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Stlrren: Initial operation of the system showed that temperature gradients were established from the coil to the water surface. The gradient caused only a slight decrease of 1-2 degrees on the water surface with a decrease of 5-15 degrees next to the coils. Wilkins-Anderson (Waco Supreme) labora- tory stirrers were therefore installed on the side of the pan to circulate (destratify) the cooled water uniformly. The slow-speed. two-bladed prop caused nlinimal surface disturbances in a small area adjacent to the shaft. A stirrer was also mounted on the normal pan to keep conditions uniform between the three pans. These stirrers eliminated the temperature gradient and kept the pans constantly mixed. Temperature recording Re<Order: A Sanborn eight channel D.C. amplifier recorder was used to monitor air and water temperatures. It featured general purpose resistance measurements and recording on eight separate 5 centimeter channels fed from a single roll chart. A timing circuit was connected to the Sanborn recorder to take readings at 20 minute intervals. All eight channels were used to monitor resistances for these temperatures as follows: 1. North pan surface temperature 2. North pan bottom temperature 3. Center pan bottom temperature 4. Cenler pan surface temperature 5. South pan surface temperature 6. South pan bottom temperature 7. Air temperature 8. Dew point Channel calibrations were made in DC to allow the reading of temperatures directly from the chart. ThermIBton: Yellow Springs Instrument Thermistors (No. 44033) were used for all temperature measurements. The air temperature thennistors was placed inside an instrument shelter and all of the water temperature thermistors were mounted on brackets 1 inch away from the side of lhe pan. The surface thermistor was approximately I inch below the water surface; the bottom thermistor was 1 inch above the cooling coils. The thermistors were mounted on the shady side of the pan to avoid any direct solar radiation. All thermistors and electrical equipment were con- necled to a coaxial cable which linked them to the Sanborn recorder and power supplies. housed in a nearby equipment shed. CaIlbradoD: All eight channels were calibrated at the start of a daily recor~. A resistance circuit was designed to cover the daily temperature ranges. These resistances came from calibration curves included with each thermistor. Readings were initially tested against accurate thermometers. The verified calibration marks were recorded daily for each channel. Dew point The dew point was measured with a CoR Hygrometer which was also connected to the Sanborn recorder. This unit operated on the controlled resistance of a lithium chloride film. It has a dew point range of -20DC to +30DC with an accuracy of :t.5DC. The hygrometer was kept in the sun screen shelter along with the air temperature thermistor. Temperature readings taken from the LiCI film were used in a conversion chart to get the dew point value. PreclpltadoD A Belfort weighing recording rain gage was used to monitor precipitation at the station. A 7-day trace was examined once a week during the dry weather. but charts were removed after every storm with significant precipitation. Wind A circular-dial, three cup Belfort Anemometer was used to record total wind in miles per day. The anemometer was mounted on the center evapora- tion pan platform at the 2-foot level. The wind movement, recorded mechanically on two circular scales. was read once a day. A small, four cup anemometer and electronic counter were also installed initially but were removed after the Belfort calibration was verified. Empirical .Dpp.....loD resullll The evaporation station was operational and recording on August 19, 1974. Records were maintained until the night time temperatures dropped to freezing, which was up through October 25, 1974. A table of the recorded data is listed in Appendix B. Every three consecutive temperatlii~ measure- ments from the recorder chart were averaged together for one hourly value. The pan water temperature, air temperature, and dew point were 16