On August 27, 1883, the volcanic island of Krakatoa in the Sunda Strait exploded with unimaginable violence, generating an acoustic blast considered the loudest sound in recorded human history. While the audible roar traveled thousands of miles across the Indian Ocean, an invisible force weaponized the Earth's atmosphere: a massive atmospheric barometric wave. Travelling at nearly the speed of sound, this shockwave traversed the entire globe multiple times over several days.
In London, over 7,000 miles away from the cataclysm, people felt nothing out of the ordinary, yet industrial instruments quietly captured the planetary disturbance. Gasworks across the British metropolis were equipped with automated, self-registering gasometer pressure gauges designed to track micro-fluctuations in coal gas storage and distribution pressure. As the invisible air pressure crest from Krakatoa washed over England, it squeezed the colossal iron gasometer drums floating in their water seals.
This sudden, tiny increase in atmospheric load forced the gas pressure inside the containers to spike. Automated mechanical stylus pens attached to float gauges recorded sharp, unexplained vertical spikes on their rotating paper charts. Meteorologists and physical scientists soon gathered recording strips from gasworks across Europe, discovering identical pressure spikes repeating roughly every 36 hours as the wave echoed back and forth between antipodes.
This unexpected network of industrial sensors provided scientists with their first comprehensive, empirically recorded continuous proof of global atmospheric shockwave propagation.