Original copper photoengraving letterpress block depicting a monumental arched dam structure in the final stage of construction — one of the printing plates used to produce the January 1, 1915 promotional booklet of the H.P. Cummings Construction Co., general contractors of Ware, Massachusetts, whose headline specialties were dams, hydro-electric power plants, and heavy concrete work across New England. The image is a striking piece of engineering photography: a rank of tall round arches spanning the riverbed, freshly stripped of formwork, carrying the crest works overhead; massive raw concrete abutments in the foreground; timber staging and railings still in place along the top; a long sluice pipe cutting diagonally across the scene; and construction rubble scattered over the ledges below — the job caught just before the water was turned in. Where most surviving imagery of the water-power age shows finished installations, this plate preserves the construction moment itself. The halftone copper plate is mounted type-high on a wood base. The booklet this block printed survives in the collection of Historic New England and is viewable online through Digital Commonwealth, making the plate and its published page traceable across more than a century. Honest age with oxidation, toning, and shop wear from press use. See ruler in photos. A compelling piece for collectors of civil engineering and dam-building history, construction photography, New England industrial heritage, or letterpress and printing arts.