SCIENCE OF COMMON" THINGS. 145 



Familiar illustrations of the conduction of'heat. 



though both, therefore, are equally warm, the poker 

 seems to be the colder. 



030 Why does a stone or marble hearth feel to the feet colder than a car- 

 pet or hearth-rug ? 



Because stone and marble are good conductors ; but 

 woollen carpets and hearth-rugs are very ~bad conduc- 

 tors. 



i 03O Why does the stone hearth make our feet cold f 



As soon as the hearthstone has absorbed a portion 

 of heat from our feet, it instantly disposes of it, and 

 calls for ^ fresh supply ; till the hearthstone has be- 

 come of the same temperature as the foot placed upon it. 



031 Do not also the woollen carpet and hearth-rug conduct heat from 

 the human body f 



Yes ; but being very lad conductors, they convey 

 the heat away so slowly that the loss is scarcely per- 

 ceptible. 



33 Is the cold heartJistone in reality of the same temperature as the 

 warm carpet f 



Yes ; everything in the room, except our bodies, is 

 really of one temperature / but some tilings feel colde* 

 than others, because they are letter conductors. 



033 How long will the heartJistone feel cold to the feet resting on it ? 



Till iliefeet and the hearthstone are bot/i of the same, 

 temperature and then the sensation of cold in the 

 hearthstone will go off. 



034 Why would not the hearthstone feel cold, when it is of the samf 

 temperature as our feet ? 



Because the heat would no longer rush out of ou1 

 feet into the hearthstone, in order to produce equi' 

 librium. 



035 Why are cooking vessels of ten furnished with wooden handles? 



Because wood is not a good conductor like metal; 

 and therefore wooden handles prevent the heat of the 

 vessel from rushing into our hands to burn them. 



36 Why do persons use paper or woollen kettle-holders f 



Because paper and woollen are both very lad con- 

 ductors of heat, in consequence of which the heat of 



