Historical Context: Improving Lift Locks
F. Daniel Larkin, SUNY Oneonta
Lift locks are an integral part of the operation of the state’s modern canals. Given the terrain through which New York built most of its canals, lift locks are indispensable, since their purpose is to raise and lower vessels. When completed in 1825, the Erie Canal needed 83 locks (an average of one lock per five miles of canal) to overcome the rise of 565 feet between the Hudson River at Albany and Lake Erie. By comparison, the Black River Canal, built through the rugged Tug Hill Plateau, required 109 locks, an average of 15 locks per five miles of canal.
Construction crews built New York’s canal locks of wood, wood and stone, stone, and reinforced concrete. During the 19th century, cut stone was the preferred material for lock walls; in the 20th century, it was reinforced concrete. Because wood was plentiful, some 19th-century New York canals, such as the Chemung, had wooden locks. The use of wooden lock walls on the Chemung Canal helped make its 39 miles the least expensive to build of any of New York’s canals. But wooden locks deteriorated rapidly, and the Chemung’s were rebuilt twice during the canal’s 45 years of operation.
Lock walls varied in height, depending on the elevation to be overcome, along with the need to maintain a water depth of four feet. During the 18th and 19th centuries, canal locks had wooden gates. (Today, lock gates on the modern Erie Canal are made of steel and weigh as much as 300 tons.) Water entered or exited the lock chambers through paddle gates, which were small doors in the main gates. Lock tenders first opened the paddle gates. Then they pushed against heavy beams mounted on top to open or close the main gates. The meeting edges of the gates were angled, so that the gates closed facing inward toward the chamber. This allowed the pressure of water in the lock to keep the gates tightly closed. Even so, lock gates leaked profusely. Modern steel gates are operated by electricity, as are the valves that control the flow of water into or out of the lock chambers. Nonetheless, water still enters and exits the locks by force of gravity, just as it did centuries ago.
In addition to the lock gate hinges, canals often have bumpers on the lock walls to help prevent injury to the boats and to the lock walls themselves. In the 19th century, the bumpers consisted of long pieces of wood attached vertically along the lock walls. Occasionally these can still be seen on abandoned canal locks. Today, older stone and modern iron and steel snubbing posts help secure boats in the lock chambers.
The water chambers of the original Erie Canal locks measure 90 feet by 15 feet. The size of the lock chambers dictated the dimensions of the canal boats. Locks on the original Erie could accommodate boats of approximately 80 feet by 14 feet. The first Erie enlargement increased lock size to 110 feet by 18 feet. Boat builders reacted almost immediately by making larger craft. Newer, larger boats could not use other state canals, since the locks of the attached lateral canals usually were built to the same dimensions as those of the original Erie. Today, the Erie Canal’s concrete locks measure 300 feet long by 44.5 feet wide, with a lift elevation of between 6 feet and 40.5 feet.