Mayhew 1952 Mallard E 28 Experimental Univ. of Calif campus, Davis, Yolo Co., Calif. Feb. 29 The incubator has been set up to receive the mallard eggs that will be used in the humidity experiments. The incubator is a room 10 ft. x 9 1/2 ft. x 5 ft. that is heated by two electric heaters. In the room have been placed 4 plywood boxes that are 24 in. x 30 in. x 10 in. In each box is a tray with a wire bottom on which the eggs will be placed. Beneath the egg tray there is a metal tray that will contain the solution that maintains the relative humidity at a constant figure. These metal pans are 10 1/2 in. x 20 1/2 in. x 2 1/2 in. The room has the air circulated by means of a Westinghouse electric fan, style 516860-A, 100/120 volts, which is placed on the top shelf at the back of the incubator. The solutions used to maintain the humidities in the boxes & in the main room, which will also have a series of eggs, are: Box No. chemical *Relative Humidity main room NaCl 40% 1 NaCl 60% 2 KCl 70% 3 K2SO4 80% 4 2 pans of H2O 90% * This is the humidity before any eggs have been added. The humidity is checked by a Serdex hygrometer, model 201, & the temperature is measured by an HB laboratory Centigrade thermometer