The Business End of a Screwpile

The Business End of a Screwpile. . Screwpile lighthouses like Drum Point get their name from the pilings which were screwed into the seabed to support the lighthouse structure. This cast-iron auger and attached section of wrought-iron pile were recovered from the original site of Drum Point Lighthouse in 2001., Screwpile lighthouses were first developed by Irish engineer Alexander Mitchell, who patented his invention in 1833. Screwpiles became widely used throughout the world as a foundation system for piers and bridge as well as lighthouses., Surprisingly, little has come to light describing how the heavy plies were supported and driven at the precise angles required. In earlier years, a barge-mounted capstan, rotated by a team of men, drove the piles. It is known, however, that the seven piles that supported Drum Point Lighthouse were set in the remarkably short time of three days., CMM 2001.17, [Captions:] , Lighthouse Depot, Lazaretto Point, Baltimore , Much of the ironwork, manufactured at the Allentown Rolling Mills, was numbered to aid in construction when on-site. Materials for the construction of the lighthouse were assembled at the United States Lighthouse Establishment's Lazaretto Depot in Baltimore. This view shows the depot in later years. , RG 26, National Archives at College Park, College Park, MD., U.S.L.H.E. Tender Jessamine , The lighthouse tender Jessamine, built in 1881, helped transport the materials and work crew to the site of Drum Point Lighthouse in 1883. , Courtesy, U.S. Coast Guard Historian's Office, Washington, D.C.