Page:Journal of the American Society of Mechanical Engineers, Volume 33.pdf/678

Rh constant at No. 4 by continuous hand regulation at the fan inlet and continuous observations of thermometer No. 4. It was found possible in this way to prevent a variation of more than 0.05 deg. Results showed the temperature in the calorimeter with a wet bulb to be a little lower than a No. 3 when a dry bulb was used, owing to slightly imperfect saturation. This test, therefore, did not agree exactly with the results of experiment No. 2. It appeared to be possible, however, for the water on the wet bulb in experiment No.2 to be cooled to a lower temperature than that of adiabatic saturation, and it is necessary, therefore, to attribute this slight discrepancy to some source of error in the temperature of the air in experiment No. 3. Three explanations

are possible: (a) the air being thoroughly saturated before entering the tube of the calorimeter, its temperature would easily be increased with any slight adiati on due to imperfect insulation, especially since air delivery was greatly educe d by the resistance of the sponge; (b) at the time the readings were taken the outside was always beginning to get dry, due to the very long time required to bring the temperature of the calorimeter to a minimum, during which the cloth on the calorimeter would begin to dry and require moistening, resulting in a momentarily increase of temperature; (c) the possibility of some parts of the sponge becoming dry and conducting a slight amount of heat to the wet portions.

83The agreement of these tests, however, is quite sufficient to warrant fully the acceptance of the fundamental principles previously stated. It is also made evident that the reading of the wet-bulb thermometer properly protected from radiation as in experiment No. 2 is a most practicable and accurate method of determining the temperature of adiabatic saturation.