What are locks anyway? Do you need a key?
While you would need a key to open a standard lock on your front door or your car, you won’t need one to open an Erie Canal lock. This discussion is about a different type of lock —a water lock (lock).
A lock is a structure found on waterways used for raising or lowering vessels from one water level to another. Locks consist of a rectangular chamber with swinging gates at each end. The gates meet in the center and open or close allowing vessels to enter or leave the lock chamber.
Why is it necessary to raise or lower vessels on a waterway? It’s necessary to raise or lower vessels on rivers or canals for several reasons, including changing terrain levels, rapids, shoaling, waterfalls and low water.
The Erie Canal is a good example of terrain change. The terrain change across New York State, from the Hudson River on the east to Buffalo and Lake Erie on the west, is 565 feet. A vessel leaving Albany, NY must travel through a series of locks that will raise her 565 feet before arriving in Buffalo. Picture locks as a set of “stair steps” across the state— “liquid elevators” if you will.
On the Erie Canal the waterways between the locks (sometimes as little as a ¼ mile and other times 50 or more miles) are call “pools”. Because it’s difficult and unsafe for vessels to attempt going “uphill” or “downhill”, the “pools” must be level to provide safe navigation. The method used to level the “pools” is to build a dam either downstream of a lock (or sometimes at the lock itself). The dam raises the water level of the “pool”. This creates a level and deeper channel that makes the “pool” safely navigable.
The history of locks is a subject in it self and would take a book if explored completely. Here’s a quick overview of how locks came into being.
Locks date back to the Chinese, over 2000 years ago (50 B.C.). The first locks were called “flash locks” and consisted of nothing more than a dam with a gate in the center which could be raised or lowered. Picture a vessel heading downstream ( “downhill”) in a river with the current at her back. As the vessel approaches the dam the flash lock operator(s) lifted the gate and the vessel would “flash “ through and depending on the strength of the current——not always safely. I picture it as an early version of a thrill ride at one of today’s amusement parks. Now, picture a vessel heading upstream (“uphill”) in a river against the current. As the vessel approaches the dam, the gate is opened and the vessel must be pulled through manually against the current. I wonder how many people that took to accomplish and if any of them were lost downstream to the current? I wouldn’t have wanted to be one of the people pulling the vessel through the gate. Obviously this was a mighty slow and hard process. However, the crews on vessels going upstream were much safer than the crews going downstream.
Luckily, around 1000 A.D., the Chinese came up with a much better idea and designed what became known as the “pound lock”. This style lock consisted of two “flash locks” separated by a few hundred feet. The space between the two “flash locks” created the lock chamber. Because the chamber “impounded “(trapped) water, this type of lock became known as a “pound lock” and is basically the same as the locks of today. The swinging gates at each end met in the center and were straight across, so there was still the problem of water leaking out of the chamber through these gates. It took Leonardo DaVinci around 1480 to invent a much improved version of the pound lock. He simply had the swinging gates meet in a shape of a shallow V with the point of the V facing upstream. Once the gates were closed the water pressure would push the gates together at the V and create a watertight seal. Believe it or not, most all locks to this day are built that way and DaVinci is generally credited as the inventor of today’s locks. These gates are called “miter-v” gates.
How do today’s locks operate?
Most of the locks currently in use throughout the world do not have pumps to move the water in and out of the lock chamber. They rely on the principal of gravity———–water will seek its own level.
Erie Canal locks consist of two sets of Miter-V gates to form the chamber and contain the water , underground tunnels for the water to flow in or out and tunnel valves (they resemble guillotines) to open or shut the water flow through the tunnels. The lock chamber and floor is made of concrete. Lock 18 at Jacksonburg NY uses about 2 million gallons of water every time a vessel(s) “locks thru”.
So, where does the water come from and where does it go?
In the early days of the Erie Canal (1825-1918) the canal was a man made ditch 40 feet wide and only 4 feet deep. Rivers, streams and tributaries acted as “feeders” which were allowed to run into the ditch (canal). There were many times when there was either too much or not enough water in the canal. The problem of having too much water was typically solved by allowing spillways ( called “weir’s”) to let excess water run out of the canal and back into the “feeders”. The problem of too little water was usually solved by mother nature—rain and/or water run off into the feeders.
When the current Erie Canal was constructed (1905-1918) it was no longer a ditch and was much larger than the original canal. The new canal utilized natural rivers and lakes as part of the navigable waterway and it required a reliable, constant source of water. In our eastern section of the canal (Hudson River to Rome NY) two main reservoirs were created around 1912 to store and supply the necessary water for the canal. They also control the amount of water allowed to enter the canal. These are the Hinckley Reservoir north of Utica and Delta Lake (the headwaters of the Mohawk River) north of Rome. From there our area of the canal is fed through the West Canada Creek. The new Erie Canal opened in 1918 and up to now has never once experienced less water then what’s required for it to remain operational. The water eventually flows through the Mohawk River, then the Hudson River and finally out into the Atlantic Ocean. So we could say that the water flows continuously from the reservoir’s to the ocean.