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Chapter 3 Iron and Light: The “Great Architectural Problem” and the Skeleton Frame, 1879–1892 Iron structures protected by terra-cotta offered hope against conflagration, but they also enabled interiors that were more spatially efficient and better illuminated than pure masonry structures. Masonry’s low compressive strength made for large, space-consuming piers that congested floor plans, especially on lower levels where owners typically desired more open retail spaces. It also meant thick, solid exterior walls that restricted natural light. Iron offered solutions to both problems. It required less cross-sectional area than brick or stone for a given load, which allowed smaller interior columns and thus more open and flexible floors. But architects began to recognize that it could also take some—or even all—of the loads carried by exterior walls. For centuries, brick walls had performed key structural duties and had been treated as massive, planar elements, inside of which lighter structures could form more delicate, skeletal counterparts. But the application of fi eproofed iron to building exteriors provoked a wholesale change in the conception of exterior walls, building on the examples of nascent skeletal structures in cast-iron storefronts and facades. If exterior bearing walls could into skeletal, iron grids—then they could be more porous, with larger apertures that were restricted only by the bearing capacities of iron rather than brick. Like the more efficient floor plates inside , structure would take up far less space in such elevations, leaving more room for windows. The emergence of Experience has demonstrated that all spaces within the enclosure of four walls which are not well lighted by sunshine, or at least direct daylight, are in office buildings non-productive. —John Wellborn Root,“A Great Architectural Problem,”1890 be reconfigu ed in much the same way as interior structures—if their loads, too, could be organized and channeled the skeleton frame can be understood as the migration of fi eproofed iron to the edges of the building, bringing with 36 • Chapter 3 it the efficiency and the constructive logic of this new hybrid construction. It also brought with it unprecedented aesthetic opportunities. Precond itions: Li gh ting John Root’s “Great Architectural Problem ” noted that illumination was the fundamental issue facing Chicago’s commercial architects, even more than weight or foundation capacity.1 While advances had been made in interior lighting through the 1880s, daylighting remained the most widespread solution to illuminating commercial interiors through the early twentieth century . Candles and oil lamps remained in use, though by the time of Root’s essay in 1890 they were supplemented by illuminating gas, which doubled brightness to about eight candlepower.2 Electricity became available in Chicago in the mid-1880s, but the very real possibility of electrocution—often described in lurid news reports—and the high cost of generating equipment made it an expensive and risky luxury until the turn of the century. The inefficiencies of oil and gas lighting were compounded by the inherent dangers of open flame; in 1884, the majority of fi e fighting calls in Chicago involved overturned or exploding oil lamps.3 Illuminating gas, usually manufactured from coal, presented a partial solution through fixed wall- or ceiling-mounted lamps. In 1850 the Chicago Gas Light and Coke Company built a network of pipes, gasometers, and distilling plants to provide public lighting along Lake Street and they enjoyed a monopoly over illuminating gas throughout the city. The quality of its gas was variable, however, and its prices were extortionate until the People’s Gas Company provided much-needed competition in 1885.4 People’s Gas offered a cheaper, cleaner product, but claims by each company about dangers in the others’ gas meant that by the 1890s gas lighting had earned a reputation in Chicago as “decadent” and archaic. There were, however, few alternatives to gas or oil.5 John Barrett demonstrated an “unsteady but very powerful” electric arc light at Chicago ’s Water Tower in 1878, and Edison’s 1882 installation of a central generating plant in New York aroused Chicago’s expectations for electrification. Chicago illuminated the streets and tunnels around City Hall with $42,000 worth of Edison lamps and dynamos in 1885, but they took two years to install, and this delay was seized upon by gas interests as evidence that electricity was a mere novelty.6 Incompetent contractors and faulty work abounded, particularly where inferior wiring could be concealed behind plaster.7 More importantly, electricity was expensive to install, provide, and maintain...

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