Doctor Wood. Modern Wizard of the Laboratory: The Story of an American Small Boy Who Became the Most Daring and Original Experimental Physicist of Our Day-but Never Grew Up

It seems that a crackpot had, for some months, been pestering the air force of the Army and Navy to give a trial to his scheme of inflating an observation balloon with hot air instead of hydrogen, thus rendering it fireproof against attack by phosphorus incendiary bullets. His plan was to install a long iron pipe inside of the “sausage” along the bottom of the bag. This pipe was to supply gasoline vapor to huge Bunsen burners rising from the pipe, the flames heating the air with which the balloon had been filled. The Army and Navy said no over and over again, so the crackpot did what all discouraged crackpots do — he got some congressmen interested in his invention, and the congressmen said to the Army and Navy, as they always do, “This man’s invention must be tested. Army and Navy officers are old fogies, too conservative. Don’t appreciate genius. Our army must have it, or he’ll sell it to the enemy”, etc., etc. And the Army said, “O.K., have it your own way”, as the Army and Navy are apt to do when a congressional committee gets after them. But the air force was too busy with more important work to make the test, so they passed the buck to the Science and Research Division, saying, “Give the guy a break and test his invention”, and the officer commanding the division assigned the job to the Baltimore Experiment Station. I begged to be excused, saying that the idea was preposterous: the weight of the pipe, fuel, etc., could never be lifted by hot air, even senatorial hot air. I showed that the temperature would have to be so high that the fabric of the balloon would burn, but was told that the Bureau of Standards had already made preliminary experiments and had found that you could have a “temperature gradient”, i.e., very hot air in regions not too near the fabric. I was shown the apparatus. It was a box the size of a trunk lined with asbestos, filled with heating coils of wire and bristling with thermometers. I said, “No, No, and NO. You will have a convection current of hot air from the long gasoline burner rising in a sheet and breaking against the top of the bag, which will char the rubberized cloth before the buoyancy will be sufficient to even lift the balloon fabric alone, without the weight of the observer, iron pipe, gasoline tank, air compressor, and other paraphernalia”. It was useless, however, and Lieutenant Paul Mueller of the balloon section, a sergeant, and four privates, one of them Edison Pettitt, now a very distinguished astronomer at the Mount Wilson Observatory in California, were assigned to the Baltimore Experiment Station. They came over at once, and were very useful in connection with the construction of the various signaling devices during the months occupied in the erection of the balloon hangar. This was taking shape over the concrete floor, which had been laid on an unused part of the university campus, and a five-inch gas main brought in from Charles Street, distant some three or four hundred yards, with a special gasometer as big as a large wardrobe trunk. The burner tube was a three-inch iron pipe supported at the center and running the whole length of the standard observation balloon sent over by the air force.

Finally after months of labor the day came for the test. Mueller and I crawled inside of the big bag which had been pumped full of air and was resting on the floor. We ordered the gas turned on, and held our burning torches over the burners nearest the central vertical pipe of the long-armed T. As soon as these blazed up we ran rapidly, Mueller north and I south, lighting burner after burner as quickly as we could. When all were going we hurried back to the air trap which was the only means of escape. It was a fine sight. We were inside of a great cylindrical tent, partly luminous by transmitted daylight, which showed the geometrical patterns of the overlapping sections of the balloon fabric, and partly illuminated by the great blue gas flames, which were tipped with yellow and fluttered with a dull roar. I had my camera of course, and by the time I had set up the tripod, focused, and made the three-second exposure, it was getting pretty hot and very “close” inside the balloon. We crawled out through the air trap and drew several very long breaths. Our crew, augmented by a half dozen volunteers now, lifted the big bag from the ground to estimate its diminishing weight. It was not attached to the heavy burner, or to anything else, and just as it was showing an inclination to be self-supporting, I smelt a strong odor of burning rubber. Letting go of the supporting rope which ran along the side of the bag, I stepped back. A cloud of blue smoke was rising into the air all along the top of the balloon. “Shut off the gas. It’s all over — finished”. We had used possibly a dollar’s worth of gas, but the “test” had cost the government $30,000, we afterwards learned. The photograph, however, was a great success.

* * *