This piece is part of the Sidewalk Talk series "15 Innovations That Shaped the City."
The rise of large cities in the 19th century made fire control a critical new element of urban governance. One fire in New York City in 1835 wiped out nearly 20 city blocks; an 1851 San Francisco blaze destroyed more than a quarter of the city; the Great Chicago Fire of 1871 claimed nearly 300 lives. But by the 1930s, large destructive fires had become a rarity, thanks to a suite of innovations and regulations. "Block and group fires are rare today," writes Bruce Hensler, author of Crucible of Fire: Nineteenth Century Urban Fires and the Making of the Modern Fire Service. "They are rare because of what firefighters and the fire insurance industry learned in the nineteenth- and twentieth-century American city."
Ctesibius, a 3rd-century B.C. Greek inventor and mathematician, invented the first piston pump that could produce a jet of water propelled by compressed air—a fundamental advance that, with modern improvements, continues to be used today.
Imperial Rome, meanwhile, was the first civilization to enact mandatory building codes aimed at suppressing fires. After a devastating fire in 1st-century Rome, the emperor Nero ordered the city to be rebuilt with more non-combustible materials. Wooden structures gave way to those made of brick and stone, and empty areas between dwellings prevented many house fires from spreading to adjacent dwellings.
Until the Industrial Revolution, most firefighting technologies were modest attempts to control large urban fires that had already broken out. For many cities the fire "department" was the old bucket brigade. It took the machine age to develop a series of breakthrough technologies and fire prevention strategies that, taken together, would save millions of lives, protect cities from being destroyed, and transform urban building design.
First was the development of stringent fire codes for buildings. A huge 1845 fire in New York City demonstrated that even modest building restrictions were effective, as the fire stalled out when it reached areas rebuilt with stone, masonry, iron roofs, and metal shutters. After the Great Chicago Fire, the iron and steel industry developed new ways to forge fireproof iron columns and steel-frame buildings that could withstand much more heat, giving rise to Chicago's skyscrapers.
Next was the debut of the portable fire extinguisher, an invention that put out innumerable small fires before they got big. While cities experimented with early versions of soda-acid and glass grenade extinguishers emerged in the late 1800s, it wasn't until 1912 that Delaware-based Pyrene Company perfected the carbon tetrachloride extinguisher—a brass container containing fire-suppressing liquid that inhibiting the chemical reaction of the combustion process.
The emergence of fire escapes and emergency exits helped city planners think about life-saving capabilities on a larger scale. In 1903, the Iroquois Theater Fire in Chicago killed 602 people, with panicked theatergoers crushed trying to escape because nearly all of the theater's exit doors opened inward. The tragedy gave rise to the panic bar, the now-familiar trigger mechanism that allows users to open a door outward.
In the late 19th century, a New Jersey-based inventor, William Watkins, developed the heat-sensing automatic fire alarm, which automatically sent telegraph signals to the fire department when the hardware detected temperatures higher than a specified threshold, eliminating the need for people to report a fire. At the heart of the invention was what came to be known as the "Watkins thermostat," a unit that contained thin strips of metal that acted as heat detectors.
Arguably, the most effective modern fire-safety innovation has been the automatic sprinkler—a valve-controlled system that was activated by the melting of solder, patented in 1881 by inventor Frederick Grinnell. (In France, a sprinkler is still often called "le Grinnell.") Insurance companies and building owners were early adopters of the technology, seeing an effective and low-cost means to douse small fires before they spread.
Each of those advances contributed to much safer cities over the last 100 years.
Stricter building codes have saved thousands of buildings and greatly reduced the area of destruction caused by a single fire. The panic bar has eliminated the horror of people being crushed trying to exit large venues during a fire. (The Oakland warehouse fire in 2016, which killed 36 people, stands as a tragic example of what can still happen when building codes are ignored.) It's estimated that fire extinguishers put out more than five million fires annually in the U.S. Sprinklers reduce the chances of a fatality in a structural fire by 50-75 percent and average property loss per fire by 50-66 percent, according to the National Fire Protection Association.
Building codes are still evolving, too. For example, more robust fireproofing is required for buildings more than 75 feet tall, using materials that will be less likely to be dislodged by impacts or explosions. Additionally, radio coverage systems within buildings have been standardized to allow emergency personnel to better communicate within the building and with emergency responders outside the building.
Firefighting technology continues to expand. Recent advances include "Sensor-Assisted Fire Fighting," which feeds data taken from sensors located in burning buildings into computer models so that rescue services can accurately predict how fires will spread.
Most major urban fires these days result from a failure to comply with existing fire regulations. For example, the June 2017 blaze at a 24-story London apartment building that killed at least 80 people spread out of control largely because the building's exterior cladding was not sufficiently fireproof. But on the whole, firefighting advances have made large fires so rare in urban areas that some fire departments are reducing the size of their fire engines to better fit within narrow city streets—the great big trucks just aren't as necessary today as they were in the past.