They were collecting data. The theory had already been worked out at that point, but it required data to be put to use. I think this does broadly fit within the

They were collecting data. The theory had already been worked out at that point, but it required data to be put to use. I think this does broadly fit within the framework of Popperian falsification that OP is describing. But I'd also agree that classification and data gathering, as well as hypthothesis generation are of course all vital parts of the scientific process. It is worth noting though that a surprisingly large number of scientists have issues grokking or putting into action the concept of 'falsifying the null hypothesis'.