“That was encouraging, but then no one could think of what to do. We still couldn’t see, and were not certain for some time whether or not the microphone was working. It was decided not to use the loudspeaker for a while. There was a faint humming sound being picked up whose intensity varied without apparent system, which we finally decided might be wind rather than electrical trouble, and once or twice some brief, harsh, quite indescribable noises which have not yet been identified; the best guess is that they may have been the voices of living creatures.
“We kept listening for a full rotation of the planet— nearly two of our days — and heard nothing else except a very faint buzzing, equally faint scratching sounds, and an irregular tapping that might or might not have been the footsteps of a hoofed creature on a hard surface. You may listen to the records we made, if you like, but you’d better have company around when you do. There’s something weird and unnerving about those noises out of nothing.
“I forgot to mention that the cargo port of the torpedo had been opened on landing, and microphones and weight detectors set to tell us if anything went in. Nothing did, however — a little surprising if there were small forms of wild life; the opening would have made a natural-looking shelter for them.
“Nothing even remotely suggestive of intelligence was heard during that rotation; and it was finally decided to use the loudspeaker. Someone worked out a schedule— starting at minimum power, repeating a tape for one rotation of the planet, then repeating with doubled output and so on until we reached the maximum which could be attained with that equipment. The program was followed, except that the boss was getting impatient and arranged to make the step-up each quarter rotation instead of the suggested time. Some humorist recorded a poem on the tape, and we started broadcasting.
“The first result was a complete cessation of the sounds we had tentatively associated with life forms. Presumably they were small animals, and were scared away by the noise. The wind, if that’s what it was, continued as expected. The first time we increased the noise, after a quarter rotation of the planet, we began to get a faint echo. That suggested that the sound was at least not being muffled very close to the speaker, and if any intelligent beings came within a considerable radius they would hear it.
“To make a long story short, we got a response after the fourth increase of power. We thought it was a distorted echo at first, but it got louder while our power remained constant, and finally we could tell that the sounds were different. They formed a tremendously complex noise pattern, and every one of us who heard them was sure from the beginning that they represented intelligent speech.
“Eventually we began to hear more footstep-sounds between the bursts of alien language, and we cut off our own broadcast. It became evident that the creature was close enough to detect the torpedo by other means than hearing, for the footsteps continued to approach. At first they were interrupted every few seconds by a loud call; but presently the thing must have actually reached the machine, for the sounds suggested that it was walking around at a nearly constant distance, and the calls were replaced by much less powerful but longer and more complex speech-noises. Probably the creatures can see much as we do, though the light is so much weaker on that planet.
“Presently the photocell inside the cargo compartment indicated that something had cut off much of the light One of the operators moved to close the door, and the boss knocked him clean out of the control room. He took the torpedo controls himself, and began attempting to imitate the voice sounds of the creature we couldn’t see. That produced results, all right! If noise means anything, the native got wildly excited for a minute or two; then he buckled down to producing apparently as wide a variety of sounds as his vocal apparatus would permit. Certainly we couldn’t imitate them all.
“That lasted for some time, with nobody making any real progress. Nobody had any way of telling what any of the other fellow’s noises meant, of course. It began to look as though we’d gone as far as we could, in learning about the planet, and that the knowledge was not going to do anyone any good.
“Then someone remembered the old swap-boxes. I don’t know whether you’ve heard of them; they were used, I guess, before our race ever left the home planet, when people who didn’t speak each other’s language wanted to trade. They are simply two trays, hinged together, each divided into a number of small compartments. One side is empty, while the compartments of the other are filled with various articles that are for sale. A glass lid covers each of the full compartments, and cannot be removed until something has been placed in the corresponding compartment of the other tray. It takes a pretty stupid savage not to get the idea in fairly short order.