GEORGE WASHINGTON MEMORIAL PARKWAY Patowmack Canal and Locks (Great Falls Section) Historic Structures Report — Architectural Data Section

"THE LOCKS AT THE GREAT FALLS OF THE POTOMAC"
excerpt from "A Journal of Accounts &c, Thomas Harbaugh, with, the Potomac Company and Others, from 1803 to 1833"

The locks at the Great Falls of Potomac are six in number, situated 14 miles above George-Town, a great part of them are blown out of the solid rock, a work of much labor and expense. A further description of the size &c of the locks are From Gate No. 1, of Lock No. 1, at the Bason . . . to Gate No. 2 is 390 feet in length 25 feet wide and 6 feet deep, from Gate No. 2 to Gate No. 3 is 112 feet in length 15 feet wide and 14 feet deep, called Lock No. 2. Thence from Gate No. 3 to Gate No. 4 is a small Bason 400 in length 30 feet wide and 5 feet deep, thence from Gate No. 4 to Gate No. 5 is Lock No. 3 is 97 feet long, 12 feet wide and 19 feet deep, walls made of red face stone cut. Thence from Gate No. 5 to a large apron is 97 feet in length 20 feet wide and 6 feet deep, thence from the apron to Gate No. 6 is Lock No. 4 . . . . 100 feet in length 12 feet wide and 16 feet deep, one side and the bottom is solid rock, thence from Gate No. 6 to Gate No. 7 is Lock No. 5 . . . 95 feet long 12 feet wide and cut down in the rock about 25 feet in depth — making both sides and bottom all solid rock, thence from Gate No. 7 to Gate No. 8 — is Lock No. 6 — is 84 feet by 12 feet wide and 24 feet deep with the sides and all the bottom solid rock — a portion of this rock has been cut down through the rock 43 feet in depth. The river rises into this lock in high water 53 feet in height — the whole length of upper to lower gates is 1,375 feet.

The Lock Gates "Timber" Irons — Great Falls

The battle gate rods are 1-1/4 inches in diameter rounded. The iron Pivots are 14 inches long by 2 inches square. The iron Bands are 1/2 inch thick and 1-1/2 inches wide. The caste iron straps 7 inches square by 2-3/4 thick—site in sills. The caste iron Battle gates are 19-3/4 inches wide and 23-1/2 inches high. The middle of the gate is made round and is 4 inches in Diameter, a square hole in the center of the round part for the Battle rod to pass through above and below — for all other irons of which they are very many of Different sizes and forms, see Big Book of Drawings of Locks &c &c and for the Manner of Doing the work and the Quantity of work that can be Done to the gates — sills — and other work, see the papers of notes put up in Book case from old Mem Book of 1802 — of which there is too much to insert in this Book, also the Different ways to hand the gates with iron or wood. The above sill of Gate Timber was of White Oak &c take one gallon of fish oil and 6 — of rosin and Boil well together and cover the Tennons — well before joined up.