File:Lock 59 C and O from NPS.jpg

English: Lock 59, second composite lock on Chesapeake and Ohio Canal. NPS site says: Lock 59 is the second of the 13 composite locks. 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, but at Lock 59 cement was not used. The wooden coping and most of the wood lining at Lock 59 is gone, but a few remnants remain, especially on the berm side wall.

In the mid-1870s, Lock 59 was extended at its lower end by rock-filled wood cribbage, in order to double its length. The wooden portion of the extension is largely gone, but the lines of rock remain.