2 HEAT. 



Q. What are the four principal SOURCES of 

 heat ? 



A. 1. The Sun. 2. Electricity. 

 3. Chemical Action : and 4. Mechan- 

 ical Action. 



Q. What are the principal EFFECTS of heat ? 



A. Expansion, Liquefaction, Vapo- 

 rization, and Ignition. 



CHAPTER I. 



Q. What is the PRINCIPAL source of Heat ? 



A. The SUN. 



Q. Why do BURNING GLASSES set fire to 

 substances submitted to their power ? 



A. The rays of the sun, collected by 

 the Burning Glass, are all bent to one 

 point, called the "focus;" thus the heat 

 and light, (which should be diffused 

 over the whole glass,) being gathered 

 together into one point, are very greatly 

 increased. 



