In my previous communications to the Society on this subject some different forms of thermometer screens are described, and the results are given of a number of trials made with them during trying conditions of weather. The result of these tests showed that all the screens gave readings a little too high when there was much radiation, and that the thermometer in the fan apparatus also indicated too high a temperature, the readings of a fine-bulbed thermometer in a polished silver case being taken as our standard of temperature in these trials. The reasons are given for the thermometer in the draught screens indicating too high temperature, and the ineffectual attempts made at the time to check these errors are described.