Still, I could have gotten away with it if I had stuck to predictions that could not mature before 2000 A.D. Take the two where I really flopped, #5 and #16. In both cases I named a specific year short of 2000 A.D. Had I not ignored Mr. de Camp's warning, I could look bland and murmur, "Wait and see. Don't be impatient," on all in which the prediction does not look as promising in 1980 as it did in 1950.

Had I heeded a wise man on 2 out of 191 could today, by sheer brass, claim to be batting a thousand.

I have made some successful predictions. One is

"The Crazy Years." (Take a look out your window. Or at your morning paper.) Another is the water bed. Some joker tried to patent the water bed to shut out competition, and discovered that he could not because it was in the public domain, having been described in detail in STRANGER IN A STRANGE LAND. It had been mentioned in stories of mine as far back as 1941 and several times after that, but not until STRANGER did the mechanics of a scene require describing how it worked.

It was not the first man to build water beds who tried to patent it. The first man in the field knew where it came from; he sent me one, free and freight prepaid, with a telegram naming his firm as the "Share - Water Bed Company." Q.E.D.

Our house has no place to set up a water bed. None. So that bed is still in storage a couple of hundred yards from our main house. I've owned a water bed from the time they first came on market - but have never slept in one.

I designed the water bed during years as a bed patient in the middle thirties: a pump to control water level, side supports to permit one to float rather than simply lying on a not - very - soft water - filled mattress, thermostatic control of temperature, safety interfaces to avoid all possibility of electrical shock, waterproof box to make a leak no more important than a leaky hot water bottle rather than a domestic disaster, calculation of floor loads (important!), internal rubber mattress, and lighting, reading, and eating arrangements - an attempt to design the perfect hospital bed by one who had spent too damned much time in hospital beds.

Nothing about it was eligible for patent - nothing new - unless a sharp patent lawyer could persuade the examiners that a working assemblage enabling a person to sleep on water involved that - how does the law describe it? - "flash of inspiration" transcending former art. But I never thought of trying; I simply wanted to build one - but at that time I could not have afforded a custom - made soapbox.

But I know exactly where I got the idea. In 1931, a few days after the radio - compass incident described in the afterword to SEARCHLIGHT, I was ordered to Fort Clayton, Canal Zone, to fire in Fleet Rifle & Pistol Matches. During that vacation - with - pay I often re turned from Panama City after taps, when all was quiet. There was a large swimming pool near the post gate used by the Navy and our camp was well separated from the Army regiment barracked there.

I would stop, strip naked, and have a swim - nonreg (no life guards) but no one around, and regulations are made to be broken.

Full moon occurred about the middle of Fleet Matches - and I am one of those oddies who cannot sink, even in fresh water (which this was). The water was blood warm, there was no noise louder than night jungle sounds, the Moon blazed overhead, and I would lie back with every muscle relaxed and stare at it - fall into it - wonder whether we would get there in my lifetime. Sometimes I dozed off.

Eventually I would climb out, wipe my feet dry with a hanky, pull on shoes, hang clothes over my arm, and walk to my tent in the dark. I don't recall ever meeting anyone but it couldn't matter - dark, all male, surrounded by armed sentries, and responsible myself only to a Marine Corps officer junior to me but my TDY boss as team captain - and he did not give a hoot what I did as long as I racked a high score on the range (and I did, largely because my coach was a small wiry Marine sergeant nicknamed "Deacon" - who reappears as survival teacher in TUNNEL IN THE SKY).

Some years later, bothered by bed sores and with every joint aching no matter what position I twisted into, I thought often of the Sybaritic comfort of floating in blood - warm water at night in Panama - and wished that it could be done for bed patients.. . and eventually figured out how to do it, all details, long before I was well enough to make working drawings.

But 1) I never expected one to be built; 2) never thought of them (except for myself) other than as hospital beds; 3) never expected them to be widely used by a fair percentage of the public; 4) and never dreamed that they would someday be advertised by motels for romantic - exotic - erotic weekends along with X - rated films on closed - circuit TV.

By stacking the cards, I'm about to follow the advice of both Bill Gresham and Sprague de Camp. First, I will paint a gloomy picture of what our future may be. Second, I'll offer a cheerful scenario of how wonderful it could be. I can afford to be specific as each scenario will deny everything said in the other one (de Camp), and I can risk great gloom in the first because I'll play you out with music at the end (Gresham).

GLOOM, WOE, AND DISASTER - There are increasing pathological trends in our culture that show us headed down the chute to self - destruction. These trends do not require that we be conquered - wait a bit and we will fall into the lap of whichever power cares to occupy us. I'll list some of these trends and illustrate (rather than prove) what I mean. But it would be tediously depressing to pile up convincing proof - I'm not running for office. I do have proof, on file right in this room. I started clipping and filing by categories on trends as early as 1930 and my "youngest" file was started in 1945.

Span of time is important; the 3 - legged stool of understanding is held up by history, languages, and mathematics. Equipped with these three you can learn anything you want to learn. But if you lack any one of them you are just another ignorant peasant with dung on your boots.

A few years ago I was visited by an astronomer, young and quite brilliant. He claimed to be a longtime reader of my fiction and his conversation proved it. I was telling him about a time I needed a synergistic orbit from Earth to a 24 - hour station; I told him what story it was in, he was familiar with the scene, mentioned having read the book in grammar school.

This orbit is similar in appearance to cometary interplanet transfer but is in fact a series of compromises in order to arrive in step with the space station; elapsed time is an unsmooth integral not to be found in Hudson's Manual but it can be solved by the methods used on Siacci empiricals for atmosphere ballistics: numerical integration.

I'm married to a woman who knows more math, history, and languages than I do. This should teach me humility (and sometimes does, for a few minutes). Her brain is a great help to me professionally. I was telling this young scientist how we obtained yards of butcher paper, then each of us worked three days, independently, solved the problem and checked each other - then the answer disappeared into one line of one paragraph (SPACE CADET) but the effort had been worthwhile as it controlled what I could do dramatically in that sequence.

Doctor Whoosis said, "But why didn't you just shove it through a computer?"

I blinked at him. Then said slowly, gently, "My dear boy - " (I don't usually call Ph.D.'s in hardcore sciences "My dear boy" - they impress me. But this was a special case.)

"My dear boy ... this was 1947."

It took him some seconds to get it, then he blushed.

Age is not an accomplishment and youth is no sin. This young man was (is) brilliant, skilled in mathematics, had picked German and Russian for his doctorate. At the time I met him he seemed to lack feeling for historical span ... but, if true, I suspect that it began to itch him and he made up that lack either formally or by reading. Come to think of it, much of my own knowledge of history derives not from history courses but from history of astronomy, of war and military art, and of mathematics, as my formal history study stopped with Alexander and resumed with Prince Henry the Navigator. But to understand the history of those three subjects, you must branch out into general history.