On Dec. 30, 1903, a crowd of nearly 2,000 people squeezed into Chicago’s new Iroquois Theatre, which had been proclaimed “fireproof beyond all doubt” by the local fire inspector and Chicago’s building commissioner just a few weeks earlier. School was out for the winter holidays, so the majority of the audience members were children with their mothers.
The Iroquois Theatre, 1903 | Courtesy of the University of Illinois.
During the second act of the show, a play called Mr. Bluebeard, an overheated arc light backstage ignited a stage curtain. From that moment on, everything that could go wrong did go wrong. The asbestos fire curtain malfunctioned and didn’t descend to block the flames. A fire extinguisher did nothing to quench the fire, and soon the flaming curtain fell onto the stage. The actors ran off stage and out the back door. The audience began panicking and rushing for the theater’s 30 exits. Unfortunately, nearly all of the doors were inaccessible: few were marked, some were obscured by drapes and others had been locked from the outside to prevent gate-crashers.
Hundreds succumbed to the smoke, fell to their deaths from the balcony or got crushed in the ensuing stampede. By the time the fire department managed to break their way into the theater, an eerie silence had descended. Firefighters called out for survivors, but no one answered. In total, more than 600 people died, many of them children. Actor Eddie Foy, who stayed on the stage and tried to calm the crowd, estimated that 500 of the deaths occurred in just eight minutes.
The aftermath of the fire, 1903 | Library of Congress
It is not surprising that this horrible tragedy shocked Chicago, the United States and the world at large, as it highlighted the need for more stringent safety regulations.
What may be surprising, however, is that the Iroquois Theatre Fire played a major role in UL’s history. This Chicago tragedy and other similar disasters in the early 20th century led to the creation of the UL Mark — a symbol of safety to consumers for over 100 years. But to truly understand how the two pieces fit together, we need to go back to the very beginning of UL’s story.
1894-1904: Pre-UL Mark
The UL Mark almost wasn’t the “UL” Mark at all – UL’s original initials were actually UEB! When William Henry Merrill Jr. opened his first laboratory in 1894, it was called the Underwriters’ Electrical Bureau. Over the course of the 1890s, this name gradually evolved into “Underwriters’ Laboratories.” In 1901, the organization incorporated in the state of Illinois as Underwriters’ Laboratories, Inc.
William Henry Merrill Jr. completed UL's first test report in March 1894. At the time, UL's name was the "Underwriters' Electrical Bureau." | UL Archives
In those early days, UL’s work primarily consisted of testing products and materials and then publishing reports on the results of the testing. A directory of all the “certified” devices would be published on a semi-annual basis, and the idea was that a consumer interested in purchasing a UL tested product could look at the directory of certified items and select a device off of the list. However, a problem with this system quickly arose.
At first, Merrill and his engineers simply stopped by factories to check up on certified devices. But as the work of the Laboratories grew, it became clear that there was a need for a formal follow-up inspection schedule. UL employees found themselves asking what would happen if an unscrupulous manufacturer decided to swap out a part, substitute cheaper materials or cut corners during the production process. This could mean that unsafe versions of certified devices would make it out into the marketplace – and the name “Underwriters’ Laboratories” would mean nothing for safety.
1904-1906: The beginning
To address these issues, UL’s Reexamination Service was created in 1904. It consisted of annual reexaminations of UL certified devices and materials. Additionally, manufacturers had to sign a contract agreeing that they would construct their devices in the exact same way as the certified sample had been constructed. However, it soon became clear that certain products required a closer eye than a single annual reexamination.
In one anecdote that has been handed down through generations of UL employees, two fire extinguisher manufacturers met outside of UL’s headquarters sometime in 1906.
The two rivals sized each other up.
“That’s a mighty fancy-looking fire extinguisher,” one remarked to the other. “How do you expect to produce it at a profit?”
“Oh, I don’t,” replied the other. “This is a special sample for Underwriters’ Laboratories to test.”
As the story goes, Merrill happened to overhear this conversation. Of course, he wasn’t pleased with the idea of manufacturers bringing “special samples” to UL for testing, and he decided to do something about it.
As a result, he created the Label Service Department, which was comprised of inspectors whose sole job was to visit factories on a regular basis and inspect UL certified products during the production process. Once the inspector confirmed that the product had been constructed according to UL’s rigorous safety requirements, a label would be placed on the product. This label would bear the marking “Underwriters’ Laboratories,” and a consumer would know that it was safe to buy and use. This was the birth of the UL Mark.
Which takes us back to the Iroquois Theatre in 1903.
“… whose lives were sacrificed that a man might make a profit of two dollars.”
Being a Chicago company, the Iroquois Theatre fire hit close to home at UL. Following the tragedy, John Ripley Freeman, the president of the American Society of Mechanical Engineers, compiled a famous report called On the Safeguarding of Life in Theaters. UL assisted in the report by hosting a series of tests on fireproof curtains and sharing research on fireproof paints with Freeman.
Merrill was also struck by the failure of the fire extinguisher to work as it was supposed to. The owners of the Iroquois had thought that they were adequately protected against fire because they owned a fire extinguisher. However, a later report revealed that the Iroquois Theatre’s fire extinguisher was a mere “ten cent’s worth of baking soda in a five-cent tin tube.”
William Henry Merrill Jr. | Popular Electricity, November 1911
Merrill sharply criticized this, saying:
"… A man put ten cents’ worth of baking soda in a five-cent tin tube. He sold it for three dollars as a fire extinguisher to use in … the Iroquois Theater in Chicago. The operator testified that the fire in its incipiency could have easily been extinguished by a small stream of water … he waved [the extinguisher] as directed, expecting the magic wand to be effective in such surroundings. Unfortunately, there was nothing “make-believe” about the fire, and the result was, and always will be, very real to the families and the friends of over six hundred women and children, whose lives were sacrificed that a man might make a profit of two dollars."
Organizations like the U.S. Consumer Product Safety Commission (CPSC) did not exist yet, and there was no organized system for product recalls. How could UL help ensure that consumers weren’t buying ineffective fire extinguishers?
Although UL was publishing lists of certified fire extinguishers, most consumers were not carrying that list around when they were shopping. The Lists were predominantly used by underwriters and building inspectors. Merrill decided that there needed to be an easier way for people to pick out tested products – something that wouldn’t require extra work or special knowledge on the part of the consumer.
Hence, the introduction of the UL label.
The Reexamination Service still existed, and it covered products that used molds and weren’t likely to have production variances and defects. The Label Service would cover products that had a “life safety” purpose and needed more frequent oversight, such as fire extinguishers, fire sprinklers and fire alarms.
On the left, Left, a Label Service inspector oversees the construction of a tin-clad fire door. Once the inspector determines that the door has been safely constructed, the door receives a label bearing the name "Underwriters’ Laboratories." At right, an engineer tests a fire extinguisher. | Symbol of Safety, 1923
The development of UL’s follow-up services program in the early 1900s shows Merrill’s passion for improving UL’s ability to promote safe working and living environments for people everywhere. UL did not simply sit by placidly when disasters like the Iroquois Theatre fire occurred; rather, the organization mobilized and did whatever it could to ensure that a similar tragedy would not strike twice.
Because of events like the Iroquois Theatre fire, the first labels were for products like fire extinguishers. There were also labels for conduit, window frames for wired glass and wiring. In 1907, Merrill wrote that UL was planning on extending its Label Service to hoses, watchmen’s time detectors, fire doors, insulating joints and other fittings used in fire protection. Back then, the sale of labels could be tracked in a single ledger. Today, UL Marks appear annually on more than 22 billion products worldwide.
The List of tested fire extinguishers prior to the existence of the UL label. 1905 | UL Archives
The label takes on the appearance of the familiar brass plate that appears on many extinguishers from this time period, 1907 | UL Archives
The table of contents in the first label ledger, which Merrill used to record label sales between 1906 and 1908. | UL Archives