"Mmm. Yes," said Terry. He looked up. "Of course."
"It would be interesting to do it," said Tony, semicasually. Then he added hastily, "I've read somewhere that whales have been clocked at pretty high speeds. If we can find out how long its leap lasted, we could know how fast it was going."
Terry considered for a moment, and then got out the recorder. He played the tape for a moment, and skipped forward to later parts of the record until he came to the place where the unpleasant humming sound was loud, and finally reached the beginning of the rushing noise. That, in turn, had preceded the leap of the object photographed by the gun-cameras.
Terry glanced at his watch when the rushing started. He timed the period of ascent of the noise, while it grew louder and louder and became a booming sound, which was at its loudest the instant before it ceased. At that moment the mysterious object had leaped out of the sea. The splash of its re-entry came long seconds later.
Tony timed the leap. When the splash came he made his calculations absorbedly, while Terry switched off the recorder.
"It would take the same amount of time going up as it does coming down," said Tony, scribbling numbers. "Since we know how fast things fall, when we know how long they fall we can tell how fast they were traveling when they landed, and therefore when they leaped."
He multiplied and divided.
"Sixty miles an hour, roughly," he pronounced. "The whale was going sixty miles an hour straight up when it left the water! What can swim that fast?"
"That's your question," said Terry. "Here's one of mine. We heard it coming for five minutes ten seconds. How deep is the water where we were?"
"About forty-five hundred fathoms."