As I had noted in Volume One, wood had still been used in the construction of floors in most of Chicago’s post-1871 fire commercial buildings that consisted of wooden joists supported on either wrought iron or timber beams, with the few exceptions of the Kendall Building, the Palmer House, and the others that I have reviewed. Concern over the lack of fireproofing for these floors had eventually led to the development of various systems that usually incorporated plaster in one form or another. Besides just covering the wood with an inch or two of plaster, other popular systems included the tubulated plaster casts, May’s patented iron lath, a system of wire lath and concrete developed by Chicagoan James John, and a corrugated sheet iron lath patented by Joseph Gilbert, the inventor of the corrugated sheet iron floor arches that were produced under license by Bouton’s Union Foundry.
Before George Johnson had been forced by the recession to return to New York, he had developed a system similar to his hollow, fireclay tile arches to fireproof wood joists, that evidence suggests that Sanford Loring’s Chicago Terra-Cotta Works had manufactured these that were first used in the roof of the new Chicago Water Works in 1873, where the terra cotta tiles were laid between inverted T-irons.
Johnson’s return to New York in early 1874 had placed Loring and his Chicago Terra Cotta Works in an excellent position to further develop Johnson’s ideas. Loring was issued a patent (#156,361) for “Porous Penetrable Tiles for Plastering” on October 27, 1874, only nineteen days after Drake and Wight had run their test and while Chicago was still without insurance protection. In his patented “porous terra cotta” process, Loring mixed sawdust or other pulverized organic material into the clay that burned away during firing. This resulted in the formation of air pockets relatively evenly dispersed throughout the material that not only gave the material an insulative quality, but also reduced the weight of the finished piece.
The collaboration between Loring and Wight in the development of terra cotta fireproofing systems began to publicly emerge at this point. This was first documented at the 1874 A.I.A. convention, held in New York only days after Drake and Wight’s successful test of their wood-encased iron column on October 8. Wight, now president of Chicago’s A.I.A. Chapter, delivered one of the convention’s papers, “The Fire Question,” in which he not only happily reported the success of the Drake and Wight wood-encased column, but also discussed Loring’s system of porous terra cotta tiles. The key to the future work of Loring and Wight in developing terra cotta fireproofing systems for iron structures was that the furnace that had been built around the three columns in which the necessary fire was maintained so as to conduct the test on October 8, had been constructed in part with Loring’s new porous terra cotta tiles. In his paper, Wight noted that the tiles, even though subjected both to the extreme heat of the fire as well as the cold water used to extinguish the blaze, had remained completely intact. Porous terra cotta’s insulative properties meant that a hollow air space was no longer needed to separate an incombustible covering from the material it was protecting, such as iron. This proved to be a distinct advantage over hardwood and made it logical to replace the wood in Wight’s system with Loring’s porous terra cotta.
Therefore, while the wood-encased column led the way in principle, it was never actually used in a building. Wight’s first terra cotta-encased columns were incorporated late in 1875 in the six-story Chicago Club Building at 12 E. Monroe Street, across the street from the Palmer House, designed by Treat & Foltz as Chicago’s genteel retreat for the likes of Potter Palmer and Marshall Field. While the depression of 1873-9 would slow the adoption of Wight’s invention, it would also give him the time to fully develop it so that it would be ready to use when construction picked up in Chicago during the latter half of 1879.
4.8. SUMMARY: SETTING THE HISTORICAL RECORD STRAIGHT
As I have shown over the course of Volume One, James Bogardus and Daniel Badger had developed the iron skeleton frame in New York during the 1850s. New Yorker Elisha Otis and Bostonian Otis Tufts had begun the development of the elevator during the latter half of the 1850s. New Yorker Henry Hyde had been the first to recognize how the elevator could increase the real estate return of a multistoried office building, i.e., a skyscraper, to offset the increasing cost of Manhattan real estate. George Post had used the iron skeleton frame in New York to erect the interior structures of Hyde’s Equitable Building as well as the taller Western Union Building. The problem with New York’s iron frame that kept it from gaining universal acceptance was iron’s inherent lack of any resistance to the heat of a fire. The solution to this problem, and not the origin of the skyscraper or of iron skeletal framing is Chicago’s true claim to architectural fame.
The essence of the Chicago skeletal-framed skyscraper that evolved during the second half of the 1880s (i.e., “Chicago construction”) was that the iron frame supported its exterior masonry envelope, especially the fireproof covering of the column, completely on the iron frame, thereby relieving the masonry from any load-bearing function. As the Drake and Wight column was the first successful example of a fireproof covering being mechanically attached to an iron column, it is appropriate to note that the Chicago iron skeleton frame had been officially born in October 1874. Its father had been Peter B. Wight. Therefore, Chicago’s fireproofed iron frame was developed not in response to the 1871 fire, as usually stated, (nor by John Van Osdel in the basement of the Palmer House) but instead as a direct response to the threat to discontinue the use of iron columns and the reality of the cancellation of all fire insurance policies throughout the city in October 1874, by the National Board of Underwriters whose actions had resulted from the second fire on July 14, 1874. Peter B. Wight’s application of a thin surface of Sanford Loring’s porous terra cotta to the iron skeleton frame would reduce the function of masonry in a building from load-bearing to that of only fireproofing (and enclosure) that resulted in a lightweight structural system that could finally overcome the limits of Chicago’s weak soil that would unleash the skyscraper to grow in Chicago beyond the traditional height limit of ten stories, once the economy rebounded following the Great Depression of 1873-79.