the iron is readier to take in heat just as water can be more readily 

 poured into a tumbler than into a bottle. How shall we test this sup- 

 position ? Suppose the tumbler and the bottle were both full of water, 

 out of which could you pour the water the more readily? Out of the 

 tumbler, of course. Now, let us try the same thing mth heat. Put 

 the hammer into a hot oven for a few minutes and feel which is hotter, 

 the head or the handle. The iron is; and so we find that when the 

 hammer is cold the iron feels colder than the wood because it takes 

 in heat more readily, and when the hammer is hot the iron feels 

 hotter than the wood, because it gives out heat to the hand more 

 readily. You will thus see that touch is a poor way of finding how 

 hot a body is. How can we discover a better way? We must find 

 something else that heat does, and perhaps that will give us a better 

 way of measuring it. 



II. 



HEAT EXPANDS LIQUIDS. 



Fill a bottle with cold water just up to the bottom of the neck, and 

 put the bottle in a pan or pot of moderately warm water on the stove. 

 Watch how the ^^•ater rises in the neck as the water becomes warmer, 

 how it finally comes to the top and at last overflows. You thus see 

 that heat expands water, and if there had been any other liquid than 

 Avater in the bottle the result would have been similar, except that 

 the amount of exjiansion might not have been the same. We con- 

 clude, then, that heat expands liquids. 



HEAT EXPANDS .sOLlDS. 



Take a bolt, and a nut that is a neat fit and will just screw on the 

 bolt. Heat the scre^^■ of the bolt in the fire and then see if you can 

 screw the nut on. Probably you can not; certainly you can not if 

 they fitted closely enough when they were cold. But if you had heated 

 the nut up instead of the bolt you would have found that it went on 

 more readily than before. 



If the schot)] building is heated by steam or hot water, see if yoa 

 can find a ]iart of the pipe at least 2b or 30 feet long. You will notice 

 that at certain iilaees the pipe is supported on upright wooden strips. 

 Stick needles into these strips at two places 2."> or 30 feet apart so 

 that the head of each needle is above the pipe and very close to it. 

 Then make a mark just below the head of each needle with a knife. 

 If you have doiio this when the pipe is cold, wait until some time 

 when the pipe is hot and see if the knife-marks are still just below the 



