Architecture and Technology of the Potomac Power Plant Potomac Hydroelectric Power Plant, On West Virginia Shore of Potomac River, Harpers Ferry West Virginia

The building that housed the Potomac Power Plant is a small, unpretentious brick industrial building dating for the most part to 1925, and measuring roughly 74 feet by 42 feet. To the casual observer, the old power plant looks like a hundred other nondescript industrial structures. In fact, the building is an icon of Harpers Ferry industry, and like a crazy-quilt, is composed of fragments of significant meaning.

The site of the power plant is historic, having been occupied by first the Harpers Ferry Armory's Tilt-Hammer Shop, built in 1834, and later by the Armory's new Rolling Mill, constructed in 1853. Although there is some evidence that Thomas Savery constructed new foundations for his pulp mill, he built the mill on the site previously occupied by both the Tilt-Hammer Shop and the Rolling Mill, and may have reused parts of the foundations for these structures for his new mill. The waste weir to the west of the power plant building may also contain historic elements. A map from the mid-1830s shows both the old Tilt-Hammer Shop and a waste weir, in the approximate location of the current waste weir.

Savery also presumably reused bricks from the ruined Armory buildings in erecting his new pulp mill. He had earlier reused bricks from the old rifle factory on Hall's Island to build the foundation for his pulp mill on the Shenandoah River, and his son William was quoted in a local newspaper in 1888, referring to the building of the Potomac Pulp Mill, that, "We...will tear down all the rest of the old works and use the brick in our new mills."

Building materials, in fact, were often reused in Harpers Ferry. Bricks from the ruins of the old rifle factory on Hall's Island were salvaged for the Methodist Protestant Church on Camp Hill and both the McGraw store and residence on Shenandoah Street, and Storer College's Lincoln Hall, a dormitory which was rebuilt after a fire in 1909, reused bricks from an old flour mill on Virginius Island.

After the 1925 fire destroyed part of the Potomac Pulp Mill, the Harpers Ferry Paper Company again reused bricks from another structure to rebuild the mill. The fire gutted most of the interior of the pulp mill, and collapsed the north wall. Two months after the fire, the remains of the west wall were demolished when high winds swept down the Potomac. Among the property owned by the company in Harpers Ferry was Virginius Island, which at one time had supported numerous industrial structures. The Child & McCreight Flour Mill had been built on Virginius Island in 1848, originally as a cotton factory. In 1925, after the fire, laborers for the paper company were paid for 'Hearing down part of the walls of the old Flour Mill and in cleaning the bricks used to construct a new wall on north and west side of Power House."

The Potomac Power Plant building, therefore, may be built on parts of the foundations of the 1834 Tilt-Hammer Shop and 1853 Rolling Mill, and contain foundation stones and wall bricks from any number of former Armory structures, as well as bricks from an 1848 cotton factory and flour mill on Virginius Island. Considering that the site was also the last of the water-powered operations of Harpers Ferry, the Potomac Power Plant is significant not only as an interesting hydroelectric facility, but also as a patchwork "true piece of the cross," containing structural elements both symbolic and real of Harpers Ferry's gloried industrial past.

The industry of Harpers Ferry owed its existence to water power, from the energy inherent in the flowing of the Potomac and Shenandoah Rivers. Throughout the nineteenth century, both private and government industry in Harpers Ferry established dams, power canals, raceways, and waterwheel and turbine installations to power a vast assortment of machinery. When Thomas Savery purchased the old Armory works on the Potomac, he inherited a stone filled crib dam, first constructed in 1799 and replaced in 1828, running across the river for 1,575 feet, and a long power canal that brought water to his mill site, and dropped it 25 feet on its path back into the Potomac River. The power canal varied in width from 50 to 100 feet, with a depth of from 15-20 feet. A sluice gate and overflow weir was located at the end of the power canal, near the mill site, to drain the canal and help control the water level.

The 25-foot fall (or head) of water at the mill site produced the energy to run machinery, and Savery constructed his new pulp mill with seven flumes to capture this latent energy. The exact number, type, and configuration of the various water turbines employed in the Potomac Pulp Mill is unclear, since the surviving records of the Harpers Ferry Paper Company and other sources often provide conflicting evidence. The Harpers Ferry Paper Company reported to the Commissioner of the Internal Revenue in 1925 that the company had equipped the mill on the Potomac with 10 water turbines, eight of which were paired together in four horizontal units (meaning six of the mill's flumes were presumably occupied by single or paired turbines). Six of the wheels were 33" "New American" horizontal turbines, manufactured by the Dayton Globe Company of Dayton, Ohio; two were 24" "New American" vertical models; and two were 33" horizontal turbines manufactured by the S. Morgan Smith Company of York, Pennsylvania. The memory of the author of the report to the Internal Revenue may not have been accurate, as the Dayton Globe Company included in an 1892 catalog a letter from Thomas Savery in which he praised the turbines he had purchased from the company. In this letter, Savery mentioned that the Potomac mill had eight Dayton Globe 36" turbines in four paired units, driving eight wood grinders. By 1908, the turbine complement consisted of eight 36" turbines (manufacturers and types not listed), two 27 and 1/2" turbines, and one 51" turbine. The 51" turbine was a vertical turbine manufactured by the Dayton Globe Company and purchased by the Harpers Ferry Paper Company in c. 1905 to specifically power a generator for its electric plant. A 57" vertical turbine manufactured by the S. Morgan Smith Company was added in 1923 to power another generator for the electric plant. The only water turbine still extant in the Potomac Power Plant, however, is the c. 1905 Dayton Globe turbine.

There is even less information available about the early generators the HFEL&P Co. used in its electric plant. One or more dynamos (generators) were in use as early as 1900, but nothing is known about what type these were or who manufactured them. A Sanborn fire insurance map of 1907 lists two dynamos for the mill. A local newspaper reported in 1909 that the company had ordered a $4,000 generator from Westinghouse, and in 1913, William Savery mentioned in a letter that the HFEL&P Co. had three dynamos. There were only two by 1917, however, when the company purchased a new General Electric vertical generator with a capacity of 240 kilowatts to replace a smaller generator supplying electricity to Brunswick, and to complement a generator dedicated to Harpers Ferry. In the winter of 1920-21, the HFEL&P Co. placed a small Westinghouse generator with a capacity of 200 kilowatts in the Shenandoah Pulp Mill as a backup to the equipment in the Potomac mill.

Because of increased electrical load, the HFEL&P Co. purchased another new General Electric generator in 1923, a new GE switchboard, new transformers, and a new water turbine from S. Morgan Smith. This is the generator which company officials claimed malfunctioned in January of 1925 and started the fire that destroyed most of the mill.

After the fire, the Harpers Ferry Paper Company (which by this time had been consolidated with the HFEL&P Co. and the Shenandoah Pulp Mill) decided to concentrate solely on the generation of electricity. It is unclear what happened to the equipment and turbines previously devoted to pulp-making. Most of the machinery seems to have either been destroyed in the fire or scrapped afterwards. The water turbines probably survived the fire, but there are no company records as to their disposition. In May of 1925, four months after the fire, the Harpers Ferry Paper Company asked S. Morgan Smith to send someone to test the old Dayton Globe and S. Morgan Smith water turbines used for the electrical plant, presumably to make sure the fire had not damaged them. The GE generator installed in 1917 seems to have survived the fire, although there is conflicting evidence. The company did purchase a new GE 600 kilowatt capacity generator after the fire, and installed it over the 1923 S. Morgan Smith water turbine.

By the end of 1925, then, the Potomac Power Plant had in operation (or soon to be operable) a 1925 GE 600 kilowatt-capacity generator powered by a 1923 S. Morgan Smith 57" vertical water turbine, and a 1917 GE 240 kilowatt-capacity generator connected to a c.1905 Dayton Globe 51" vertical water turbine. The 1925 GE generator was also equipped with a water wheel governor manufactured by the Woodward Governor Company of Illinois. The governor helped to regulate the speed of the turbine by controlling the amount of water entering its runners. According to one historian, the Woodward company dominated the governor market in the 1920s.

It is unclear whether the new GE switchboard installed in 1923 survived the fire, but a 1928 report described the switchboard then in place as a "5 panel G.E. switchboard complete with instruments, switches, bus structure and wiring" plus a "single street lighting panel with instruments, switches and a constant current regulator." At some unknown date, the GE panels were replaced by the Westinghouse switchboard panels currently in the plant.

The major pieces of machinery and equipment in the Potomac Power Plant as of 1998 include the 1925 GE generator with the Woodward governor, the c. 1905 Dayton Globe water turbine, and various Westinghouse switchboard panels.