Historical geography — locks

File with missing and current locks as well as the type of lock. Locks, or sideways, are artificial water discharge points and points for water supply. Its construction is linked to the closure of areas of the bosom or seawater through dikes. The Frisian bosom was at first probably one system of interconnected waters, but from the late Middle Ages began to separate by means of locks and the bosom was divided into smaller bosoms. Different types of locks are distinguished: diver lock or pump; leave or lock, side or drainage lock.