VI 



CONTENTS 



This chapter on the 

 sun's gift of heat an- 

 swers the question, 

 " What makes it go?" 

 and deals with the most 

 common form of en- 

 ergy, heat. 



This chapter has to 

 do with air, the com- 

 monest thing in our 

 natural environment. 



CHAPTER IV. THE SUN'S GIFT OF HEAT 

 Potential and Kinetic Energy Forms of En- 

 ergy "Loss of Energy" Conservation of 

 Energy Some Effects of Heat Mass, Vol- 

 ume, Density, Weight Nature of Heat 

 Production of Heat Combustion Kindling 

 Temperature Saving Fuel Control of Fire 



Measurement of Temperature Measure- 

 ment of Heat Specific Heat Latent Heat 



Transference of Heat : Conduction, Con- 

 vection, Radiation Conserving Heat . 60 

 Expansion and contraction of bridge-spans, con- 

 crete sidewalks, table glassware, ice, water, 

 steam. Use of kindling. Tending a furnace fire. 

 Abating tbe smoke nuisance. Fire extinguishers. 

 Thermometers. Blankets and sheets as con- 

 ductors of heat. Heat insulation: revolving 

 doors, fireless cookers, thermos bottles, refriger- 

 ators, and snow. 



CHAPTER V. THE ATMOSPHERE AND ITS 

 SERVICE TO MAN 



Origin of the Atmosphere Composition of 

 Air Need of Air Moisture in the Air 

 Evaporation Boiling Effect of Heat on Air 

 Humidity Humidity and Comfort Hu- 

 midity and Health Weight of Air Expan- 

 sion of Air Ventilation Atmospheric Pres- 

 sure Measuring Atmospheric Pressure 

 Air Pressure Machines Air Pressure and 

 Heat Ice Manufacture and Cold Storage 

 The Barometer Determination of Height by 

 Air Pressure ...... 96 



Perspiration, fever, transpiration, humidity in 

 living-rooms and assemblies, humidifiers. Circu- 

 lation in a refrigerator, hot-air furnace. Use of 

 electric fan in summer and winter, home-made 

 ventilating devices. Lift-pumps. Vacuum clean- 

 ers, street-sweeping machines. Compressed air 

 to operate air-brakes, whistles, ventilating sys- 

 tems, force-pumps. Pressure cooker. Ice manu- 

 facture. Cold storage. 



