80 GENERAL MANAGEMENT OF POULTRY. 



management. The Tomlinson incubator is shown in section in 

 Figs. 16 and 17. A is the case, enclosing packing shaded 

 black, and projecting at one side over the lamp D ; c the water 

 tank, also projecting over the lamp, and traversed by two 

 or more hot-air flues ; E is a door for cleaning the flues without 

 interfering with the machine ; F is the front of egg-drawer, 

 with the thermometer-scale showing outside \ G is the egg- 

 drawer, fitted with perforated zinc tray covered with flannel, 

 underneath which are evaporating-pans for holding wet sand ; 

 H H are openings in the bottoms of the machine, doubly 

 covered with perforated zinc, for admitting air to the drawer ; 



\ / 



Fig. 18. Tomlinson's Regulator. 



the air thence passes through small holes in the wooden 

 bottom of the drawer, and thence over the moist sand, passing 

 out through holes in the sides of the drawer into chambers h k, 

 communicating with a vertical flue at the back, surmounted by 

 the controlling regulator-valve L. The regulator itself is also 

 lettered L in Fig. 16; but the valve is so set as to allow 

 a certain minimum amount of ventilation at all times. 



The regulation of this machine depends upon the expansion 

 of air, and is shown in Fig. 18. The glass tube shown in the 

 figure is sealed at both ends, and has on the under side a cup- 

 shaped opening, which is closed by a diaphragm or membrane 

 of india-rubber tied tightly round its lip ; but before this 

 is done the temperature is brought to about 90 Fahr., and a 

 little water put w. the tube, which inns down to the cup and 



