In recent years, the field of public health has experienced a great influx of specialists. Prior to 1910, medicine and nursing were almost the sole professions within the health department. At that time medicine was almost entirely clinical. As preventive medicine developed it was imperative to enlist the services of many scientific disciplines in a cooperative attack upon the complex problems of modern public health. Thus we now find that the dentist, the sanitary engineer, the bacteriologist, the mycologist, the virologist, the physicist and may others have a definite place in the field of preventive medicine.
As each of these professions has increased its activity in research and field operations for the control and prevention of disease, it has had to reach for new tools with which to perform its task. Today an examination will show that a surprising proportion of these tools are not biological, statistical or diagnostic in nature but are instead purely physical tools, apparatus and equipment.