SUCCESS IN POULTRY CULTURE 
kept well tested out, so that there will 
not be any, or but very few at least, dead 
or infertile eggs in the machine, the ther- 
mometer that lies on the eggs will not 
vary much more than the others. 
The thermometer that lies on the eggs 
can not very well be read without opening 
the door of the incubator, while the sus- 
pende’ thermometers can usually be read 
without opening the door. The opening 
of the door is, perhaps, a good thing for 
incubators that lack ventilation, but for 
those that have proper ventilation it 
might be a bad thing; so, on the whole, I 
think it better to follow, without devia- 
tion, the instructions of the manufacturer 
of the machine that you are using. 
The reason that it is so important 
that the thermometer needs to be just at 
the proper height is that the temperature 
increases so very rapidly as you go up 
towards the heating system of the ma- 
chine; therefore a very slight rise of the 
bulb of the thermometer above its proper 
place will cause it to register too high a 
temperature, and if it is very slightly too 
low it will not register high enough. 
Experience will help you much in han- 
48 
