(Air-Shoes from 'An Adventure in Time' by Flagg)

“But how do the shoes work?” I asked Manuel.

“By means of broadcast power,” he replied. "The rod Is your pick-up instrument. I press this first red key—so. Do you hear the vibration? Power is now being received by radio. I press the white one. Peel the droning in your heels ? Power is being communicated to the air-shoes. Now if I were to press the blue button . . .”

“I would fly,” I said.

“Fly! No,” laughed Manuel. “Who said anything about flying? You would generate beneath your feet a thousand pounds of air-pressure to the square inch. This creates an air road on which you walk. You can ascend any height you please by merely stepping higher, as on stairs; to descend, notice the white button can not only be pressed but pushed forward in this notched groove—so. Each notch represents a decrease of one hundred pounds in air- pressure. There are ten notches, as you see. Thus by lessening the air resistance beneath your feet you can descend as easily as you rise. But come! Let me illustrate what I mean.”