342 ARTIFICIAL INCUBATION 



sirability of retarding evaporation in artificial incubation by in- 

 creasing the humidity of the air in the egg chamber, yet at the same 

 time permitting free ventilation. 



Experiments have been conducted involving one thousand 

 eggs set in eight machines, four with low and four with high 

 humidity, the average in the dry machines being 56 degrees, and 

 in the wet 68 degrees. The results showed that increased moisture 

 was desirable, and that there was much less loss in weight during 

 the incubating period. The average loss of weight for the wet 

 machines was 0.145 pound, and for the dry 0.23 pound, being nearly 

 double in the case of the dry machines. 



This same experiment also proved that increasing the moisture 

 within certain limits produced the following results: (1) It in- 

 creased the percentage of hatch, which was 62.0 per cent for the 

 dry and 69.6 per cent for the wet. (2) The resulting chicks 

 weighed much more at hatching time and were more vigorous, being 

 0.079 for the dry and 0.081 for the wet, there being five cripples 

 in the dry machines against one in the wet. (3) Produced greater 

 uniformity in the hatch, both from the standpoint of lapse of 

 time from pipping to complete hatching, as well as uniformity in 

 the chicks themselves. (4) The chicks from the moisture machines 

 were much more successfully brooded, the percentage being 52.3 

 for the dry against 89.5 for the wet. 



The retardation of evaporation is an important matter. The 

 extent to which it should be carried depends on atmospheric con- 

 ditions surrounding the egg and in the incubator room. Evapora- 

 tion may be checked by increasing the humidity in any of the 

 following ways : By frequent sprinkling of the floor and walls with 

 water; by placing under the egg trays moisture pans, usually filled 

 with sand which is kept wet; by putting a sponge or other material 

 saturated with water in the machine; by sprinkling the eggs at 

 frequent intervals with warm water; or by limiting the ventilation 

 by partially closing the ventilators. 



As a matter of fact, it is doubtful whether the humidity can 

 be kept too high. Humidity is ascertained by an instrument 

 called a hygrometer. The degree of moisture is computed by 

 comparing the readings from two thermometers, the bulb of one 

 being wrapped in a moist wick or cloth, while the other is dry. 

 The lower reading of the wet bulb is due to evaporation, hence 

 the difference between the two readings. The amount of evapora- 

 tion depends upon the humidity in the air. It is impossible to 



