Robert Heinlein - The Number of the Beast

"Five klicks H-above-G, Captain."

"Thanks, Jake." The board showed dive rate-straight down!-of over seven hundred kilometers per hour, and increasing so fast that the units figure was an unreadable blur, and the tens place next to it was blinking one higher almost by the second.

Most carefully I eased her out of dive, and gently, slowly opened her wings part way for more lift as she slowed, while making a wide clockwise sweep to the east-slowed her dive, that is, not her speed through the air. When I had completed that sweep, and straightened out headed for that column of smoke on course west, I was making over eight hundred kilometers per hour in unpowered glide and still had almost a klick H-above-G I could turn into greater speed.

Not that I needed it- I had satisfied myself by eye of what I had been certain of by theory: an ornithopter is slow.

Jake said worriedly, "May I ask the Captain his plans?"

"I'm going to give Colonel Pistoisky something to remember us by! Gay Deceiver."

"Still aboard, Boss."

I kept my eye on the flappy birds still in the air while I let Gay fly herself. Those silly contraptions could not catch us but there was always a chance that a pilot might dodge the wrong way.

Most of them seemed anxious to be elsewhere: they were lumbering aside

right and left. I looked at the smoke-dead ahead-and saw what I had not noticed before: an ornithopter beyond the smoke.

Jake gasped but said nothing. We were on collision course closing at about 900 kms/hr, most of it ours. Suicide pilot? Idiot? Panicked and frozen?

I let him get within one klick of us, which brought us almost to the smoke and near the deck, about 200 meters H-above-G-and I yelped, "Scout!"

Yes, Deety is a careful programmer; the sky was black, we were ten klicks H-above-G, and so far as I could tell, the same barren hills under us that we had left five minutes earlier-and I was feeling cocky. My sole regret was that I would not hear Colonel Snarfsky try to explain to the Grand Duke the "ghost" craft now used by "British spies."

Did Russian nobility practice "honorable hara-kiri"? Perhaps the loadedpistol symbol? You know that one: The officer in disgrace returns to his quarters and finds that someone has thoughtfully loaded his pistol and placed it on his desk....hereby saving the regiment the scandal of a court.

I didn't want the bliffy dead but busted to buck private. With time to reflect on politeness and international protocol while he cleaned stables.'

I checked our heading, found that we were still pointed west. "Gay Deceiver, Scout!"

Black sky again, the same depressing landscape- "Copilot, is it worthwhile to tilt down for a better look? That either takes juice-not much but some- or it takes time to drop far enough to bite air and do it with elevons. We can't afford to waste either time or juice."

"Captain, I don't think this area is worth scouting."

"Careful of that participle; better say 'exploring."

"Captain, may I say something?"

"Deety, if you are speaking as Astrogator, you not only may but must."

"I could reprogram to put us lower if I knew what altitude was just high enough to let you use elevons. Conserve both time and juice, I mean."

"It seems to be about eight klicks H-above-G, usually. Hard to say since we don't have a sea-level."

"Shall I change angle to arrive at eight klicks H-above-G?"

"How long does it take us to fall two klicks when we arrive?"

She barely hesitated. "Thirty-two and a half seconds."

"Only half a minute? Seems longer."

"Three-two point six seconds, Captain, if this planet has the same surface gravity as Mars in our own universe-three-seven-six centimeters per second squared. I've been using it and haven't run into discrepancies. But I don't see how this planet holds so much atmosphere when Mars-our Mars-has so little."

"This universe may not have the same laws as ours. Ask your father. He's in charge of universes."

"Yes, sir. Shall I revise the program?"

"Deety, never monkey with a system that is working well enough-First Corollary of Murphy's Law. If it is an area as unattractive as this, we'll simply get out. If it has possibilities, half a minute isn't too long to wait, and the

additional height will give us a better idea of the whole area. Gay Deceiver, Scout!"

We all gasped. Thirty kilometers and those barren hills were gone; the ground was green and fairly level-and a river was in sight. Or a canal.

"Oh, boy! Copilot, don't let me waste juice-be firm with me. Deety, count seconds. Everybody eyeball his sector, report anything interesting."

Deety started chanting "... thirteen fourteen fifteen-" and each second felt like ten. I took my hands off the controls to keep from temptation. That was either a canal or a stream that had been straightened, revetted, and maintained for years, maybe eons. Professor Lowell had been right- right theory, wrong universe.

"Deety, how far is the horizon?"

"-seventeen-about two hundred fifty klicks-twenty-"

I placed my hands gently on the controls. "Hon, that's the first time you've ever used the word 'about' with reference to a number."

"-twenty-four-insufficient data!-twenty-six-"

"You can stop counting; I felt a.quiver." I put a soft nose-down pressure on the elevons and decided to leave her wings spread; we might want to stretch this one. "Insufficient data?"

"Zebadiah, it was changing steadily and you had me counting seconds. Horizon distance at ten klicks height above ground should be within one percent of two hundred and seventy kilometers. That assumes that this planet is a perfect sphere and that it is exactly like Mars in our universe-neither is true. It ignores refraction effects, tricky even at home-and unknown to me here. I treated it as geometry, length of tangent for an angle of four degrees thirty-seven minutes."

"Four and half degrees? Where in the world did you get that figure?"

"Oh! Sorry, dear, I skipped about six steps. On Earth one nautical mile is one minute of arc-check?"

"Yes. Subject to minor reservations. With a sextant, or in dead reckoning, or on a chart, a mile is a minute, a minute is a mile. Makes it simple. Otherwise we would be saying a minute is one thousand eight hundred fifty-three meters and the arithmetic would get hairy."

"One-eight-five-three point one-eight-seven-seven-oh-five plus," she corrected me. "Very hairy. Best not convert to MKS until the last step. But, Zebadiah, there is a simpler relation here. One minute of arc equals one kilometer, near enough not to matter. So I treated H-above-G, ten klicks, as a versine, applied the haversine rule and got four degrees thirty-seven minutes or two hundred seventy-seven kilometers to the theoretical horizon. You see?"

"I see everything but how you hide haversine tables in a jump suit. Me, I hide 'em in Gay... and make her do the work." Yes, I could nose her over now-easy does it, boy.

"Well, I didn't, exactly. I calculated it, but I did it the easy way: Naperian logarithms and angles in radians, then converted back to degrees to show the relationship to kilometers on the ground."

"That's 'the easy way'?"

"It is for me, sir!"

"If you're quivering your chin, stop it. I told you it was your luscious body, not your brain. Most idiots-savants are homely and can't do anything but their one trick. But you're an adequate cook, as well."

That got me a stony silence. I kept easing her nose down. "Time for binox, Jake."

"Aye aye, sir. Captain, I am required to advise you. With that last remark to the Astrogator you risked your life."

"Are you implying that Deety is an inadequate cook? Why, Jake!"

Hilda interrupted. "She's a gourmet cook!"

"I know she is, Sharpie... but I don't like to say it where Gay can hear- Gay can't cook. Nor has she Deety's other talent which 'tis death to hide. Jake, that's a settlement below."