Engineering Wonders of the World
Volume III

62 ENGINEERING WONDERS OF THE WORLD. by the United States army. It has a pointed stem and stern ; a long car attached close to the gas-holder; elevating The Baldwin pjaneg the fore end, and Airship. vertical rudder at the rear of the car ; and a single tractor screw. On its official trials this airship made an in- dependent speed of nearly 20 miles an hour. DIAGRAM TO SHOW THE METHOD USED FOR SUS- PENDING THE CAR OF “ PARSEVAL II.” The cords pass round rollers which allow the car4;o retain its horizontal position when the balloon tilts. The list of the world’s airships cannot be made complete, as at the time of writing many dirigibles are in course of construction or on trial for all the great Powers. In Eng- land a huge rigid airship is being built at Barrow. The Germans have a dozen or more in hand. Russia, Japan, Italy, Belgium, Austria, Spain, and the United States are all busy. The Continental Tyre Company’s fabric is most commonly employed for the gas chambers of dirigibles. It is built up of four layers. Beginning on the outside, we Material used ^ave—(1) Layer of cotton cloth for Balloons. jmpregnated with yellow chro- mate of lead to keep out the actinic (blue to ultra-violet) rays of the sun, which do damage to rubber ; (2) layer of vulcanized rubber sheeting to retain the gas ; (3) layer of cotton cloth to reinforce that on the outside ; (4) thin layer of vulcanized rubber to protect the cotton against the chemical action of the hydrogen gas. In th© Gross airships this layer is dispensed with. The four-layer fabric weighs slightly under ten ounces per square yard. A strip one foot wide will boar a strain up to 9o0 lbs. before tearing. The two layers of cotton cloth are laid diagonally to one another, so that the warp of the one may resist ripping in the weft of the other, and localize injuries to the fabric. Nulli Secundus II., the very moderately successful British army airship, had a bag built up of many layers of gold-beater’s skin, a very tough and impermeable but also very expensive material. There is no denying the fact that, whereas the development of and interest in the flying machine have been due largely to what one may call the sporting instinct, the dirigible balloon is con- The Dirigible in Warfare. sidered primarily to be an instrument of war. The value of being able to see and give information of what the enemy is doing, without incurring great risks, is of such value to a military commander that in the next great war the dirigible balloon will certainly be very fully tested. In rough weather it will be of no more use than the ordinary spherical balloon ; but that fact will not prevent its being kept ready for ascent under favourable conditions. As for the danger from gun fire, this would be minimized by rising to great heights ; and one cannot imagine a dirigible being employed that was not capable of ascending 5,000 to 6,000 feet above the earth’s surface, if it had to be sent directly over the enemy’s position. Even a much less height would allow its passengers to make observations, while keeping out of range. In the grim business of war bold spirits would not be wanting to take heavy risks on the chance of winning through—to play the counterpart of the naval scout. For several years to come, however, the dirigible will be used for observation only, not for dropping explosives or incendiary substances. Possibly a dirigible may have to attack the air craft of the opposing forces, and to that end might be furnished with small guns ; but