But Philadelphia still had an opportunity with the Fair to erect the tallest structure in the world. It seems obvious today that buildings, especially those planned as speculative investments to include rentable office space, could not continue to employ the masonry bearing wall, and still be profitable. The only structural alternative to the solid masonry tower of Philadelphia’s City Hall, the iron skeleton frame, was to be used in a proposed 1000’ tall tower, while the foundations for the City Hall’s tower were being laid and before the first block of stone was put in place. Late in 1873, David Reeves of the Clarke and Reeves Phoenix Iron Works in Phoenixville, Pennsylvania, (some twenty-two miles northeast of Philadelphia, the route of which goes through the poignantly named town of King of Prussia) proposed to build a 1000’ observation tower for the upcoming World’s Fair.
His father, Samuel Reeves, had patented a fabricated wrought iron column in 1862 named the Phoenix column, that consisted of flanged rolled sections that were bolted or riveted together to form a circular hollow cross-section with vertical stiffeners. These were being used in bridges, viaducts and the interiors of buildings by 1873.
The major concern of such a tall structure would have been wind loads, so the structure’s surface was accordingly minimized. An inclined open framework of 30-foot long Phoenix columns that were diagonally braced by smaller iron tubes rose for 32 layers that decreased in diameter from 150 feet at the base to 40 feet at the top. Four elevators to the viewing platforms at the top were located in the center 30-foot diameter cylindrical shaft that also supported a spiral staircase.
Its design was prophetic not only in its extensive wind bracing system, but also in its innovative, ahistoric appearance. Unfortunately, Philadelphia never got its chance at the tallest structure in the world for it was another casualty of Philadelphia’s own Jay Cooke’s bankruptcy.
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The Architecture Professor 