The depicted dry dock – a drainable basin formed by three masonry walls 98.5 feet in length and 14.5 feet in width – was constructed for the repair and maintenance of canal boats along the eastern side of Lock 35.
A boat would enter the dry dock from the upstream (northern) end of lock 35 where the canal had been widened to a width of 75 feet. Once inside, wooden stop planks were dropped to seal off the basin from the canal. The water within was drained through a wicket gate in the downstream wall. The boat would come to rest on top of six concrete yokes – these may initially have been wooden – equally spaced along the basin and visible in the photograph. Wooden shims were used to stabilize the boat on the yokes so that workmen could access the dry exterior of the boat as they made repairs.