1906.] 



Artificial Incubation. 



207 



with fourteen incubators of six different makes there are 

 differences in the individual machines which to some extent 

 may account for these variations, as, for instance, when one 

 class is both highest and lowest in the same months. Com- 

 parisons would be more correct if the same number of machines 

 of each class were recorded and only those used during the 

 entire year. Such a comparison would, however, need special 

 arrangements, and the object of these observations is to show 

 what can be done by working in the regular manner. No 

 doubt similar variations would be found if all the fourteen 

 incubators had been of one class and size. A careful exami- 

 nation of the records of each machine, which would be very 

 lengthy to give in detail, has not yielded any explanation of 

 the changes recorded. 



TABLE III— HIGHEST AND LOWEST PERCENTAGES FOR EACH 



MONTH. 



Month. 



Class of 

 Machine. 



Highest 

 Hatching 

 Percentages. 



Class of 

 Machine. 



Lowest 

 Hatching 

 Percentages 



Percentage of Hatching 

 in each Class of 

 Machine. 



1905. 

 April ... 

 May 

 June 



July ... 

 August ... 

 Sept. 

 Oct. 

 Nov. 



Dec. ... 











Tank. 



Hot Air. 



A 

 A 

 A 

 C 

 A 

 A 

 A 

 C 

 D 



88-1 



93- 87 



84- 94 

 87-3 

 87-87 



94- 59 

 87-23 



8o'43 



85- 71 



C 

 D 

 F 

 B 

 A 

 C 

 C 

 A 

 B 



59-57 

 65-88 

 34-78 

 44-82 

 47-22 

 77-14 

 59-67 

 71-43 

 75-0 



82-5 



81-72 



67-67 



64-18 



71-61 



88-32 



87-23 



71-43 



78-12 



75-62 



73-39 

 62-13 

 82-12 



55-44 

 77-14 



59-67 

 77-94 

 80-28 



1906. 

 Jan. 



Feb. ... 

 March ... 



A 

 D 



A 



90-9 



73-68 



87-18 



C 

 C 

 A 



67-3 

 56-0 

 46-66 



82-25 



64-6 



74-06 



71-18 

 66-79 

 73-57 



The monthly percentages of hatching results for tank (A, 

 B, and F), and hot-air (C, D, and E) incubators respectively 

 are also indicated in the above table, from which it will be seen 

 that in April, May, June, August, September, October, 1905, 

 January and March, 1906, the tank machines gave the highest 

 results ; and that in July, November, December, 1905, and 

 February, 1906, the hot-air machines were in advance. The 

 totals for the entire twelve months were : tank machines 

 (49 hatches) yielded 75-42 per cent. (2,013 chickens and duck- 



