The elaborate brickwork and crenellated parapet of this building heralded its importance in supplying power to the site. It was originally fitted with a single-cylinder, beam steam engine with ornamental Gothic tracery (according to an 1855 description) manufactured by the A. N. Miller Foundry in Savannah. The present single-cylinder, horizontal steam engine, manufactured by the Findley Iron Works in Macon, is authentic to the period but was installed in the 1990s. The boiler opposite the engine is also not the original. An interior wall once divided the engine room from the boiler room, while the space along the south side of the building was used to store wooden mold-making patterns for casting iron parts. The steam engine powered the line shaft system for the repair shop complex. The line shaft exited through openings visible at the tops of the east and west walls, and the entire system, which operated continuously, extended east through the blacksmith and machine shops and west through the carpentry shop to power machinery from the shafts via individual drive belts. The steam engine remained in service until 1907 when the line shaft was motorized and an electrical power plant was installed in the adjacent lumber storage shed to the west. The boiler continued to power the steam hammer in the blacksmith shop (7.1.9) and a compressor that supplied air to the shops and engine house. Machinery was gradually motorized with individual motors until the line shaft system was finally retired in 1923. A powered line shaft display with drive belts running the machinery is located in the blacksmith shop.