142 Artificial Hatching of Chickens. [june, 



It is evident that we cannot expect the same average results 

 out of what may be termed the natural period of hatching, 

 viz., March to July, probably owing to the fact that the germs 

 within the eggs are more vigorous at that season. 



Much controversy has arisen as to the relative merits of tank 

 and hot-air machines, and it is interesting to study the com- 

 parative results in hatching, though probably the advocates of 

 each system may be surprised that these vary so little. 



Table III. — Hatching Results in Tank and Hot- Air Incubators. 





Tank Incubators. 



Hot- Air Incubators. 



Month. 



No. of 

 Hatches. 



Percentage of 

 Fertile Eggs 

 Hatched. 



No. of 

 Hatches. 



Percentage of 

 Fertile Eggs 

 Hatched. 



1903. 



April 



May .... 

 June ... 



July 



August 

 September 



7 

 7 



2 

 2 



2 



69-92 



69 74 

 76*62 

 8o-86 



79'3i 



5 

 3 

 2 



2 



73'33 



81- 14 

 80-18 



82- 05 

 72-38 



1904. 

 February 

 March... 



5 

 6 



71-1 



70-31 



* 3 

 5 



6476 

 66-15 



Year's Average 



3i 



70-89 



21 



68-95 



It is desirable to mention that in an incubator house such as 

 that in which these observations were made, the steadying 

 advantages of tanks in meeting great variations of temperature 

 are not so much in evidence as would be the case under less 

 favourable conditions, whilst, on the other hand, in the hot-air 

 machines there would be a lessened stress on the regulating 

 apparatus, due to the avoidance of extremes. It is important, 

 therefore, to keep that fact in mind, for the results might be 

 entirely different where the atmospheric influences were nearer 

 to the ordinary temperatures of both day and night. The night- 

 time is most dangerous in winter, and the daytime in summer. 



Taking the entire year, the tank machines have given the 

 higher averages, but on reference to Table III. it will be seen 

 .that in four months the hot-air incubators were in advance of 



