US Patent No. 518,274, granted April 17, 1894 to Charles A. Praray of Providence, Rhode Island, for an improved building construction aimed at mills and other large buildings. Iron columns on separate piers carry the floor beams, while the outer walls, with bayed surfaces and pilasters, stand on their own foundations and carry no floor load. The patent includes a drawing sheet with six figures, a specification and five claims; the advantages cited are cheaper walls, more window space, easier removal of walls after a fire, and protection of beam ends from rot.