AIR AND WATER AS SERVANTS OF MAN 109 



ing in France, and Count von Zeppelin in Germany. Santos- 

 Dumont made the flight from outside of Paris over the city, 

 going around the Eiffel Tower. Zeppelin's dirigible was built 

 on a somewhat different plan from that of the Frenchman's. 

 In the German dirigible a rigid framework of light metal con- 

 struction contained the numerous gas bags. The car and the 

 motors were attached to this rigid framework. In the French 

 balloons the gas bags were held in a net to which, below the 

 balloon, there was attached the car for the aeronaut and engine. 

 Later a long metal beam that hung below the gas bags held the 

 car, thus making a semi-rigid balloon. The shape of the balloon 

 was maintained by keeping the gas bags well inflated. These two 

 types of dirigibles, rigid and non-rigid, are still maintained and, 

 as is well known now, the dirigible was greatly developed during 

 the war, although it did not accomplish what was anticipated, 

 especially by Zeppelin, it would do in offensive warfare. How- 

 ever, the dirigible is now driven by sufficiently powerful engines 

 to maintain headway even against a stiff wind. Such dirigibles 

 have made long flights. In 1920, a British dirigible with both 

 British and American men on board crossed the Atlantic from 

 Ireland to America and returned. In 1923 the Zeppelin L-72, 

 rechristened the "Dixmunde" by the French, its new owners, made 

 a flight of 4,500 miles in a non-stop flight of 118 hours. There 

 is keen competition between the dirigible and the aeroplane to 

 see which wfll be more serviceable in the transportation of goods 

 and passengers, with every prospect that both will serve, each 

 in its particular field, in solving some of the difficult problems of 

 transportation (Fig. 46). 



It is an easy matter for the child to repeat some of the experi- 

 ments that mark the discovery of the principles underlying the 

 operation of the balloon. He may readily make the hot-air 

 balloon, and directions for this are given in the Field and Labora- 

 tory Guide in Physical Nature-Study, page 49. He may make 

 hydrogen gas and inflate soap bubbles as directed in the same 

 book, page 54, and it is well for the child to go through such 



