Sketch of an engineering and survey crew at work investigation a site for the enlargement of the Erie Canal
Suggested Teaching Instructions
Building the “Grand Canal”
F. Daniel Larkin, SUNY Oneonta
On the morning of July 4, 1787, a group of dignitaries gathered on a plot of marshy ground south of the village of Rome, New York. There, they dug the symbolic first shovelful of earth that began construction of the Erie Canal.
The New York State Canal Commision, which oversaw the construction of the Erie Canal, drew up the first building contract a few days later. As usual, the work went to the lowest bidder. Contractor John Richardson and canal commissioners Myron Holley and Samuel Young signed the document on July 12, 1817. It stipulated that Richardson would “grub, clear, excavate, embank, and construct in a good substantial and workmanlike manner a part of the first section of the canal.” In keeping with the democratic reforms sweeping the country, the state government offered contracts for lengths of as little as one quarter mile of ditch to allow as many people as possible to benefit from the project. Richardson contracted to build 61 chains and 50 links of canal, amounting to slightly more than three-quarters of a mile.
Building New York’s “Grand Canal,” as the Erie Canal often was called, involved excavating a ditch between the Hudson River at Albany and Lake Erie at Buffalo. The canal ditch was 363 miles long, 40 feet wide at the surface, 26 feet wide at the bottom, and 4 feet deep.
Before the contractors could begin excavation, engineering parties had to stake out the line. A party consisted of a principal engineer, one or more assistant engineers, targetmen, and axemen. Axemen were the lowest-ranking members of the party. Their job was to cut the stakes used in marking the canal line and to remove brush, small trees, and other similar obstructions. Targetmen occupied the next level in survey parties. They held targets, which were rodlike instruments 10 feet long, used to help surveyors measure changes in elevation in order to maintain the necessary level. In 1817, targetmen were paid three dollars a week. Engineers occupied the highest rank. They were responsible for making the three-dimensional measurements needed to construct the canal ditch. Engineers received at least a dollar a day plus expenses.
Nearly all the excavation was done by men using picks and shovels and by draft animals (animals that pull heavy loads). Workers used black gunpowder to blast through rock, with the powder holes drilled by hand. Very few machines were available to supplement physical labor, but there was one machine to bring down trees and another to pull stumps. The first machine worked by attaching a line near the top of a tree, then winding the line on an endless screw turned by a wheel, pulling the tree down. The stump removal device had a huge axle - 30 feet long and 20 inches in diameter - supported by two wheels, both 16 feet in diameter. In the middle of the axle was mounted a third wheel, 14 feet in diameter. Workers placed the machine over the stump and then attached the stump to chains wound around the axle. Draft animals pulled a rope wound around the center wheel, 14 feet in diameter. Workers placed the machine over the stump and then attached the stump to chains wound around the axle. Draft animals pulled a rope wound around the center wheel and thus ripped the stump from the ground.
The Erie Canal contained locks, aqueducts, and waste-weirs (structures designed to eliminate excess water), as well as side walls in some places. Builders used cut stone to make almost all of these structures, parts of which were always submerged in water. To build these structures, engineers needed hydraulic cement, which would harden under water, to hold the stone in place. This posed a serious problem: There seemed to be no source of cement in the United States; apparently, it would have to be imported from Europe at considerable cost. Then limestone was discovered near Chittenango, New York. When burned, crushed, and mixed with sand, the limestone produced cement that hardened under water. Canvass White, a canal engineer and native New Yorker, is credited with inventing hydraulic cement in America.
By the end of the 19th century, the application of steam power to machinery altered canal construction methods. Steam shovels largely replaced pick-and-shovel excavation. Railroad locomotives and dump cars took over from teams and wagons, and steam drills bored holes for the placement of dynamite, the new high explosive. Poured concrete reinforced with steel rods replaced stone in canal structures. When New York built the Barge Canal System in the early 20th century, all these machines and techniques were used, reducing the need for manual labor.
F. Daniel Larkin, SUNY Oneonta
Engineers built many structures to aid in canal operation. Most numerous were lift locks, which transported boats from one level to another. But there were also many other specialized structures, including dry dock locks, weigh locks, guard locks, aqueducts, bridges, waste-weirs, basins, and reservoirs.
Of course, the ditch itself was a canal structure. Manual laborers dug out the required dimensions. Usually, they piled excavated material on either side of the ditch to become the towpath and berm banks. (A berm is a ledge or shoulder along the edge of a road or canal.) Towpaths, used by the teams of horses or mules that pulled the boats, were built on only one side of the canal. The opposite bank was the berm. Sometimes, particularly early in the spring, canal banks collapsed. When a break occurred, the water in that section rushed out of the canal and often carried boats with it.
Dry dock locks were designed so that boats could be repaired on the canal. A dry dock lock had walls enclosing three sides and a wooden gate at one end. Once a boat entered the lock, the gate was closed and the water pumped out. Repairs to the boat could then be completed. There is a dry dock lock on the Delaware and Hudson Canal, which was built to transport coal from northeastern Pennsylvania to the Hudson River at Kingston, New York. Although this canal has been closed for nearly a century, it has many intact structures. Dry docks also may be seen at Chittenango. The museum there is re-creating the 19th century boat repair facility and canal store that once stood on the site.
The weigh lock was another type of canal lock. Its purpose was to weigh boats to determine the amount of toll due on the cargo. When the boat entered the lock, officials measured the total weight of the boat and water in the lock. Then they deducted the weight of the water and that of the empty boat; the remainder represented the weight of the cargo. Charts showed the amount due on each item. A weigh lock building still stands in Syracuse; today it houses a canal museum.
Guard locks were built to let canal boats cross through streams and rivers. In these situations, a dam was constructed a short distance downstream from the crossing. The dam raised the water level to the depth required for the boat to cross the stream and helped still the motion of the water. Boats passed from the canal, through the guard lock, across the stream, and through the opposite lock back into the canal. The guard locks also prevented stream water from entering the canal. Crossing streams and rivers by using guard locks was known as slack water navigation.
Workers built aqueducts to allow canals to cross over rivers and streams. Simply put, canal aqueducts were bridges for boats. Stone arches carried the weight of the wooden water chamber, or trough, through which boats passed. Eventually, aqueducts replaced some slack water navigation. John Roebling, a pioneer in suspension bridge construction, designed four novel “wire rope,” or cable suspension, aqueducts for use on the Delaware and Hudson Canal. One of the Roebling aqueducts remains in use as an automobile bridge across the Delaware River.
There were also many bridges along canals. In cities and villages, large and elaborate bridges were made of wood, iron, and, later on, steel. Simple wooden farm bridges were most numerous on 19th-century canals. They were inexpensively built to connect farm fields separated by the canals, providing as little clearance for boats as possible. When a boat passed under a low bridge, passengers on the upper deck had to duck or they would be knocked off.
Waste-weirs were stone structures designed to rid canals of excess water. Most of the early canals in New York maintained a constant water depth of four feet. Less than four feet of water would cause boats to scrape the bottom of the ditch; more than four feet could damage canal banks. The spillway of the waste-weir was built to the height of the required water depth so that unneeded water could “waste” over the top. Modern waste-weirs are constructed of reinforced concrete.
Occasionally reservoirs, or artificial bodies of water, were constructed to supply canals with water. This was particularly necessary for interbasin canals, which connect two watersheds. At the highest points of the dividing line between watersheds, water is often scarce. Reservoirs, fed by natural springs and runoff, were sources of water for interbasin canals.
The successful operation of the Erie Canal depended on the construction and maintenance of this complex system of specialized structures.