One of the early advocates of bacteriology was Percy Frankland (1858– 1946), who worked with his father at the School of Mines, where he was an assistant in the water laboratory. After learning of the plate culturing method at an exhibition in London, he visited Koch’s laboratory to master this new method. Frankland used the method from 1885 onward to measure the numbers of bacteria in water and evaluate the efficiency of filtration. He observed what is now well established: filters are effective for the removal of bacteria, they lose their efficiency with time, and smaller filters become clogged and support bacterial growth. In his words, this was an “exceedingly beautiful and ingenious test for ascertaining the number of individual organisms present in a given water,” with “little value” for distinguishing bacterial types (quoted in Hamlyn 1990). Overall, more and more people agreed that plate cultures showed the value of filtration in removing microorganisms. Many questions on these methods were also raised at the time; surprisingly, they are still familiar even to modern water bacteriologists. Was gelatin-peptone the best medium? What was the sensitivity of the medium for waterborne pathogens? Comparison of media and their ability to support pathogens became a familiar exercise. Lower counts on nutrient-rich media and upon incubation at “blood temperature” were observed, as was the poor growth of pathogens on nutrient-poor media.