McNown begins by explaining the development of canals in Europe in the 16th Century. The expansion of the canal system in Europe began by improving the navigability of rivers by removing obstacles or digging canals around rapids or other barriers. As engineers learned the advantages of canals for transportation compared to roadways, the expansion of the canal system continued. At the beginning of the 17th Century, England had 650 miles of navigable waterways, but by 1760, England had about 1200 miles of navigable waterways. Over the next few decades, this number doubles to accommodate the increased volume of barges.
Canals were preferred for the transportation of goods for several reasons. During the time period when canals were being developed, a horse could carry 250 pounds, pull 1200 pounds on a wagon on a rough road, and two tons on a wagon on a paved road. However, a horse pulling a barge on a canal could pull 50 tons with the same effort needed to pull a wagon. This increased the amount of goods that could be transported over long distances. As engineers learned more about the construction of canals, they determined that their cross section should be trapezoidal with the bottom being 20 to 25 feet wide and 30 to 40 feet wide at water level. This meant the water was approximately 3 to 4 feet deep. As a result, the water in canals was much calmer than rivers and other natural waterways.
When engineers planned where to build canals, they chose to follow elevation contours. However, there were some circumstances that required the canals to change elevation. This was done using locks, which is a simple hydraulic elevator. A barge would enter a lock on one side, and the water in the lock would then be pumped in or out to make it the same level as the water on the other side of the lock. This allowed barges to traverse elevation changes with ease.
In the United States, the construction of canals began much later than Europe. The first major canal project was the Erie Canal. This canal was proposed to go from Albany to Lake Erie and only had an elevation change of 568 feet, thus reducing the number of locks needed compared to other routes that had been proposed to go from Lake Erie or Lake Ontario to the Hudson River. After years of negotiating where the canal should be built and how it would be paid for, construction began in 1816. During the construction of the canal, several new technologies were invented to make construction easier, such as a horse-drawn scraper, a dumping wheelbarrow, a plow with a blade for cutting tree roots, and a new kind of stump-puller. The canal was finished in October 1825, and the total cost was $8 million. In the next few decades several other major canals were opened, such as the Chesapeake and Ohio Canal. While canals were being built, railroads were also expanded to meet the growing transportation needs in the U.S.
This link explains the development of American Canal systems as well as the various technologies used in canals. The financing of the canal projects are also explained in detail as well as what it was like to be a passenger on a canal boat.
This link is to a video the explains how a canal lock works.
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