a vertical position. The web of the I-beam fit into a horizontal slot between two lugs. It is also known that, at the ends of the bridge, only half of each angle block received load because Stone used only a single diagonal in the end panel. This put enormous shear stress on the bridgeward side of these angle blocks. Construction The Ashtabula River bridge was erected in 1865 using Stone's design and plans and partly under his supervision. Tomlinson was the bridge's original construction supervisor, but Stone said he fired him for "inefficiency" at some point during the bridge's construction. Tomlinson was replaced by A. L. Rogers. When construction began, Tomlinson observed that the I-beams intended for use as diagonals were smaller than the fabrication plans called for. The amount of camber created a problem during construction. At Congdon's suggestion, Rogers built falsework to support construction of a bridge with a camber. Stone, now himself supervising Rogers' work, ordered the camber reduced to . With the members of the upper chord now too long, Rogers had the bearings shaved down. It is clear Rogers ordered other changes as well, but it is uncertain what these included. Gasparini and Fields suggest he had the lugs atop the angle block planed down as well. When the falsework began to be removed, the dead load caused the bridge to bend about below horizontal. The bridge was jacked up and the falsework put back in place. Stone then ordered the chord members to be returned to their original lengths, restoring Tomlinson's intended camber. Rather than ordering new I-beams, Rogers used shims to close the space between the bearings and the lugs. When the falsework was removed a second time, the bridge buckled where the vertical posts connected to the deck. Several diagonals also buckled. Once more, the falsework went back in place. To correct this problem, Stone added more iron I-beams to the diagonals to strengthen them. The placement, size, and number of beams added is not clear, but Stone likely added two I-beams to the brace in the end panel, two I-beams to the brace in the first panel from the end, and one I-beam to the second panel from the end. This worsened the bridge's dead load problem. Collins, Congdon, Rogers, and Stone all later testified that the I-beams making up the diagonals were now turned 90 degrees, so that the flanges