314 On the Construction of Kitchen 



but if, in consequence of their acquired lightness on 

 being heated, they rise upwards to the top of the air- 

 chamber, they will there come in contact with the 

 bottom of the shelf, which, instead of communicating 

 more heat to them, will deprive them of a part of that 

 which they bring with them from below. But circum- 

 stances are very different in the blowpipes of a roaster: 

 in them the particles of air acquire continually additional 

 heat from every part of the surface with which they come 

 into contact in their passage through the tube. 



From this view of the subject, we see how very essen- 

 tial it is that the shelf of a roasting-oven should be so 

 composed or constructed that heat may not readily find 

 its way through it ; and we see likewise how necessary 

 it is to manage the registers of blowpipes and of air- 

 chambers with proper care. 



CHAPTER VI. 



Of the Usefulness of small iron Ovens, and of the best 

 Methods of constructing them and managing them. 



Reasons why they have not succeeded in many Cases 

 wliere they have been tried. Ovens may be used for 

 otJter Processes of Cookery besides Baking. Curious 

 Results of some Attempts to boil Meat in an Oven. 



Explanation of these Appearances. Conjectures 

 respecting the Origin of some national Customs. 



IN the first part of this tenth Essay I recommended 

 small iron ovens for cottagers, and nests of small 

 ovens for the kitchens of large families ; and I have 



