This report is an extension of work to demonstrate the effectiveness of cooling tower drift instrumentation which Environmental Systems had developed up to that point in time. The prime instrumentation discussed was the Particulate Instrumentation by Laser Light Scattering (PILLS I) system. At the time, an explicit calibration of PILLS I using water droplets had not been performed. The report discusses primarily an explicit calibration of the PILLS II istrument which is an update of the PILLS I. It describes the PILLS II generation equipment, its calibrations and data interpretation procedures. The describing equations for PILLS are given, along with the defining equations relevant to the drift properties measured. These latter equations are of general utility and are independent of measurement techniques.