In 1902 George Darby of England patented a fire alarm made from butter... It sounded an alarm when the butter melted!

Installing a fire detector in your home will halve the chance of a fatal fire. Invented in the late 1960s, the fire detector is believed to have saved thousands of lives worldwide. Fire detectors, together with the fire extinguisher, are among the most effective tools against fire.

Duane Darwin "Dewey" Pearsall (March 3, 1922 – April 11, 2010) was an American entrepreneur best known for developing and marketing the first battery-powered home smoke detector in 1965.

The first example of modern fire detectors was invented in 1902 by George Darby, a British electrical engineer. Darby's invention sensed heat rather than smoke and consisted of two electrical plates with butter in between. The rise in room temperature caused the butter to melt, triggering the alarm as a result of the plates touching each other. Of course, this meant that the melted butter was scattering everywhere.

The most commonly used fire detectors today contain an ionization chamber. Developed by the Swedish physicist Ernst Meili in 1939, this device was used especially for the pre-detection of toxic gases in mines. Although these gases did not produce smoke every time, the radioactive substances caused the formation of electrically charged atoms called ions. When smoke entered the work, the flow of ions between these two electrodes was disrupted and this caused the alarm connected to the system to be triggered.

Although the ionization chamber fire detector was used in the 1950s, these devices were expensive and were used only in factories or large buildings. Duane Pearsall, an American born in 1922, is known as the person who invented the first fire detector, which can also be used in homes, in 1967. Pearsall's fire detector houses a smaller ionization chamber, which includes a battery. Two other Americans, Kenneth House and Randolph Smith, patented the battery-operated fire detector in 1969. Even a method used in a space program implemented by the American National Aeronautics and Space Administration (NASA) is believed to have played a role in the development of fire detectors. In fact, NASA developed a type of detector as part of the Skylab project, but did not invent the detector itself.