The vast majority of the gates on the C&O Canal's locks are swing-arm style. Long horizontal wooden swing arms are manually pushed to open the pair of doors that comprise the gate.

In the latter stages of canal construction (probably the 1840's) the engineers experimented with a "new-fangled" gate design from Europe called a drop gate. These gates were used on a very few locks, and were for the upper gate only. The drop gate is basically a door hinged along the bottom that rotates to the bottom of the canal. The big advantage of the drop gate was that it could be managed by one person, using a large spoked wheel and levers, and in much less time. The effect was a substantial savings in lock-through times.

I spent an inordinate amount of time crafting these three images that hopefully depict the ingenuity and old industrial beauty of Lock 10's  drop gate.