How a lock works.

How do locks work? Well, there are many different kinds of locks but, before I start, I thought it would be nice talk about their history and why they are the way they are.

Locks have been around for a long time in one form or another. Today, we might not even recognise their ancestors from China called flash locks, used as early as 50 B.C.E. Flash locks worked by having a gate at the end of a river which could be opened to release a “flash” of water carrying a boat downstream across shallow water. Although it was dangerous to go down stream, going upstream was not as hard, but you had to keep the “flash” moving for a extended period of time. Going upstream was done by winching or dragging the vessel through the gate. 

Later, a second gate was added to the flash lock thus giving birth to the pound lock. Pound refers to its dual gates “impounding” or capturing  the water. The first known example of a pound gate was in 984 C.E. in China, which consisted of 2 flash locks about 76 meters apart. By raising or lowering one of the gates on either side water could be captured or released. This new method was a lot easier to control, and did not have the risks of the flash gate.

During the fifteenth century Italian artist and scientist Leonardo Da Vinci made a improvement on the pond lock. The gates now formed a v-shape pointing upstream and turned on hinges like doors. The new self sealing gates were called mitre gates.

So… how do locks work? Well, if you were going downstream on a modern day lock one of the 2 v-shaped gates would open to let your boat through then close behind you. The water under your boat would slowly be drained out, taking advantage of gravity, and dispersed through the lower canal. Then your boat would slowly descend until it was level with the lower canal, the other door would then open letting you out. If you were going upstream the gate would open to let you through then close behind you, water would be pumped into the rectangle in between the 2 gates until it was level with the water in the higher canal. You would then be let out.

Some gates like the one we went to a couple of days ago are moved by humans. The gate we went to had giant levers to open and close the gates and cranks to open a small gate where water from the upper level could run into the lock.