1846 



The Cornell Reading-Courses 



the isinglass has been broken, it should be replaced in order to prevent 

 fumes from getting into the egg chamber and in order to protect the flame 

 from drafts. The different parts of the heater are shown in Fig. 58. 



Felts and diaphragms 



One type of incubator has felts or burlap diaphragms in the bottom. 

 The operator should be sure that these are arranged properly before 

 undertaking to heat the incubator. To remove these felts or diaphragms 

 while eggs are being incubated, except as advised by the maker of the 

 incubator, would greatly lessen its hatching power in most cases. 



The thermometer 

 When an incubator is in operation, the thermometer should be kept 

 in the place designated by the manufacturer. No other make of ther- 



FiG. 59. — Several styles of thermometers, i and 2, Hanging; j and 4, contact; 5 



and 6, standing 



mometer than the one recommended by the manufacturer of the incubator 

 should be used. The most common types of thermometers are the contact, 

 the standing, and the hanging (Fig. 59). 



A new thermometer should be tested before it is used ; an old one should 

 be tested each season. In order to test a thermometer successfully, 

 a physician's clinical thermometer should be used as a standard, or any 

 standard thermometer that registers correctly between 100° and 110° F. 

 The two bulbs should be dipped at the same time into water registering 

 about 100° F. If the temperature recorded by the thermometer being 

 tested varies from the temperature recorded by the thermometer being 

 used as a standard, the amount of variation should be marked on the back 

 of the thermometer or on a tag tied to it, and allowance should be made 



