I was always intrigued by the origin of the spark plug. The gasoline engine development depended on it (until German inventor Rudolf Diesel came with his bright idea in 1893). As a youngster I understood how the engine worked – I started at 14 years old taking them apart – and not to take anything away from those savant engineers and scientists who invented the principle of operation and produced unbelievable results, but all of it depended on someone who could develop a product that could make a spark to create that ball of fire (kernel) to expand the gas vapour virtually instantly under very demanding parameters of high pressures and heat. Along came a Frenchman in 1860 by the name of Etienne Lenoir who used an electric spark plug in his gas engine, the first practical internal combustion piston engine patented that year, and is generally credited with the invention of the spark plug. He obtained a patent (patent no 345596) in 1886 the same year he obtained a patent for a carburetor. Click on the link Spark Plugs  for more about the story