Answer:
1. Florence Nightingale collected information on the mortality causes in soldiers, resulting in developments in military medical care.
2. Robert Koch deduced a procedure for convincingly finding the etiology of the disease.
3. Joseph Lister demonstrated that infection rates by the surgical wound could get diminished dramatically with the application of carbolic acid to disinfect bandages, surgical tools, and surgical sites.
4. John Snow found the cause of the cholera outburst in London.