mudboy dave:
Sorry for the tardy response to your query, but I have not posted for a several weeks. Regarding the company for which you seek information, Jacob Steinmetz Thorn, born on 1 August 1836, began his business career as a clerk for the iron merchant firm of Martin and Smith in 1855. Two years later, he went to work for Moore, Henzey & Company. He remained there but a short time before obtaining a position with the architectural iron business of J.P. Stidham & Company and their successors, the Philadelphia Architectural Iron Company. During his tenure with this company, Thorn engaged in negotiating many large building contracts and managed the construction of several prominent buildings. In 1878 he purchased the Philadelphia Architectural Iron Company after the former owners retired from the business. He restyled the company as the J.S. Thorn Company and established a new production facility at 12th and Callowhill streets, where the business flourished. According to an 1881 Philadelphia City Directory, the company occupied a complex of buildings located at 1203 to 1209 Callowhill Street and specialized in “metal cornices, cast zinc, ornamental work, and builders’ light iron work,” so fabricating with and forming sheet metal became a real specialty for the company. Thorn’s employment rolls grew to several hundred workers as his products proved to be in demand. In addition to the J.S. Thorn Company, Jacob also served as president of the Thorn Shingle and Ornament Company and the Vulcan Company by 1904. He held several patents, gained in the 1880s, for interlocking sheet-metal roofing tiles. Steel window units, including one that operated automatically, also proved a specialty and he received a patent for them in 1902. Although Thorn died on 2 March 1910 in Savannah, Georgia while on a business trip, the company continued operations until the Great Depression caused the company to enter bankruptcy and close down.
The tin-clad door you observed in the boiler house is a transitional fire-resistant door before all metal doors became commonly available. The theory behind constructing such doors is that the tinned metal would provide a set time of protection before the wood core would heat sufficiently and burst into flames. Hopefully, firefighters would extinguish any blaze before the wood inside the metal would combust. Fire insurance and factory mutual companies developed such fire-resistant doors in an effort to stem losses from major conflagrations. Generally, the naked, tinned finish of the sheet metal would resist the fire better than if the door had received a coat of paint. Likewise, sheet iron, galvanized iron and other types of sheet metal did not offer the same fire protection as tin-clad doors due to a lower resistance to fire. No nail heads could protrude from the door as the nails would act as a heat sink into the wood. The tin sheets had to be lock-jointed in order to work efficiently and no wood could be exposed to the air and potential fire. The insurance companies would not permit soldered joints as the flames would cause the solder to melt and the plates fall from the door. Although many of these types of doors remain in place, all metal doors eventually supplanted them. Visits to old manufacturing complexes, and especially the boiler houses, will demonstrate that these types of doors still survive in goodly quantities and will continue to function as designed as long as the tin sheets are properly maintained.
Best regards,
Jerseyman
