams built at the outlet of ten or twelve lakes.
This will equalize the flow of the Hudson River so as to give
3,000,000,000 to 4,000,000,000 gallons daily. It is then proposed to
pump 1,000,000,000 gallons daily from the Hudson River at Poughkeepsie,
sixty miles away, to a height sufficient to supply the city by gravity
through an aqueduct. This water would be filtered at Poughkeepsie, and
we now know that all impurities can be removed.
If this scheme is carried out, the total supply will be about
1,300,000,000 gallons daily, or enough for a population of from
12,000,000 to 13,000,000 persons. By putting in more pumps,
filter-beds, and conduits, this supply can be increased forty per
cent., or to 1,800,000,000 gallons daily. This water would fill every
day a lake one mile square by ten feet deep. This is a fair example
of the scale of the engineering works of the nineteenth and twentieth
centuries.
By the application of modern labor-saving machinery, the cost of this
work can be so far controlled that the cost to the city of New York per
1,000,000 gallons would be no greater than that of the present Croton
supply.
All works of hydraulic engineers depend on water. But what will happen
if the water all dries up? India, China, Spain, Turkey, and Syria have
suffered from droughts, caused clearly by the destruction of their
forests. The demand for paper to print books and newspapers upon, and
for other purposes, is fast converting our forests into pulp. We cannot
even say, “After us the deluge,” for it will seldom rain in those evil
days. When the rains do come, the sponge-like vegetation of the forests
being gone, the streams will be torrents at one time of the year and
dried up during the rest, as we now see in the arid regions of the West.