Otto-cycle engine; the Industrial Revolution waited on the steam engine; radiant power waited on a really cheap, plentiful power source. Since radiation of power is inherently wasteful, it was necessary to have power cheap and plentiful enough to waste.

The same war brought atomic energy. The physicists working for the United States Army, the United States of North America had its own army then, produced a superexplosive; the notebooks recording their tests contained, when properly correlated, everything necessary to produce almost any other sort of nuclear reaction, even the so-called

Solar Phoenix, the hydrogen-helium cycle, which is the source of the sun's power.

The reaction whereby copper is broken down into phosphorus, silicon29, and helium8, plus degenerating chain reactions, was one of the several cheap and convenient means developed for producing unlimited and practically free power.

Radiant power became economically feasible, and inevitable.

Of course Stevens included none of this in his explanation to Grimes.

Grimes was absent-mindedly aware of the whole dynamic process; he had seen radiant power grow up, just as his grandfather had seen the development of aviation. He had seen the great transmission lines removed from the sky -'mined' for their copper; he had seen the heavy cables being torn from the dug-up streets of Manhattan. He might even recall his first independent-unit radiotelephone with its somewhat disconcerting double dial. He had gotten a lawyer in Buenos Aires on it when attempting to reach his neighbourhood delicatessen.

For two weeks he made all his local calls by having them relayed back from South America before he discovered that it made a difference which dial he used first.

At that time Grimes had not yet succ.u.mbed to the new style in architecture. The London Plan did not appeal to him; he liked a house aboveground, where he could see it. When it became necessary to increase the floor s.p.a.ce in his offices, he finally gave in and went subsurface, not so much for the cheapness, convenience, and general all-around practicability of living in a tri-conditioned cave, but because he had already become a little worried about the possible consequences of radiation pouring through the human body. The fused-earth walls of his new residence were covered with lead; the roof of the cave had a double thickness. His hole in the ground was as near radiation- proof as he could make it.

'-the meat of the matter,' Stevens was saying, 'is that the delivery of power to transportation units has become erratic as the devil. Not enough yet to tie up traffic, but enough to be very disconcerting. There have been some nasty accidents; we can't keep hushing them up forever. I've got to do something about it.'

'Why?'

"Why?" Don't be silly. In the first place as traffic engineer for NAPA my bread and b.u.t.ter depends on it. In the second place the problem is upsetting in itself. A properly designed piece of mechanism ought to work - all the time, every time. These don't, and we can't find out why not.

Our staff mathematical physicists have about reached the babbling stage.'

Grimes shrugged. Stevens felt annoyed by the gesture.

'I don't think you appreciate the importance of this problem, Doc. Have you any idea of the amount of horsepower involved in transportation? Counting both private and commercial vehicles and common carriers,

North American Power-Air supplies more than half the energy used in this continent. We have to be right.

You can add to that our city-power affiliate. No trouble there, yet. But we don't dare think what a city-power breakdown would mean.'

'I'll give you a solution.'

'Yeah? Well, give.'

'Junk it. Go back to oil-powered and steam-powered vehicles. Get rid of these d.a.m.ned radiant-powered deathtraps.'

'Utterly impossible. You don't know what you're saying. It took more than fifteen years to make the change-over. Now we're geared to it. Gus, if NAPA closed up shop, half the population of the northwest seaboard would starve, to say nothing of the lake states and the Philly-Boston axis.'

'Hrrmph- Well, all I've got to say is that that might be better than the slow poisoning that is going on now.'

Stevens brushed it away impatiently. 'Look, Doc, nurse a bee in your bonnet if you like, but don't ask me to figure it into my calculations. n.o.body else sees any danger in radiant power.'

Grimes answered mildly. 'Point is, son, they aren't looking in the right place. Do you know what the high-jump record was last year?'

'I never listen to the sports news.'

'Might try it sometime. The record levelled off at seven foot two, 'bout twenty years back. Been dropping ever since. You might try graphing athletic records against radiation in the air - artificial radiation. Might find some results that would surprise you.'

'Shucks, everybody knows there has been a swing away from heavy sports. The sweat-and-muscles fad died out, that's all. We've simply advanced into a more intellectual culture.'

'Intellectual, hogwash! People quit playing tennis and such because they are tired all the time. Look at you.

You're a mess.'

'Don't needle me, Doc.'

'Sorry. But there has been a clear deterioration in the performance of the human animal. If we had decent records on such things I could prove it, but any physician who's worth his salt can see it, if he's got eyes in him and isn't wedded to a lot of fancy instruments. I can't prove what causes it, not yet, but I've a d.a.m.ned good hunch that it's caused by the stuff you peddle.'

'Impossible. There isn't a radiation put on the air that hasn't been tested very carefully in the bio labs.

We're neither fools nor knaves.

'Maybe you don't test 'em long enough. I'm not talking about a few hours, or a few weeks; I'm talking about the c.u.mulative effects of years of radiant frequencies pouring through the tissues.

What does that do?'

'Why, nothing-I believe.'

'You believe, but you don't know. n.o.body has ever tried to find out. F'rinstance - what effect does sunlight have on silicate gla.s.s? Ordinarily you would say "none", but you've seen desert gla.s.s?'

'That bluish-lavender stuff? Of course.'

'Yes. A bottle turns coloured in a few months in the Mojave Desert. But have you ever seen the windowpanes in the old houses on Beacon Hill?'

'I've never been on Beacon Hill.'

'OK, then I'll tell you. Same phenomena, only it takes a century more, in Boston. Now tell me, you savvy physics - could you measure the change taking place in those Beacon Hill windows?'

'Mm-rn-in - probably not.'

'But it's going on just the same. Has anyone ever tried to measure the changes produced in human tissue by thirty years of exposure to ultra short

-wave radiation?'

'No, but-'

'No "buts". I see an effect. I've made a wild guess at a cause. Maybe I'm wrong. But I've felt a lot more spry since I've taken to invariably wearing my lead overcoat whenever I go out.'

Stevens surrendered the argument. 'Maybe you're right,

Doc. I won't fuss with you. How about Waldo? Will you take me to him and help me handle him?'

'When do you want to go?'

'The sooner the better.'