MILITARY AERONAUTICS SQUIER. 119 



nately. On reaching the ground from the height of 1 mile the air 

 would be at the middle of the lower part of the gas bag and would 

 not entirely fill the ballonet. To prevent the air from rolling from 

 one end to the other when the airship pitches, thus producing insta- 

 bility, the ballonet w^as divided into three compartments by imper- 

 meable cloth jDartitions. Nimierous small holes were pierced in these 

 partitions through which the air finally reached the two end com- 

 partments. 



In Sei^tember, 1907, the Patrie was enlarged by 17,660 cubic feet 

 by the addition of a cylindrical section at the maximum diameter, in- 

 creasing the length but not the maximum diameter. 



The gas bag is cut in panels; the material is a rubber cloth made 

 by the Continental Tire Company at Hanover, Germany. It consists 

 of four layers, arranged as follows: 



Weight, ounces, 

 per square yard. 



Outer layer of cottou cloth covered with lead chromate 2.5 



Layer of vulcanized rubber 2.5 



Layer of cottou cloth 2.5 



Inuer layer of vulcanized rubber 2. 21 



Total weight 9.71 



A strip of this cloth 1 foot wide tears at a tension of about 934 

 pounds. A pressure of about one inch of water can be maintained in 

 the gas bag without clanger. The lead chromate on the outside is to 

 prevent the entrance of the actinic rays of the sun, which would cause 

 the rubber to deteriorate. The heavy layer of rubber is to prevent the 

 leaking of the gas. The inner layer of rubber is merely to prevent 

 deterioration of the cloth by impurities in the gas. This material has 

 the warp of the two layers of cotton cloth running in the same direc- 

 tion and is called straight thread. The material in the ballonet 

 weighs only about 7f ounces per square yard, and has a strength of 

 about 336 pounds per running foot. When the Patrie was enlarged, 

 in September, 1907, the specifications for the material allowed a maxi- 

 mum weight of 10 ounces per square yard, a minimum strength of 

 907 pounds per running foot, and a loss of 5.1 cubic inches of hydro- 

 gen per square yard in twenty-four hours at a pressure of 1.18 inches 

 of water. Bands of cloth are i^asted over the seams inside and out 

 with a solution of rubber to prevent leaking through the stitches. 



Suspension. — One of the characteristics of the Patrie is the " short " 

 suspension. The weight of the car is distributed over only about 70 

 feet of the length of the gas bag. To do this, an elliptical shaped 

 frame of nickel steel tubes is attached to the bottom of the gas bag; 

 bteel cables run from this down to the car. A small hemp net is 

 attached to the gas bag by means of short wooden cross pieces or 

 toggles, which are let into holes in a strong canvas band which is 

 88292— SM 1908 9 



