MILITARY AERONAUTICS SQUIER. 123 



the material of which the gas bag is made without materialh" in- 

 creasing the weight. The rudder has been altered somewhat in form. 

 It was first pivoted on its front edge, but later on a vertical axis, 

 somewhat to the rear of this edge. With the increase in size has 

 come an increase in carrying capacit}', and consequently a greater 

 speed and more widely extended field of action. 



ViLLE DE Paris. 



This airship was constructed for Mr. Deutsch de la Meurthe, of 

 Paris, who has done a great deal to encourage aerial navigation. The 

 first Ville de Paris was built in 1902, on plans drawn by Tatin, a 

 French aeronautical engineer. It was not a success. Its successor 

 was built in 1906, on plans of Surcouf, an aeronautical engineer 

 and balloon builder. The gas bag was built at his works in Billan- 

 court, the mechanical part at the Voisin shop, also in Billancourt. 

 The plans are based on those of Colonel Renard's airship, the France, 

 built in 1884, and the Ville de Paris resembles the older airship in 

 many particulars. In September, 1907, Mr. Deutsch offered the use 

 of his airship to the French Government. The offer was accepted, 

 but delivery was not to be made except in case of war or emergency. 

 When the Patrie was lost in November, 1907, the military authorities 

 immediately took over the Deutsch airship. 



Gas hag. — The gas bag is 200 feet long for a maximum diameter 

 of 34| feet, giving a length of about 6 diameters, as in the France 

 and the Patrie; volume, 112,847 cubic feet; maximum diameter at 

 about three-eighths of the distance from the front, approximately, 

 as in t4ie Patrie. The middle section is cjdindrical, with conical 

 sections in front and rear. At the extreme rear is a cylindrical sec- 

 tion Avith eight smaller cylinders attached to it. The ballonet has 

 a volume of 21,192 cubic feet, or about one-fifth of the whole volume, 

 the same proportion found in the Patrie. The ballonet is divided 

 into three compartments from front to rear. The division walls 

 are of permeable cloth, and are not fastened to the bottom, so that 

 when the middle compartment fills with air and the ballonet rises 

 the division walls are lifted up from the bottom of the gas bag 

 and there is free communication between the three compartments, 

 ^he gas bag is made up of a series of strips perpendicular to a 

 meridian line. These strips run around the bag, their ends meeting 

 on the under meridian. This is known as the " brachistode " method 

 of cutting out the material, and has the advantage of bringing the 

 seams parallel to the line of greatest tension. They are, therefore, 

 more likely to remain tight and not allow the escape of gas. The 

 disadvantage lies in the fact that there is a loss of 33^ per cent of 

 material in cutting. The material was furnished by the Continental 

 Tire Companj^, and has approximately the same tensile strength and 



