Outside instruments were still located below the old windmill on Wickham Terrace, a stiff uphill walk from the office. They were read at 9 am and 3 pm daily, except Sundays when a 9 am check was made. Some of the instruments were protected in a white louvred box-like structure, called Stevenson Screen. It contained the dry and wet-bulb thermometers for recording the 24-hour extremes of temperature, and the thermograph and hydrograph which plotted temperature and humidity on time-graduated charts. Within the observation yard were also a rain-gauge and recording pluviograph, a wind vane and a sunshine recorder. There was also an evaporation tank which recorded the amount of moisture drawn up by the sun. Thermometers suspended on chains in metal cylinders down to six feet below ground level indicated earth temperatures. The observer also took note of the only air data available, namely his estimates of cloud type and amour height and movement.

All the data obtained was of use mainly for statistical purposes, establishing the climatic characteristics of the locality. Such observations were of only limited assistance to the forecaster. He relied most heavily on synoptic observations of atmospheric pressure derived from mercury barometers housed indoors at some reporting stations throughout the State. Barographs too, plotted the ever changing pressure on time charts.

Although weather processes take place in a three-dimensional atmosphere (as far up as about 15 kilometres) only surface observations were available in the early 1900s in the preparation of forecasts. These were plotted in code on a map of Australia, and analysed, particularly regarding atmospheric pressure, reduced to what it would be at mean sea level. From the position, intensity and movement of the highs and lows, deductions were made and forecasts issued.

Bureau of Meteorology