New Developments in Science 609 



The electric furnace uses resistance coils to heat water, which 

 is stored in a tank like a huge thermos bottle and released to the 

 radiators as needed. 



A thermostat is an automatic device for regulating the tem- 

 perature of a room or building. 



Dry ice, made by compressing and cooling carbon dioxide gas, 

 is more effective than water ice, and is taking its place for many 

 cooling purposes, especially in the shipment of perishable foods 

 or foods that must be kept very cold, such as ice cream. 



Air conditioning means supplying clean air that has exactly 

 the right temperature and humidity for human comfort. Success- 

 ful air-conditioning apparatus is now in use in theaters, homes, 

 offices, stores, restaurants, and trains. 



The gyroscope is a heavy wheel that tends to hold the same 

 position in which it started, and to resist any force applied to 

 change that position. 



The gyroscope is used in stabilizers for keeping ships and air- 

 planes on an even keel ; in the construction of the gyro-compass, 

 which is more reliable on modern ships than the magnetic com- 

 pass ; in automatic pilots which steer ships and airplanes auto- 

 matically; and in automatic track recorders, which detect and 

 record inequalities in railroad tracks. 



A body designed to pass through the air or water with only a 

 small amount of resistance is said to be streamlined. Today many 

 airplanes, automobiles, trains, and steamships are streamlined. 



FACT AND THOUGHT QUESTIONS 



1. What is the essential difference between an autogiro and an airplane? 

 In what ways is the autogiro an improvement over the airplane? 



2. What are infra-red rays? Give some of their uses. 



3. Describe the photoelectric cell and tell how it works. 



4. Name several uses of the photoelectric cell. 



5. Tell how the simpler form of talking motion pictures operates. 



6. How are sounds recorded on the sound strip of a talking motion pic- 

 ture film? How are they reproduced? 



7. What is telephotography? How is it done? 



8. How is the image of a person broadcast by a television sending set ? 



9. Tell how a television receiving set works. 



