RANKIN'S DUCK BOOK 



Figure 5. — Egg at End of 120 Hours. 



If your machine is in a warm, dry room, heated by a fire, 

 far more evaporating surface will be required than in a cool, 

 dry cellar, for the reason that water vaporizes just in propor- 

 tion to its heat; and as the circulating pipes upon which the 

 water-pans rest must necessarily be much warmer in a cold 

 room than in a warm one, of course more surface must be ex- 

 posed in a warm than in a cold one. The operator will always 

 have to use his judgment more or less in that. It may per- 

 plex the novice somewhat, but it is easily understood when one 

 becomes accustomed to it. 



As a rule, we introduced one moisture pan about the 18th 

 day for both duck's and hen's eggs. It makes some difference 

 whether a machine is run in a humid atmosphere near the sea- 



Figure 6. — Egg at End of 144 Hours. 

 [ 64 3 



