DEVICES USED FOR HEATING 



129 



Van Ruskirk and Smith, The Science of Everyday Life, 

 Chap. 14 



Watkins and Bedell, General Science for Today, Chap. 21 



Webb and Beauchamp, Science by Observation and Experi- 

 ment, Unit 1 (part) 



Wood and Carpenter, Our Environment: How We Use and 

 Control It, Unit 2, Topic 7 



Special references 



Bolton, The Evolution of the Thermometer 



Taylor Instrument Company pamphlet, The Thermometer 



and Its Family Tree 

 Burns, Story of Great Inventions 

 Whitman, "How to Make a Thermometer," General Science 



Quarterly, May, 1920 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. A concept of heat as a form of energy. 



2. A knowledge of the construction and uses of Fah- 

 renheit and centigrade thermometers. 



3. Skill in making measurements with thermometers. 



4. A knowledge of how quantities of heat are meas- 

 ured. 



TEST OF MASTERY OF THE TOPIC 



In your notebook complete the statements, answer the 

 questions, and comply with the instructions. 



1. The temperature of a body is measured in ; the 



quantity of heat a body contains is measured in or . 



2. Heat is a form of . 



3. The boiling point of water on a centigrade thermom- 

 eter is ; its freezing point is at degrees. 



4. One degree on a centigrade thermometer is equal to 

 . degrees on a Fahrenheit thermometer. 



5. The boiling point of water on a Fahrenheit thermome- 

 ter is ; its freezing point on the same thermometer 



is , 



6. Two liquids commonly used in thermometers are 



and . 



7. The thermometer is most commonly used in sci- 

 entific work. 



8. To raise two kilograms of water 5 C. would require 

 . Calories. 



9. Write a paragraph on the importance of a knowledge 

 of heat values of various fuels. 



TOPIC 3. DEVICES USED FOR HEATING 



SUGGESTED PROBLEMS AND QUESTIONS 



1. How is heat transferred from place to place? 



2. What are some of the earlier methods of heat- 

 ing the home? 



3. How is a home heated by means of a hot-air 

 furnace ? 



What are the advantages and disadvantages 

 of this method of heating? 



4. How is a home heated by means of a hot- 

 water heating plant? 



What are the advantages and disadvantages 

 of a hot-water heating plant? 



5. How is a home heated by means of a steam 

 heating plant? 



6. What is air conditioning? 



SUGGESTIONS AND HELPS FOR STUDY 



1. Become thoroughly familiar with the problems 

 listed above before you begin your study. 



2. Get all the experience you can with the various 

 types of heating plants mentioned in this study. Ex- 

 amine them first hand if possible. 



3. Make diagrams of the heating systems men- 

 tioned in problems 3, 4, and 5. Label all the parts 

 neatly. 



4. The following words are new. Study them care- 

 fully and use them as often as possible in connection 

 with your work so that they will become a part of 

 your vocabulary. 



molecule the smallest bit of a substance that can exist 

 alone as such. 



ribrate to move to and fro. 



conduction movement of heat from molecule to mole- 

 cule. 



convection movement of heat by aid of currents. 



radiation movement of heat by ether waves without 

 the aid of matter. 



EXPERIMENTS OR DEMONSTRATIONS WHICH WILL 

 HELP ANSWER THE PROBLEM QUESTIONS' 



Experiment 89. How is heat radiated from a hot 

 body? 



Fill a shiny tin can with boiling water. Bring the palm 

 of your hand toward the sides of the can and note the 

 effects. Repeat the process from all sides and the bottom of 

 the can. Place some cardboard around the can and repeat 

 the observations. If you have hot-water or steam radia- 

 tors in your home, see whether heat is sent off in all direc- 

 tions from one of them. Does the can send off heat in all 

 directions? What is this method of heat transference called? 



Experiment 90. How does heat travel by conduction? 



Secure rods several inches long made of different metals. 

 Mount them on a board as shown in Figure 201. Put a 

 small piece of wax on the far end of each metal rod. Hold 

 the other ends of the rods in a flame and note the order in 

 which the pieces of wax melt. How does heat get from one 

 end of a metal rod to the other end? List the metals tested 

 in the order of their ability to conduct heat. Define conduc- 

 tion. 



1 See workbook, p. 45. 



