Supplement to Image #15

Image #15 shows a reflection of the abutment on the Maryland side of the New Armory Dam, constructed between 1859-61 to supply water power to the national armory at Harpers Ferry on the West Virginia shore (originally the State of Virginia). Adjacent to the Chesapeake & Ohio Canal and constructed from grey limestone with rough facing, the structure was intended to improve on – and ultimately replace – Dam #3 (visible in the map below, also known as the “Government Dam”). The latter, built in 1799 over the Potomac river, supplied both the armory and the Chesapeake & Ohio Canal with water.

The national armory at Harpers Ferry was first established in 1802. Between 1844 and 1854, extensive expansion of the buildings and machinery had necessitated the need for more water power. The armory canal was enlarged and seven new water turbines were installed.

With the destruction of the armory during the Civil War, the dam was never completed.

Left: "Map shewing [sic] the routes surveyed for the Balt. & Ohio Rail Road." C & 0 Canal Files, National Capital Parks, National Park Service, Record Group 79. Courtesy of the National Archives, College Park, MD

Right: Abutment of the New Armory Dam. circa 1970. Photographer, Thomas Hahn. From the Thomas Hahn Chesapeake and Ohio Canal collection, circa 1939-1993, at George Washington University.


Supplement to Image #14

Image #14 looks downstream along the Chesapeake & Ohio Canal to Lock 27, also known as Spinks Ferry Lock and, in nineteenth-century records, as Campbell’s Lock. Completed in 1832, Lock 27 is located three-quarters of a mile downstream from the Monocacy Aqueduct. The coping (the stones capping the upper edges of the lock) is comprised of high quality red sandstone from the Seneca quarry. The lock itself is built of red sandstone sourced from a quarry 2.5 miles downstream from Point of Rocks, MD.

Thomas Walter, the lock’s first keeper, did much to limit the damage done during the Civil War. In September 1862, he persuaded the Confederate army, intent on halting transit on the waterway, to refrain from using explosives to destroy the Monocacy Aqueduct and Lock 27 and, instead, to drain the canal by cutting the banks (as can be seen in the rubble on either side of Image #14). Walter’s actions ensured the survival of the masonry structures and of the canal as a whole. Following the war, he was discharged from the canal company for alleged collaboration with the Confederate army; however, a successful petition by witnesses and neighbors led to his reinstatement.  

Lock 27 was the uppermost (and final) lock to be constructed using a design in which water entered through culverts positioned within its walls. In subsequent locks (built post-1830), bypass flumes replaced culverts altogether. Later still (circa 1870), the upper end of the lock was doubled in length in order to allow two boats to be raised or lowered at a time. 

Lock 27, upper end (left) and lower end (right). January 1974. Photographer, Thomas Hahn. From the Thomas Hahn Chesapeake and Ohio Canal collection, circa 1939-1993, at George Washington University.

Special thanks to Yuriko for helping to photograph Image #14.


Supplement to Image #13

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 Image #13. 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. 

C & O Canal Plan of Two Locks Harpers Ferry (detail). C & 0 Canal Files, National Capital Parks, National Park Service, Record Group 79. Courtesy of the National Archives, College Park, MD

Special thanks to Yuriko for the education in lepidoptera and assistance in photographing Image #13.


Supplement to Image #12

In 1956, President Eisenhower signed the Federal Aid Highway Act. Within two years, planning began to establish Interstate 95 (I-95) as the main highway on the East Coast, running from the Canadian border in Maine to downtown Miami, FL. Work on the I-95 section between Baltimore and Washington DC commenced in 1968. This length of highway opened in 1971.

The current I-95 Patapsco bridge was built in 1982. The concrete structure of 7132 feet falls in one of the most heavily traveled routes in Maryland, transporting an average of 115,500 vehicles daily (as of 2001) over the Patapsco River and the CSX Railroad (previously the Baltimore & Ohio Railroad Main Line). 

Message to the Congress of the United States regarding highways, February 22, 1955. Office of the Press Secretary to the President, Box 4, Press Releases Feb. 8-March 14, 1955, Courtesy of the Dwight D.  Eisenhower Presidential Library, Abilene, KS.


Supplement to Image #11

An embankment of stone to be raised from the bottom of the (Potomac) river in the line of wall, having a slope of 1 1/2 to one both outward and inward. This embankment should be about 6 ft. at surface. As it approaches the surface of the water it should be laid with as much care and compactness as may be practicable – the longest stone to be laid in manner of headers.
— Instructions on building an embankment from Herman Boye, resident engineer of the 5th Residency on the 1st Division, to Almon H. Millerd, contractor

The Chesapeake & Ohio Canal was designed to run along the eastern side of the Potomac River, creating a navigable route between Cumberland, MD and Washington, DC. By June 1829, the ideal width and depth of the canal had been defined as follows: breadth on the surface of the water of 60 feet; depth of 6 feet; and breadth at bottom of the water of 42 feet. The area of the resulting cross section equaled 301 feet. 

In a number of areas north of the Seneca Quarry, the construction of the canal ran into problems due to the cliffs of heavy rock (primarily sandstone) projecting into the Potomac River. Contractors had to blast the canal through the rock and construct embankments to separate the two waterways.

Image #11 shows an area of the Chesapeake & Ohio Canal located near Lock 26. Built in 1830, this section of the canal was constructed by a team led by Almon H. Millerd, contractor, and supervised by Herman Boye, engineer. The photograph was taken standing on the embankment – a structure built to prevent the canal from caving in and to protect it from high levels of water in the adjacent river – and looking across the canal at the blasted rock face.


Supplement to Image #10

Rock Run is a tributary stream that flows into the Potomac River. During the American Civil War, gold was found in the the Rock Run area. Between 1867 and 1940, at least five mines were established along Rock Run. In the largest, which operated between 1910 and 1920, gold nuggets of up to four ounces in weight were reportedly recovered.

Built in 1963, the Rock Run culvert is a concrete twin tunnel culvert that passes underneath the Clara Barton Parkway and the Chesapeake & Ohio Canal, near Lock 12. In the 1940s and '50s, the direction of the stream was changed to run through the edge of the Carderock Division of the Naval Surface Warfare Center. Originally, Rock Run passed beneath a different culvert near Lock 11 on the Chesapeake & Ohio Canal, over half a mile to the west.

Left: Modern culvert at milepost 9.54. Photographer, Thomas Hahn. From the Thomas Hahn Chesapeake and Ohio Canal collection, circa 1939-1993, at George Washington University.

Right: Site Plan of Rock Run Outfall (detail). C & 0 Canal Files, National Capital Parks, National Park Service, Record Group 79. Courtesy of the National Archives, College Park, MD.


Supplement to Image #9

Image #9 shows the reflection of White’s Ferry Bridge in a pool of water within the culvert running under White’s Ferry Road.

From the 1860s, White’s Ferry Bridge in its various iterations, supported traffic over the Chesapeake & Ohio Canal to the nearby ferry crossing. The latter was originally known as Conrad’s Ferry and was renamed White’s Ferry in the wake of the Civil War. It remains the only functioning ferry crossing the Potomac River.

The initial bridge was erected in 1865. The structure’s red Seneca sandstone abutments (visible in the photograph below) are original to this structure. However, its wooden truss was subsequently replaced by an iron framework that opened to traffic in June 1876. The second bridge was further adapted in circa 1920 with modifications to the truss system (Warren pony truss design system). The bridge has been abandoned, leaving only its framework standing today.

Left: Historic American Engineering Record. Jet T. Lowe, photographer, Chesapeake and Ohio Canal: Bridge at White's Ferry, North Elevation, Haer MD-69-2, April 1989. Courtesy of theLibrary of Congress, Prints and Photographs Division, Washington, D.C.

Center & Right: Blueprint and Site Plan of White's Ferry Bridge. C & 0 Canal Files, National Capital Parks, National Park Service, Record Group 79. Courtesy of the National Archives, College Park, MD.


Supplement to Image #8

Between circa 1781 and 1901, the Seneca Quarry produced distinctive red sandstone used extensively in the Washington, DC area, notably in the construction of the Chesapeake & Ohio Canal and the original Smithsonian Institution building ("The Castle"). Seneca red sandstone (also called red stone) was valued for the ease with which it could be cut as well as for its durability and bright color. Initially lilac grey when quarried, the stone turned red as the iron in the stone oxidized. 

Located on the edge of the Seneca Quarry and built from red sandstone, the Stone Cutting & Dressing Building was where stone was shaped and polished. The structure’s southeast exterior wall is visible in the background of Image #8. All that remains of the machinery is the water channel in the foreground, the former location of the water-wheel/turbine that powered the cutting and dressing machines within the building. As seen on the map below, water purchased from the Chesapeake & Ohio Canal Company ran from the Turning Basin though a water wheel/turbine system to Seneca Creek. 

The building and quarry were abandoned in 1901 when veins of good stone ran out.

Map and blueprint of the Seneca Quarry Cutting Building, Seneca, MD from the Division of Mechanical and Civil Engineering, Museum of History and Technology under the direction of the National Park Service, 1972.

Special thanks to Mark for assistance in both photographing and researching Image #8.


Supplement to Image #7

Lock 21 is called Swain’s Lock after the Swain family. Members of this family worked on the Chesapeake & Ohio canal since its construction and resided in Lockhouse 21 from 1924 through the early 2000s.

Construction on the 91-foot Lock 21 was begun in July 1829 and completed in October 1830 by the firm of Holdsworth and Isherwood for a total cost of $8,327.76. The Lock was built from red sandstone from the Seneca Quarry, Montgomery County, MD. A few of the stones in the lock wall can be identified with an individual stone cutter who used the mason’s mark, E*.

Built using an 1828 design, the Lock was intended to be filled with water by culverts in the walls. Because these culverts frequently became clogged with debris, lock gates with inset wickets—easier to maintain and replace—were added in the late nineteenth century. The water level in the Lock varied by approximately 8 feet.

Left: Blueprint of Lock 21 (detail). C & 0 Canal Files, National Capital Parks, National Park Service, Record Group 79. Courtesy of the National Archives, College Park, MD.

Right: Photograph of Swain's Lock (Lock 21) and lockhouse , circa 1938. From Mackintosh, Barry. C & O: The Making of a Park. Washington: History Division, National Park Service, 1991.


Supplement to Image #6

February 16 (1959). A new landmark only 155 feet shorter than the Washington Monument, now pierces the skyline. It is the Tower of Potomac Electric Power Company’s new $55 million plant under construction at Dickerson, MD., designed to channel fumes away from residents.
— Records of the Columbia Historical Society, Washington. Vol 57/59 (1957-1959): 236

On September 24, 1959, Maryland Governor J. Millard Tawes inaugurated the Dickerson Generating Plant, a structure built for a total of $62 million by the Potomac Electric Power Company (Pepco). The initial height measured approximately 400 ft. Subsequently additional towers were added, the tallest of which reaches 700 ft.

Situated on the banks of the Potomac (straddling the Chesapeake & Ohio Canal), the plant uses the river’s waters to cool its coal-fired generators which produce a net capacity of 849 megawatts. The cooling water discharge returns to the Potomac River after flowing through a 900-by-30-foot canal. In 1991, this canal was transformed into a warm-water canoeing and kayaking whitewater course for Olympic training.

In December 2000, Pepco sold the plant to Southern Company of Mirant. Today, the plant is owned and operated by NRG Energy. It is still operational, but plans have been announced to close it permanently in 2017.

Left: Mirant coal fired electrical generating facility in Dickerson, MD, Eric Vance, Chief Photographer, Environmental Protection Agency, 1970. Courtesy of the National Archives, College Park, MD.

Right: Aerial photograph, Southern Company of Mirant.