The introduction of steam power in the two decades before the Civil War freed the Armory from dependence on an uncertain waterpower and made it possible to transfer some manufacturing operations to the Hill shops. The Water shops remained important, however, and their efficiency was increased by combining all activities at the Upper Water Shops site.
Relying on a steam engine as a central power source required energy to be transferred to individual machines, resulting in the profusion of belts and shafts that characterizes late-nineteenth century shops. Meanwhile, the machines themselves were being steadily improved, making it possible to work to finer tolerances. These changes were accompanied by the development of more exact measuring devices, such as the screw micrometer and the headspace gauge.