AIRSHIPS AND AIRPLANES 



305 



ing to the right and left is controlled by a triple rudder placed 

 at the rear. The entire ship is about the size of an ocean 

 steamer, being 500 feet long and about 50 feet in diameter. 

 It weighs about ten tons and can carry six tons in addition 

 to fuel, cargo, and passengers. It can travel at a speed of 

 thirty miles an hour. Before the war a regular passenger 

 service was kept up in Germany ; and in seven months 183 

 journeys were made, carrying all together nearly 4000 pas- 

 sengers. These airships were capable of carrying twenty- 

 four persons and were fitted with a cabin and restaurant. 



FIG. 122. A Zeppelin airship over Berlin. 



Later forms of the Zeppelins have three cars and eight en- 

 gines, with a total of 820 horse power. These have attained 

 a speed of 75 miles an hour and can stay aloft for four days 

 and nights. 



History of airplanes. Leaving the subject of balloons 

 and airships, we now come to a study of airplanes, machines 

 that are heavier than air, and use no gas to hold them up. 

 For thousands of years men have tried to devise means of 

 flying. The first crude attempts were made to imitate the 

 shape and motion of a bird's wing. 



In 1886 Mr. Wenhane constructed a machine, which 

 contained a number of surfaces arranged in tiers one above 



