seek these currents of air only by going up or down. Moreover, it may be very necessary to come down suddenly -if a heavy wind storm should come up and threaten the car with being swept over the ocean, or for other reasons. So the valve is a very important part of the outfit and must be carefully adjusted. It can be imagined that the aeronaut does this himself and does not leave it for hands other than his own. The valve is a ring of wood, with double doors opening into the balloon, held shut with elastic cords which pass to the top of a frame work, part of the valve. The cord operating the balloon valve passes from these doors, double, through the balloon and down the neck. ring of wood within the tube allows the neck of the balloon to be tied tightly about it. Next comes the adjusting of the valve, and this is a very important operation. The balloon, pure and simple, can not be controlled as to its direction, except by getting into a current of air which will bear it in the right direction. It can Before the valve can be adjusted, some means of walking on the balloon fabric must be provided. The balloon is made Little sacks of sand are placed all around to hold balloon down till inflation is completed. get the balloon inflated and then try to find the end of the valve cord in its interior. Besides the valve cord, there is the ripping cord. The balloon is split for part of its length from the valve down, and resewed with an insert piece. This is arranged so that a pull from its top will cause it to peel off inside, ripping the balloon and emptying it speedily of gas. This is, of course, an emergency way of opening the balloon, and not to be resorted to except in extreme need. The valves and cords adjusted-the valves greased for tightness and smooth working, the balloon is stretched out flat, to its full area. A large force of men is required for the task. The balloon in question, a racing balloon, and a of gas, its richness, temperature of the air, and other conditions. Spread out flat, the cordage netting, which covers the balloon, is next put in place, this being also stretched out smoothly, with the hole in the center of the net neatly fitting about the projecting air valve. Then everything being in readiness otherwise, numbers of small bags of sand are brought forward, and by means of the hooks with which their rope handles are provided, hooked to the netting about the balloon. Then the word is passed, and the gas turned on. The gas pumping engine-simply a turbine wheel revolved at speed by a small stationary engine-sets to work and fans in the gas at the rate of fifty thousand cubic feet per hour. As the balloon has nothing attracting a crowd more quickly than the sight of the monster gas bagnot "swaying gently to and fro," as the newspaper men have it, but standing still and tall, an unaccustomed sight, in the air. The impatient crowd about the enclosure sees the end of the long wait. But much still remains to be done. The car, prepared-of wicker work and lined with canvas, both for warmth and to provide pockets for instruments, observation books, camera, etc., must be hooked on. The leaders-the heavy cords which collect the ends of the cordage nettingare drawn into the car by main strength, several men to a leader, and hooked to the handles on the collector ring, to which the car is fastened. Then the sand bags are all lifted from the cordage netting-one at a time-and hung in bunches to the leaders. When they are all in place they are simultaneously pushed towards the center, the balloon going up in the air five or six feet as this is done, and at last it begins to appear in the shape in which it will go up. Then there comes the "balancing," a dainty operation, which is to leave the balloon with enough ascending power to make it go up, and still let it carry all the weight possible, in the form of the bags full of sand, ready to throw out when a greater height is wanted. The balancing is accomplished by putting too many sand bags in the car, and then having all hands let go. If the balloon stirs sluggishly, men lay hold and another bag is taken out. If the balloon seems inclined to go up with a rush, willing hands pull it down and another bag is added, until, when at last they let it go, the balloon sails slowly and majestically up and a little to one side, as the breeze catches it-and neither refuses to move nor bounds with a jump into the higher and rarer air. It has been said that the only control exercised over a balloon is as to its up or down motion. When it is desired to go higher, sand is thrown out in handfuls each lightening of the balloon, of course, sending it upwards to a point where its bulk is equal in weight to the bulk of air it displaces. It would seem then that it could continue to go up as long as there was sand to throw out, and, SAND BAGS ATTACHED TO THE LEADERS-HEAVY CORDS WHICH COLLECT THE ENDS OF THE NETTING. such is usually the case, but not always. For instance, an upward movement may send the balloon into a mist or a cloud, when the change in temperature immediately makes the balloon fall. Or it may drop or ascend from a cloud into bright sunshine, when the gas, very sensitive to temperature changes, expands and the balloon goes up. This expansion must be taken care of, so the neck of the balloon is left open. It is at the bottom, so that gas will not escape except by diffusion, which is a very slow process, yet if the gas expands from heat, it can be allowed to escape without rending the balloon or even straining it. This loss of gas must be cared for by sending sand ballast overboard. When all the ballast is gone, then the balloon can go no higher except by the caprice of wind and temperature. When it is desired to go lower the valve is opened and gas allowed to escape. Naturally the balloon drops. If it is to go up again, more sand is thrown out, and so on, seesawing, until the sand gives out or so much gas is lost that it is necessary to come down. Then the valve is again cautiously opened, the balloon gradually drifts nearer the earth, until the drag rope and anchor touch the ground. When the anchor catches, either the crowd which collects, even in rural districts, pulls the balloon down, or enough gas is let out to allow the whole to settle quietly down-and the flight is over. The racing balloon pictured herewith was made in Paris by Mallet, at a cost of about $2,000 and flown twice there. Its trial here, while in a measure designed simply as an experiment, and with the hope of further interesting war department officials, was really in the nature of a try-out-the balloon being designed for entry in the balloon races at St. Louis this year. The observations taken from the balloon were simply those usually kept-a recording barometer determining the air pressure and altitude, and a thermometer and a hygrometer the temperature and the humidity. This balloon has a net lifting capacity of one ton. |