Modern designs place sluices in the gate sills or in the chamber's floor or walls. A lock may also be equipped with a submerged bubbler that releases air below the gate closure area; the resulting gentle turbulence keeps the area clear of debris that might prevent the gate from sealing properly. Various gate designs are available for modern locks, and different types may be used on the upstream and downstream ends of a single lock.
Miter gates are one of the most popular choices. Another common choice is the Tainter gate, a curved plate that rotates vertically.
In this efficient design, which is used for valves in water-transfer culverts as well as main lock gates, water pressure actually assists in the gate's rotation. Flat gates that slide up, sideways, or down into the lock floor are other options, as are flat gates that are hinged at the bottom and curved gates that rotate horizontally into wall recesses.
William Crawford Gorgas William C. Gorgas was born October 3, , near Mobile, Alabama. In Gorgas received a bachelor of arts degree from the University of the South.
Desiring a military career he decided to enter the Army with a medical degree. Army in June Tours of duty followed in Texas and North Dakota, with nearly 10 years at Fort Barrancas in Florida—Gorgas was assigned this yellow fever area because he had previously had the disease and was immune.
After Havana, Cuba, was occupied by American troops in , Gorgas took charge of a yellow fever camp at Siboney, soon becoming chief sanitary officer of Havana. Acting on information that a certain mosquito carried yellow fever, Gorgas quickly destroyed that mosquito's breeding ground, ridding the city of yellow fever. In , work commenced on the Panama Canal. Gorgas went to the Canal Zone to take charge of sanitation, succeeding in Panama and Colon. Gorgas came to be generally regarded as the world's foremost sanitary expert, and a number of foreign governments and international commissions sought his aid.
His book Sanitation in Panama quickly became a classic in the public health field. In he was appointed surgeon general of the Army, serving in that capacity until his retirement four years later. Gorgas died on July 3, , and is buried in Arlington National Cemetery.
Disposing of the excavated material is one of the challenges of canal and lock construction. It may be used to construct embankments or be spread over the surrounding countryside where it is carefully landscaped for erosion control as well as appearance. Construction of the Divide Cut, a mi km canal on the Tennessee-Tombigbee Waterway, in the early s required the disposal of million cubic yards million cubic meters of dirt. During lock construction, excavated material can be used to fill cofferdam cells.
When the cofferdam is removed, the material may be used to fill in behind the riverbank side of the lock wall. Lock operation uses large amounts of water; for example, it takes 3. On some canals and rivers, water supplies are limited and conservation is important.
Rather than being released downstream as the lock is emptied, some of the water may be diverted to a side pond, where it can be stored and used to help fill the chamber for its next operation. Because of the significant need to recondition or replace locks as well as build new facilities, the U. Army Corps of Engineers sponsors and conducts research on water-way construction. Scale models of proposed designs can be tested at its Waterways Experiment Station. Through its Innovations for Navigation Projects INP Research Program, it supports the development of new ways to build, repair, and operate canals and locks.
Recent topics included improvements in underwater concrete and grout placement and development of low-density, high-strength concrete for building modular lock sections that can be installed without construction of a cofferdam. The digging of canals for irrigation probably dates to the beginnings of agriculture, with traces of canals found within ancient Chinese, Egyptian, and Babylonian civilizations. Written evidence shows that the Suez Canal, for instance, was excavated prior to B.
It was documented to be navigable for small vessels by B. One of the world's longest canals, the Grand Canal of China, was constructed primarily during the seventh and thirteenth centuries.
The 1,kilometer 1,mile canal connected the cities of Beijing and Hangzhou, and is often considered the most notable of the early canals. The regions that built canals during the pre-industrial era were those possessing fairly level landscapes, like Mesopotamia around Iraq and Iran , Egypt, and China, or where channels were branches of the sea, like in the Netherlands.
This pattern occurred because the practice of building locks had not yet been invented. Nevertheless, these waterways were not constructed on one continuous level. Evidence shows that the early Egyptian and Chinese canals were adapted to the differing land contours, often using an inclined plane for transferring boats to successive levels. Even today, China uses similar methods on its extensive canal system.
The introduction of locks throughout Europe—primarily for economic, political, and military gains—between the fifteenth and seventeenth centuries spurred rapid canal-building.
France was the first to build extensive systems. The canal, completed in , was an enormous undertaking with its length of kilometers miles , rise of meters feet above the sea, numerous locks and aqueducts , tunnel of more than meters feet , and capacity for floating gigantic barges. Gangs of laborers called "navvies" or "navigators" first constructed British canals to provide artificial waterways for more efficient transportation of Historically, canals were constructed to "extend the sea," thereby connecting the sea with cities, and cities with the countryside.
This scene of Hamburg, Germany in illustrates how canals influenced city life and culture. Canals served to open up countries to the Industrial Revolution, just as the Internet is opening up the world to the Information Revolution.
Waterways afforded a cheap means of transportation, one that could bring input materials to production centers and then take finished products away for mass marketing. Thus, canals played a role in aiding the movement of populations to production centers. Canal building in Ireland, Scotland, and England flourished in the late eighteenth and early nineteenth centuries.
The Grand Canal was begun in for trade and passenger transportation, and extended kilometers 83 miles between Dublin and Shannon Harbor. The Caledonian Canal was completed in as a kilometer mile waterway from Inverness to Fort William, to provide a safe route for naval ships during the Napoleonic wars. The Manchester Ship Canal, which was completed in , opened Manchester Port to oceangoing vessels, and contributed to the thriving industrial English economy.
Belgium, France, Holland, and Germany became the first countries in Europe to develop inland waterway systems by using canals A large cruise ship and another oceangoing vessel pass through the Miraflores Locks of the Panama Canal. This large navigation canal, connecting the Pacific and Atlantic Oceans, is often referred to as the "eighth wonder of the world. Today these countries possess an integrated waterway network such as the Midland Canal, a series of German canals that facilitates east—west transportation of raw materials and manufactured goods.
In , a small excavation was cut across a narrow piece of land in a bend of the Mohawk River near present-day Utica, New York. It is commonly believed that this canal was the first artificial waterway to be created in the United States, and today it symbolizes the beginning of the U. The first U. Two levels that were connected by a water-filled incline transported boats by dragging them with cables operated by waterpower.
The construction of the Erie Canal, started in , was largely responsible for opening the American Midwest to settlement. More than 7, kilometers 4, miles of water routes, mostly in the middle Atlantic and central states, were created from the seaboard to the inland lakes to help expand a fledging country. Large canals are primarily built for navigation. Navigation canals were developed after irrigation canals, and for a long time were level, shallow depressions, or had inclined planes in which vessels were hauled between levels.
For instance, one of the first rail lines to be established in the United States in , the Philadelphia and Columbia Railroad, was built to complement the Schuylkill and Union canals between Harrisburg and Philadelphia.
Another important rail line completed the same year was the Allegheny Portage Railroad, which was the first railroad constructed through the Allegheny Mountains part of the Appalachian Range , linking two canal cities; Johnstown east of Pittsburgh and Hollidaysburg west of Harrisburg.
Lawrence Railroad, completed in between La Prairie and St. Jean-sur-Richelieu, was also built with the same rationale; a portage between the St. Lawrence and Lake Champlain. By the late 19th century, most of the canals were abandoned as they lost their commercial utility.
Many had limited draft, high upkeep and were no longer able to compete effectively with railways. Those left today, such as the Erie Canal, the Rideau Canal, and the Champlain Canal, are used for recreational purposes and managed by state or federal governments as parks.
Portions of some canals have been restored, again for recreational purposes. The only commercial exceptions are the Welland Canal, upgraded several times, which is now part of the St.
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