The steam engine may very well have been the greatest technological achievement before the twentieth century. It really did set the stage for much of what we know about mechanical engineering.
But sometimes, those engines overheated and caused entire trains to explode. Countless lives were taken because of this phenomenon. Because this isn't really a thing anymore, you can get an idea of the magnitude of these explosions in the photos below.
James Watt patented a steam engine with a continuous rotary motion in 1781, but it wasn't until 1815 that we started using them on trains. That same year, the first boiler explosion took place on a locomotive in Philadelphia, killing 16 people.
It was the first locomotive explosion, and it also produced the most deaths of any railway explosion ever.
Boilers often exploded when cool water was added to hot engines.
This train exploded on Christmas Day, 1931. Notice the superheater tubes that make it look like some kind of Cthulhu monster.
Because of a defective safety valve, this train exploded in Florida in 1911. The train's bell was found a mile away.
The good news is that engines exploded so frequently that it gave America the incentive to start the practice of testing materials.
Although we live in the age of the electric motor, a ton of energy is still generated with steam around the world today. Fortunately, steam engines have come a long way since then. Failures of the past have given way to so many improvements.