INCUBATION 



421 



just back of a line joining the knife-edge bearings (m), which 

 rests on the two projections of the base casting (/) and which 

 acts as fulcrums. The damper arm (k) acts as a reverse lever, 

 and a little pull at g is transformed into a considerable raising 

 of the damper disk (l). The damper arm is balanced by a 

 counterbalance weight (j), and the damper will close of its 

 own accord unless restrained by a pull from the thermostat. 



For oil burning incubators, use good oil. Clean and fill the 

 lamp once daily, trimming the wick by scraping the charred 

 portion off with a knife or square-edged nail, or by cutting 

 the wick with scissors. The burners should be kept free from 



Fig. 158. — 1, The flame shaped as here illustrated will give the greatest 

 possible amount ot heat and may. be turned quite high without danger of 

 smoking. To secure it trim the wick as illustrated in 2. 2, The corners of 

 the wick must be rounded off as here indicated to get the ideal flame as shown 

 in 1. 3, If the corners of the lamp wick are not properly rounded off the 

 flame will be sharp-cornered, will smoke readily, form dangerous soot and the 

 lamp will supply comparatively little heat. 



dirt and thoroughly cleaned by boiling after each hatch. Turn 

 the eggs before caring for the lamp, so there will be no chance 

 of getting oil on the eggs and thus make possible the closing 

 of the shell's pores with oil. The flame is apt to increase in 

 size after lighting, so that it is advisable to return about half 

 an hour after tending to the lamp to see that the flame is all 

 right. 



The eggs are turned daily in the egg-trays during incubation, 

 except the last two days, when the incubator is not opened. 



Successful incubation depends on the faithful carrying out of 

 the four great principles — ^namely, proper ventilation, proper 



