608 Our Surroundings 



ocean liners are being made more efficient. The Europa and 

 Bremen, with rounded bows and tapering sterns below the water 

 line, are faster and more economical to run than the older ocean 

 liners with their sharp, cutting bows and blunt sterns. 



SUMMARY 



The autogiro is supported in the air by a horizontal wheel, or 

 windmill, instead of by wings. It is safer than the airplane and 

 can take off and land within a smaller area. 



Infra-red rays are not visible to the eye, but will affect photo- 

 graphic negatives. They are used in taking pictures of distant 

 objects, and also in taking photographs in foggy weather and at 

 night. 



A photoelectric cell is a special glass bulb, useful in varying the 

 strength of an electric current to correspond to variations in the 

 intensity of a beam of light. 



Talking motion pictures are of two kinds. In one type of talk- 

 ing picture, the actors' voices are registered on phonograph 

 records. In the other type, both the sounds and the pictures are 

 recorded on the same strip of film. 



Telephotography is the sending of pictures by telegraph or 

 radio. 



Television, the latest development in radio, permits the listener 

 to see the broadcaster as well as hear him. 



One may now telephone to countries in Europe by means of a 

 combination telephone and radio system, which uses short radio 

 waves to bridge the gaps where there are no telephone wires. 



Radio is used in many ways to make flying safer. One of the 

 most important of these ways is the use of radio beacons, which 

 guide planes to them by means of continuous radio signals. 



One of the many uses of searchlights and floodlights is to 

 make night flying and landing safe. 



The oil burner uses fuel oil, which is vaporized, mixed with 

 air, and sprayed by force into the firebox of the furnace, where 

 it is burned. 



Gas is used as fuel in some heating systems. 



