To wit, consider the case of Charles Parsons, inventor of the steam turbine engine. He was able to do this because of the lifetime work of Henri Victor Regnault (https://en.wikipedia.org/wiki/Henri_Victor_Regnault) characterizing the behavior of steam under pretty much every possible regime. At the time Regnault's work was largely ignored, and later forgotten, since it was only of minor academic interest.

It was only years after his death that Parsons would use his work to determine the necessary geometry of the rotors and stators in his new and revolutionary engine. Regnault certainly didn't see that coming, the people who overlooked his work didn't either, but that pure science for the sake of science helped to change the world.

So as you say, we often don't realize what we're going to do with the results of pure science until engineering catches up, sometimes decades or centuries later. Still without the pure science we'd never get the engineering.