^ECCALEBEION. 101 



Supposing the water heated in the boiler, 

 it rises by its specific levity through the 

 tube bj and more progressively through all 

 the tubes to 7i, when it passes down to the 

 bottom of the boiler. This circulating move- 

 ment, once established, continues as long as 

 the boiler is heated, because the tempera- 

 ture is never equal through all parts of the 

 apparatus ; and it is easy to conceive that 

 a perfect equality of temperature can never 

 exist, on account of the continual loss of 

 heat which escapes from the outsides of all 

 the tubes. It does not, however, become 

 greatly diminished, even after having ex- 

 pended a large portion of its caloric on the 

 outside of the box, in maintaining a gentle 

 heat in the chicken-box, e, adjoining. The 

 bent parts of the tubes outside of the box 

 are covered with woollen cloth. By means 

 of a regulator, a regular and constant tem- 

 perature is obtained. 



In practice, but one twentieth part of the 

 eggs which the apparatus is capable of hold- 

 ing is put in at first, and the remainder in 

 similar parts everv successive day. In this 



