124 ANNUAL REPORT. SMITHSONIAN INSTITUTION, 1908. 



weight as that used in the Patrie. It ditfers from the other in one 

 important feature — it is diagonal-thread; that is, the warp of the 

 outer hiyer of cotton cloth makes an angle of 45° with the warp of 

 the inner layer of cotton cloth. The result is to localize a rip or 

 tear in the material. A tear in the straight-thread material will 

 continue along the warp, or the weave, until it reaches a seam. 



Valves. — There are five in all, made of steel, about 14 inches in 

 diameter — one on the top connected to the car by a cord operated 

 by hand only; two near the rear underneath. These are automatic 

 but can be operated by hand from the car. Two ballonet valves 

 directly under the middle are automatic and are also operated from 

 the car by hand. The ballonet valves open automatically at a pres- 

 sure of two-thirds of an inch of water ; the gas valves open at a higher 

 pressure. 



Susjjension. — This airship has the " long " suspension ; that is, 

 the weight is distributed along practically the entire length of the 

 gas bag. A doubled band of heavy canvas is sewn with six rows of 

 stitches along the side of the gas bag. Hemp ropes running into 

 steel cables transmit most of the weight of the car to these two canvas 

 bands and thus to the gas bag. On both sides and below these first 

 bands are two more. Lines run from these to points half way be- 

 tween the gas bag and the car, then radiate from these points to dif- 

 ferent points of attachment on the car. This gives the triangular or 

 nondeformable system of suspension, which is necessary in order to 

 have the car and gas bag rigidly attached to each other. With this 

 " long " susj^ension, the Ville de Paris does not have the deformation 

 so noticeable in the gas bag of the Patrie. 



Car. — This is in the form of a trestle. It is built of wood, with 

 aluminum joints and 0.12-inch wire tension members. It is 115 

 feet long, nearly 7 feet high at the middle, and a little over 5^ feet 

 wide at the middle. It weighs 660 pounds and is considered un- 

 necessarily large and heavy. The engine and engineer are well to 

 the front ; the aeronaut with steering w^heels is about at the center 

 of gravity. 



Motor. — The motor is a TO to 75 horsepower " Argus," and is excep- 

 tionally heavy. , 



Propeller. — The propeller is placed at the front end of the car. 

 It thus has the advantage of working in undisturbed air ; the disad- 

 vantage is the long transmission and difficulty in attaching the pro- 

 peller rigidly. It has two blades and is 19.68 feet long with a pitch 

 of 26.24 feet. The blades are of cedar with a steel arm. The pro- 

 peller makes a maximum of 250 turns per minute when the engine is 

 making 900 revolutions. Its great diameter and width compensate 

 for its small speed. 



