File:Lock 68 on C and O Canal from NPS.jpg

English: Lock 68. NPS site says: Lock 68 is the 10th Composite Lock. These locks differ from the other locks on the canal. Between the upper end of the lower gate pockets to the lower end of the upper gate pockets the stone walls were moved 9 ¼’ on each side, resulting in a clear dimension between lock walls of 16’-16 ½” rather that the 15’ previously adhered to. The normal clear dimension was resumed both up and down from these points. The walls were of rough-cut and rough-coursed limestone, principally dry-laid where the walls were widened and mortared in the other areas. The wider area was filled in with 5 ¼” square timbers. This wooden section of the lock was “water-proofed” at first by being “kyanized” and later with creosote. The wood timbers required frequent replacing, and around 1900 many repairs were made by stripping out the wood and pouring a cement liner.

Lock 68 is nearly 2 miles below Lock 69, and 2 ½ miles above Lock 67. It has a lift of 8¼ feet. Although the concrete liner is undated, it was probably added in the early 1900's when most of the wood liners of the composite locks were replaced. Concrete covers all the lock walls, from the lower end of the upper lock gate-pockets to the start of the lower extension walls. All wood coping was replaced with concrete. On the towpath side spaced bolts that protrude 4" above the concrete, indicate an added continuous wood member. This wood extension may have been added because the concrete edge, over which the tow ropes ran, made the life of the tow ropes quite short. Lock 68 was extended at its lower end by rock-filled wood cribbage in the 1870's to double its length. Rock-filled wood cribbage was also used at the berm side upper end of the lock to divide the flow of water into the lock and the by-pass flume. The lock is at it upper end dammed by a concrete wall as a result of a post-World War II

endeavor to create fishing areas in the canal bed in this area. There is a wooden barrier across the lower end of the lower gate pockets, purpose unknown. There are 12 foot high stone bridge abutments located at the lower end of the lock, which carry an iron bridge over the canal (LCS#45620) and a modern pedestrian bridge at the lower end.