I can't think of any technological advance that was achieved primarily through the effort of a single individual - in retrospect, it seems "obvious" that the fu

I can't think of any technological advance that was achieved primarily through the effort of a single individual - in retrospect, it seems "obvious" that the fundamental principles had been in place and that it "only" took someone to come along and put them together in a new way. I'm a firearms enthusiast and have spent some time studying the development of small arms. If transported back to the late 18th Century, I could explain and document the mechanism for an automatic rifle suitable for use by infantry like an AR or AK - but I likely could not produce one, and certainly could not produce them on an industrial scale. The metallurgy simply wasn't up to the task, nor was the machinery of the day. The metallic cartridge would't even make a lot of sense; as the percussion cap hadn't yet been invented. Even a manually-operated mounted Gatling gun wouldn't be possible without it. Once a stable, impact-sensitive explosive suitable for use as a primer was invented, everything was in place for the invention of the metallic cartridge - and that's exactly what happened. Metallic cartridges lead to breech-loading firearms, which lead to the bolt action, which in turn lead to automatic and then semi-automatic actions. Neither of the last two made much sense until the invention and adoption of smokeless powder, as traditional gunpowder leaves so much residue that it would only work for a few shots before "fouling". All that said, there are individuals that push the state of the art forward a great deal through their contributions. John Moses Browning, for instance. He created the first gas-operated machinegun and several of his designs remain in use (essentially unchanged) by major militaries around the world more than a century later.