"I am afraid we can't accommodate you there," went on the head of the military school. "We are installing a wireless outfit, but it is not yet completed," the colonel said. "Oh, we carry our own!" was the unexpected retort. "Lieutenant Larson, if you and Lieutenant McBride will get the balloon ready, Captain Wakefield and myself will work out the cipher dispatch, and send it. "We use a code in our wireless," he went on to explain, "and it takes a few minutes to make up the message." "But I heard you speak of a balloon," said Colonel Masterly. "I don't see how you carry one on your machine." "Here it is," was the answer, and a deflated rubberized silk bag was produced from a locker back of the pilot's seat. "This is the latest idea in airship wireless," went on Captain Grantly, as he directed the lieutenants to get out the rest of the apparatus. "We carry with us a deflated balloon, which will contain about two hundred cubic yards of lifting gas. The gas itself, greatly compressed, is in this cylinder. There's enough for several chargings. "We fill the balloon, and attach to it our aerial wires. The balloon takes them up about four hundred feet--the wires weigh about twenty pounds, I might say. Then we carry a light sending instrument. It has a considerable range, though we can receive messages from a much greater distance than we can send, as our force for a sending current is limited." As he was talking the others were working, and the cadets looked on interestedly. The drill had been abandoned, and officers and students crowded up near the army aviators to see what was going on. With a sharp hiss the compressed gas rushed from the containing cylinder into the deflated balloon. The silken sides puffed out, losing their wrinkles. The balloon gradually assumed larger proportions. "Ready with the wires?" asked Captain Grantly. "All ready, sir," replied Lieutenant Larson. Dick now heard him speak for the first time, and did not like his voice. There are some persons who make a bad impression on you at the first meeting. Often this may he unjustified, but Dick's first impressions were seldom wrong. The wires, forming the wireless aerial, were carried up on two light spreaders, hanging down from a network that went over the balloon bag. From the aerials depended the wires that were attached to the receiving and sending apparatus. These wires were on a reel, and would he uncoiled as the balloon arose. The earth-end would be attached to the telephone receivers and to the apparatus, consisting of a spark-gap wheel and other instruments designed to send into space the electrical impulses that could be broken up into dots, dashes and spaces, spelling out words according to the Morse or Continental code--whichever was used. Captain Grantly looked over everything. His assistants signified that every connection was made.