The tide pond gates at the Slade Mill in Revere are what we think of as typical. The incoming tide pushed the gates inward into the pond. When the tide receded, the gates would close automatically due to the outward flow of the water. Illustrations from The Spice Mill on the Marsh by Thomas P. Smith. Norfolk Downs, MA, 1925.
The types of gates are shown from the most common to the least: side-swinging, flap gate and lift-gate.
