The Black Cloud

Californian Scene

It is necessary now to describe the consternation that Kingsley’s cablegram produced in Pasadena. A meeting was held in Herrick’s office the morning after his return from Washington. Marlowe, Weichart, and Barnett were there. Herrick explained the importance of arriving quickly at a balanced view of the effects that the arrival of the Black Cloud would have.

“The position we’ve arrived at is this: our observations show that the cloud will take about eighteen months to reach us, or at any rate this seems rather likely. Now, what can we say about the cloud itself? Will there be any significant absorption of the Sun’s radiation when it comes between us and the Sun?”

“That’s very difficult to say without more information,” said Marlowe, puffing smoke. “At the moment we don’t know whether the cloud is just a tiny fellow quite close to us or whether it’s a biggish cloud farther away. And we’ve got no idea at all of the density of the material inside it.”

“If we could get the velocity of the cloud, then we should know how big it is and how far away,” remarked Weichart.

“Yes, I’ve been thinking about that,” went on Marlowe. “The Australian radio boys could get the information for us. It’s very likely that the cloud consists mainly of hydrogen, and it should be possible to get a Doppler shift on the 21 cm line.”

“That’s a very good point,” said Barnett. “The obvious man is Leicester in Sydney. We ought to get a cable off to him right away.”

“I don’t think that’s quite our job, Bill,” Herrick explained. “Let’s stick to what we can do ourselves. When we’ve sent in our report, it’ll be Washington’s job to contact the Australians about radio measurements.”

“But surely we ought to make a recommendation about getting Leicester’s group on to the problem?”

“Certainly we can do that, and I think we ought to. What I meant was that we ought not to initiate action of this sort. The whole business is likely to have serious political implications, and I feel that we ought to keep away from such things.”

“Right enough,” broke in Marlowe; ‘politics is the last thing I want to get involved in. But obviously we need the radio boys to get the velocity. The mass of the cloud is more difficult. As far as I can see the best way, perhaps the only way, would be from planetary perturbations.”

“That’s pretty archaic stuff, isn’t it?’ asked Barnett. “Who do it? The British, I suppose.”

“Yes, h’m,” murmured Herrick, “perhaps we’d better not emphasize that aspect of the matter. But the Astronomer Royal probably would be the best person to approach. I’ll make a point of it in the report, which I ought to start on as soon as possible. I think we’re agreed on the main points. Does anyone want to bring up anything further?”

“No, we’ve gone over the ground pretty thoroughly, as far as we can go, that’s to say,” answered Marlowe. “I think I’ll be getting back to one or two jobs that I’ve rather neglected during the last few days. I expect you’ll want to get that report finished. Glad I don’t have to write it.”

And so they filed out of Herrick’s office, leaving him to get down to his writing, which he did forthwith. Barnett and Weichart drove back to Caltech. Marlowe went to his own office. But he found it impossible to work, so he strolled along to the library where there were several of his colleagues. A lively conversation of the colour-magnitude diagram of the stars of the galactic nucleus contrived to pass the time until it was generally agreed that the lunch hour had arrived.

When Marlowe returned from lunch the Secretary sought him out. “Cablegram for you, Dr Marlowe.”

The words on the piece of paper seemed to swell to a gigantic size:

With a startled cry Marlowe raced along to Herrick’s office, and burst in without the formality of a knock.

“I’ve got it here,” he shouted. “All the things we wanted to know.”

Herrick studied the cablegram. Then he smiled somewhat wryly and said:

“This alters things quite a bit. It looks as though we shall have to consult with Kingsley and the Astronomer Royal.”

Marlowe was still excited.

“It’s easy to diagnose the situation. The Astronomer Royal has supplied observational material on the planetary motions and Kingsley has done the calculations. If I know those two fellows there isn’t much chance of a mistake there.”

“Well, it’s easy enough to do a quick check. If the object is 21.3 astronomical units distant and it’s moving towards us at seventy kilometres per second, then we can soon work out how long it should take to reach us, and we can compare the answer with Weichart’s estimate of about eighteen months.”

“Right you are,” said Marlowe. He then jotted the following remarks and figures on a sheet of paper:

“Perfect agreement,” exclaimed Marlowe. “And what’s more, the position they give is almost dead on our position. It all fits together.”

“This makes my report a much more difficult matter,” Herrick said with a frown. “It really should be written in consultation with the Astronomer Royal. I think we ought to get both him and Kingsley over here as soon as possible.”

“Absolutely right,” agreed Marlowe. “Get the Secretary on to it right away. It should be possible to get ’em over in about thirty-six hours, the morning after tomorrow. Better still, let your friends in Washington make the arrangements. And about the report, wouldn’t it be a good idea to write it in three parts? Part one could deal with our discoveries here at the Observatory. Part two would be contributed by Kingsley and the Astronomer Royal. And part three would be an account of our conclusions, especially the conclusions we reach when the British get here.”

“There’s a great deal in what you say, Geoff. I can get part one finished by the time our friends arrive. We can leave part two to them, and lastly we can thrash out our conclusions.”

“Excellent. I reckon you’ll probably get through by tomorrow. How about bringing Alison over for dinner tomorrow night?”

“I’d be glad to, delighted to, if I can get through by tomorrow afternoon. Can I leave it until then?”

“Sure, that’s fine. Just let me know tomorrow,” said Marlowe getting up.

As Marlowe was leaving, Herrick said:

“It’s pretty serious, isn’t it?”

“It certainly is. I had a sort of premonition when I first saw Knut Jensen’s pictures. I didn’t realize how bad it was until this cable arrived. The density works out in the region of 10–9 to 10–10gm. per cm3. That means it’ll block out the Sun’s light entirely.”

Kingsley and the Astronomer Royal arrived in Los Angeles early on the morning of 20 January. Marlowe was waiting to meet them at the airport. After a quick breakfast in a drug store they hit the freeway system to Pasadena.

“Goodness me, what a difference from Cambridge,” grunted Kingsley. “Sixty miles an hour instead of fifteen, blue skies instead of endless rain and drizzle, temperature in the sixties even as early in the day as this.”

He was very weary after the long flight, first across the Atlantic, then a few hours’ waiting in New York — too short to be able to do anything interesting, yet long enough to be tiresome, the epitome of air travel, and lastly the trip across the U.S.A. during the night. Still it was a great deal better than a year at sea getting round the Horn, which is what men had to do a century ago. He would have liked a long sleep, but if the Astronomer Royal was willing to go straight to the Observatory, he supposed he ought to go along too.

After Kingsley and the Astronomer Royal had been introduced to those members of the Observatory that they had not previously met, and after greetings with old friends, the meeting started in the library. With the addition of the British visitors it was the same company that had met to discuss Jensen’s discovery the previous week.

Marlowe gave a succinct account of this discovery, of his own observations, and of Weichart’s argument and startling conclusion.

“And so you see,” he concluded, “why we were so interested to receive your cablegram.”

“We do indeed,” answered the Astronomer Royal. “These photographs are most remarkable. You give the position of the centre of the cloud as Right Ascension 5 hours 49 minutes, Declination minus 30 degrees 16 minutes. That seems to be in excellent agreement with Kingsley’s calculations.”

“Now would you two care to give us a short account of your investigations?’ said Herrick. “Perhaps the Astronomer Royal could tell us about the observational side and then Dr Kingsley could say a little about his calculations.”

The Astronomer Royal gave a description of the displacements that had been discovered in the positions of the planets, particularly of the outer planets. He discussed how the observations had been carefully checked to make sure that they contained no errors. He did not fail to give credit to the work of Mr George Green.

“Heavens, he’s at it again,” thought Kingsley.

The rest of the company heard the Astronomer Royal out with interest, however.

“And so,” he concluded, “I’ll hand over to Dr Kingsley, and let him outline the basis of his calculations.”

“There is not a great deal to be said,” began Kingsley. “Granting the accuracy of the observations that the Astronomer Royal has just told us about — and I must admit to having been somewhat reluctant at first to concede this — it was clear that the planets were being disturbed by the gravitational influence of some body, or material, intruding into the solar system. The problem was to use the observed disturbances to calculate the position, mass, and velocity of the intruding material.”

“Did you work on the basis that the material acted as a point mass?’ asked Weichart.

“Yes, that seemed to be the best thing to do, at any rate to begin with. The Astronomer Royal did mention the possibility of an extended cloud. But I must confess that psychologically I’ve been thinking in terms of a condensed body of comparatively small size. I’ve only just begun to assimilate the cloud idea, now that I’ve seen these photographs.”

“How far do you think your wrong assumption affected the calculations?’ Kingsley was asked.

“Hardly at all. So far as producing planetary disturbances is concerned, the difference between your cloud and a much more condensed body would be quite small. Perhaps the slight differences between my results and your observations arise from this cause.”

“Yes, that’s quite clear,” broke in Marlowe amid aniseed smoke. “How much information did you need to get your results? Did you use the disturbances of all the planets?”

“One planet was enough. I used the observations of Saturn to make the calculations about the Cloud — if I may call it that. Then having determined the position, mass, etc., of the Cloud, I inverted the calculation for the other planets and so worked out what the disturbances of Jupiter, Mars, Uranus, and Neptune ought to be.”

“Then you could compare your results with the observations?”

“Exactly so. The comparison is given in these tables that I’ve got here. I’ll hand them round. You can see that the agreement is pretty good. That’s why we felt reasonably confident about our deductions, and why we felt justified in sending our cable.”

“Now I’d like just to know how your estimates compare with mine,” asked Weichart. “It seemed to me that the Cloud would take about eighteen months to reach the Earth. What answer do you get?”

“I’ve already checked that, Dave,” remarked Marlowe. “It agrees very well. Dr Kingsley’s values give about seventeen months.”

“Perhaps a little less than that,” observed Kingsley. “You get seventeen months if you don’t allow for the acceleration of the Cloud as it approaches the Sun. It’s moving at about seventy kilometres per second at the moment, but by the time it reaches the Earth it’ll have speeded to about eighty. The time required for the Cloud to reach the Earth works out at nearly sixteen months.”

Herrick quietly took charge of the discussion.

“Well, now that we understand each other’s point of view, what conclusions can we reach? It seems to me that we have both been under some misapprehension. For our part we thought of a much larger cloud lying considerably outside the solar system, while, as Dr Kingsley says, he thought of a condensed body within the solar system. The truth lies somewhere between these views. We have to do with a rather small cloud that is already within the solar system. What can we say about it?”

“Quite a bit,” answered Marlowe. “Our measurement of the angular diameter of the Cloud as about two and a half degrees, combined with Dr Kingsley’s distance of about 21 astronomical units, shows that the Cloud has a diameter about equal to the distance from the Sun to the Earth.”

“Yes, and with this size we can immediately get an estimate of the density of the material in the Cloud,” went on Kingsley. “It looks to me as though the volume of the cloud is roughly 1040 c.c. Its mass is about 1·3 × 1030 gm., which gives a density of 1·3 × 10–10 gm. per cm3.”

A silence fell on the little company. It was broken by Emerson.

“That’s an awful high density. If the gas comes between us and the Sun it’ll block out the Sun’s light completely. It looks to me as if it’s going to get almighty cold here on Earth!”

“That doesn’t necessarily follow,” broke in Barnett. “The gas itself may get hot, and heat may flow through it.”

“That depends on how much energy is required to heat the Cloud,” remarked Weichart.

“And on its opacity, and a hundred and one other factors,” added Kingsley. “I must say it seems very unlikely to me that much heat will get through the gas. Let’s work out the energy required to heat it to an ordinary sort of temperature.”

He went out to the blackboard, and wrote:

“That looks sound enough,” commented Weichart. “And I’d say that what you’ve got is very much a minimum estimate.”

“That’s so,” nodded Kingsley. “And my minimum is already very much longer than it will take the Cloud to pass us by. At a speed of 80 kilometres per second it’ll sweep across the Earth’s orbit in about a month. So it looks to me pretty certain that if the Cloud does come between us and the Sun it’ll cut out the heat from the Sun quite completely.”

“You say if the Cloud comes between us and the Sun. Do you think there’s a chance it may miss us?’ asked Herrick.

“There’s certainly a chance, quite a chance I’d say. Look here.”

Kingsley moved again to the blackboard.

“Here’s the Earth’s orbit round the Sun. We’re here at the moment. And the Cloud, to draw it to scale, is over here. If it’s moving like this, dead set for the Sun, then it’ll certainly block the Sun. But if it’s moving this second way, then it could well miss us altogether.”

“It looks to me as if we’re rather lucky,” Barnett laughed uneasily. “Because of the Earth’s motion round the Sun, the Earth will be on the far side of the Sun sixteen months hence when the Cloud arrives.”

“That only means that the Cloud will reach the Sun before it reaches the Earth. It won’t stop the sunlight being blocked out if the Sun gets covered, as in Kingsley’s case (a),” Marlowe remarked.

“The point about your cases (a) and (b),” said Weichart, “is that you only get case (a) if the Cloud has almost exactly zero angular momentum about the Sun. It only needs a very slight angular momentum and we have case (b).”

“That’s exactly it. Of course my case (b) was only one example. The Cloud could equally well sweep past the Sun and the Earth on the other side, like this:”

“Do we have anything to say about whether the Cloud is coming dead at the Sun or not?’ asked Herrick.

“Not on the observational side,” answered Marlowe. “Look at Kingsley’s drawing of the present situation. Only a very slight difference of velocity makes a big difference, all the difference between the Cloud hitting and missing. We can’t say yet which it’s to be, but we can find out as the Cloud comes in nearer.”

“So that’s one of the important things to be done,” concluded Herrick.

“Can you say anything more from the theory?”

“No, I don’t think we can; the calculations aren’t accurate enough.”

“Astonishing to hear you distrusting calculations, Kingsley,” remarked the Astronomer Royal.

“My calculations were based on your observations, A.R.! Anyway I agree with Marlowe. The thing to do is to keep a close watch on the Cloud. It should be possible to see whether we’re going to have a hit or a miss without too much trouble. A month or two should settle it, I suppose.”

“Right!’ answered Marlowe. “You can rely on us to watch this fellow from now on as carefully as if it was made of gold.”

After lunch Marlowe, Kingsley, and the Astronomer Royal were sitting in Herrick’s office. Herrick had explained the plan of writing a joint report.

“And I think our conclusions are very clear. May I just outline them for you?

“So if the material of the Cloud interposes itself between the Sun and the Earth, the Earth will be plunged into darkness. Observations are not yet sufficiently definitive to decide whether or not this will occur, but further observations should be capable of deciding this question.”

“And I think we can go a little further concerning future observations,” Herrick went on. “Optical observations will be prosecuted here with all energy. And we feel that work by the Australian radio astronomers will be complementary to ours, particularly with regard to keeping a watch on the line of sight motion of the Cloud.”

“That seems to sum up the situation admirably,” agreed the Astronomer Royal.

“I propose that we proceed with the report at full speed, that we four sign it, and that it be communicated to our respective Governments forthwith. I hardly need say that the whole matter is highly secret, or at least that we should treat it as so. It is rather unfortunate that so many are aware of the position, but I believe that we can rely on everybody proceeding with great discretion.”

Kingsley did not agree with Herrick on this point. Also he was feeling very tired, which no doubt made him express his views rather more forcibly than he would otherwise have done.

“I’m sorry, Dr Herrick, but I don’t follow you there. I see no reason why we scientists should go to the politicians like a lot of dogs thumping our tails, saying “Please, sir, here’s our report. Please give us a pat on the back and perhaps even a biscuit if you feel so disposed.” I can’t see the slightest point in having to do with a crowd of people that can’t even run society properly during normal times when there’s no serious stress. Will the politicians pass statutes to stop the Cloud coming? Will they be able to prevent it cutting off the light of the Sun? If they can, then consult them by all means, but if they can’t, let’s leave them out of the picture altogether.”

Dr Herrick was quietly firm.

“I’m sorry, Kingsley, but as I see it the United States Government and the British Government are the democratically elected representatives of our respective peoples. I regard it as our obvious duty to make this report, and to maintain silence until our Governments have made a pronouncement on it.”

Kingsley stood up.

“I’m sorry if I seem brusque. I’m tired. I want to go and get some sleep. Send your report if you wish, but please understand that if I decide to say nothing publicly for the time being, it will be because I wish to say nothing, not because I feel under any form of compulsion or duty. And now if you’ll excuse me, I’d like to get round to my hotel.”

When Kingsley had gone, Herrick looked at the Astronomer Royal.

“Dr Kingsley seems a trifle … er …”

“A trifle unstable?’ said the Astronomer Royal. He smiled and went on:

“That’s not very easy to say. Whenever you can follow his reasoning, Kingsley is always very sound and often brilliantly deductive. And I am inclined to think this is always so. I think he seemed rather odd just now because he was arguing from unusual premises, rather than because his logic was faulty. Kingsley probably thinks about society in quite a different way from us.”

“Anyway I think that while we work on this report it would be a good idea if Marlowe were to look after him,” remarked Herrick.

“That’s fine,” Marlowe agreed, still struggling with his pipe, “we’ve got a lot of astronomy to talk about.”

When Kingsley came down to breakfast the following morning he found Marlowe waiting.

“Thought you might like to drive out for the day into the desert.”

“Spendid, there’s nothing I’d like better. I’ll be ready in a few minutes.”

They drove out of Pasadena, turned sharply right off Highway 118 at La Canada, then cut through the hills, past the side road to Mount Wilson, and so on to the Mohave Desert. Three more hours’ driving brought them under the wall of the Sierra Nevada, and at last they could see Mount Whitney plastered with snow. The far desert stretching towards Death Valley was veiled in a blue haze.

“There are a hundred and one tales,” said Kingsley, “of what a man feels like when he’s told that he’s only got a year to live — incurable diseases, and so on. Well, it’s odd to think that every one of us probably only has a little more than a year to live. A couple of years hence, the mountains and the desert will be much the same as they are now, but there’ll be no you and me, no people at all to drive along through it.”

“Oh my God, you’re much too pessimistic,” grunted Marlowe. “As you said yourself, there’s every chance that the Cloud will sweep to one side or the other of the sun, and give us a complete miss.”

“Look, Marlowe, I didn’t want to press you too much yesterday, but if you’ve got a photograph going back a number of years you must have a pretty good idea of whether or not there’s any proper motion. Did you find any?”

“None that I could swear to.”

“Then surely that’s pretty good evidence that the Cloud is coming dead towards us, or at any rate dead towards the Sun.”

“You might say so, but I can’t be certain.”

“So what you mean is that the Cloud is probably going to hit us, but there’s still a chance that it might not.”

“I still think you’re being unduly pessimistic. We’ll just have to see what we can learn during the next month or two. And anyway, even if the Sun is blotted out, don’t you think we can see it through? After all it’ll only be for about a month.”

“Well, let’s go into it from scratch,” began Kingsley. “After a normal sunset the temperature goes down. But the decline is limited by two effects. One is the heat stored in the atmosphere, which acts as a reservoir that keeps us warm. But I reckon that this reservoir would soon become exhausted, I calculate, in less than a week. You’ve only got to think how cold it gets at night out here in the desert.”

“How do you square that with the Arctic night, when the Sun may be invisible for a month or more? I suppose the point is that the Arctic is constantly receiving air from lower latitudes; and that this air has been heated by the Sun.”

“Of course. The Arctic is constantly warmed by air that flows up from tropical and temperate regions.”

“What was your other point?”

“Well, the water vapour in the atmosphere tends to hold in the heat of the Earth. In the desert, where there’s very little water vapour, the temperature goes down a long way at night. But in places where there’s lots of humidity, like New York in summer, there’s very little cooling at night.”

“And what does that lead you to?”

“You can see what will happen,” continued Kingsley. “For the first day or two after the Sun is hidden — if it is shut out, that’s to say — there won’t be a great deal of cooling, partly because the air will be still warm and partly because of the water vapour. But as the air cools the water will gradually turn, first into rain, then into snow, which will fall to the ground. So the water vapour will be removed from the air. It may take four or five days for that to happen, perhaps even a week or ten days. But then the temperature will go racing down. Within a fortnight we shall have a hundred degrees of frost, and within a month there’ll be two hundred and fifty or more.”

“You mean it’ll be as bad here as it is on the Moon?”

“Yes, we know that at sunset on the Moon the temperature declines by over three hundred degrees in a single hour. Well, it’ll be much the same here except that it’ll take longer because of our atmosphere. But it’ll come to the same thing in the end. No, Marlowe, I don’t think we can last out a month, even though it doesn’t seem very long.”

“You reject the possibility that we might keep warm the same way as they keep warm in winter in the Canadian prairies, by efficient central heating?”

“It’s just possible I suppose that some buildings are sufficiently well insulated to stand the tremendous temperature gradients that’ll be set up. They’ll have to be very exceptional, because when we build offices and houses, and so on, we don’t build with these temperature conditions in mind. Still I’ll grant you that a few people may survive, people that have specially well designed buildings in cold climates. But I think there’s no chance at all for anyone else. The tropical peoples with their ramshackle houses will be in a very poor case.”

“Sounds very grim, doesn’t it?”

“I suppose the best thing will be to find a cave where we can get deep underground.”

“But we need air to breathe. What should we do when that gets very cold?”

“Have a heating plant. That wouldn’t be too difficult. Heat the air going into a deep cave. That’s what all the Governments that Herrick and the A.R. are so keen on will do. They’ll have nice warm caves, while you and me, Marlowe my boy, will get the icicle treatment.”

“I don’t believe they’re quite as bad as that,” Marlowe laughed.

Kingsley went on quite seriously:

“Oh, I agree they won’t be blatant about it. There’ll be good reasons for everything they do. When it becomes clear that only a tiny nucleus of people can be saved, then it’ll be argued that the lucky fellows must be those who are most important to society; and that, when it’s boiled down and distilled, will turn out to mean the political fraternity, field-marshals, kings, archbishops, and so on. Who are more important than these?”

Marlowe saw that he had better change the subject slightly.

“Let’s forget about humans for the time being. How about other animals and plants?”

“All growing plants will be killed, of course. But plant seeds will probably be all right. They can stand intense cold and still be capable of germination as soon as normal temperatures return. There’ll probably be sufficient seeds around to ensure that the flora of the planet remains essentially undamaged. The case is very different with the animals. I don’t see any large land animal surviving at all, except a small number of men, and perhaps a few animals that men take into shelter with them. Small furry burrowing animals may be able to get deep enough into the ground to withstand the cold, and by hibernating they may save themselves from dying for lack of food.

“Sea animals will be very much better off. Just as the atmosphere is a reservoir of heat, the sea is a vastly greater reservoir. The temperature of the seas won’t fall very much at all, so the fish will probably be all right.”

“Now isn’t there a fallacy in your whole argument?’ exclaimed Marlowe with considerable excitement. “If the seas stay warm, then the air over the seas will stay warm. So that there’ll always be a supply of warm air to replenish the cold air over the land!”

“I don’t agree there,” answered Kingsley. “It isn’t even certain that the air over the seas will stay warm. The seas will cool enough for them to freeze up at the surface although the water lower down will stay quite warm. And once the seas freeze over, there won’t be much difference between the air over the land and the sea. It’ll all get extremely cold.”

“Unfortunately what you say sounds right. So it looks as if a submarine might be the right place to be!”

“Well, a sub wouldn’t be able to surface because of the ice, so a complete air supply would be needed and that wouldn’t be easy. Ships wouldn’t be any good either because of the ice. And there’s another objection to your argument. Even if the air over the sea did stay comparatively warm, it would not supply heat to the air over the land, which being cold and dense would form tremendous stable anticyclones. The cold air would stay on the land and the warm air on the sea.”

“Look here, Kingsley,” laughed Marlowe, “I’m not going to have my optimism damped by your pessimism. Have you thought of this point? There may be quite an appreciable radiation temperature inside the Cloud itself. The Cloud may have an appreciable heat of its own, and this might compensate us for the loss of sunlight, always supposing — as I keep saying — that we do find ourselves inside the Cloud!”

“But I thought the temperature inside the interstellar clouds was always very low indeed?”

“That’s the usual sort of cloud, but this one is so much denser and smaller that its temperature may be anything at all, so far as we know. Of course it can’t be extremely high, otherwise the Cloud would be shining bright, but it can be high enough to give us all the heat we want.”

“Optimist, did you say? Then what’s to stop the Cloud being so hot that it boils us up? I didn’t realize there was so much uncertainty about the temperature. Frankly, I like this possibility even less. It’ll be completely disastrous if the Cloud is too hot.”

“Then we shall have to go into caves and refrigerate our air supply!”

“But that isn’t so good. Plant seeds can stand cold but they can’t stand excessive heat. It wouldn’t be much good for Man to survive if the whole flora was destroyed.”

“Seeds could be stored in the caves, along with men, animals, and refrigerators. My God, it puts old Noah to shame, doesn’t it?”

“Yes, maybe some future Saint-Saëns will write the music for it.”

“Well, Kingsley, even if this chat hasn’t been exactly consoling, at least it’s brought out one highly important point. We must find the temperature of that Cloud and without delay too. It’s obviously another job for the radio boys.”

“Twenty-one centimetre?’ asked Kingsley.

“Right! You have a team at Cambridge that could do it, haven’t you?”

“They’ve started in on the twenty-one centimetre game quite recently, and I think they could give us an answer to this point pretty quickly. I’ll get on to ’em as soon as I get back.”

“Yes, and let me know how it comes out as soon as you can. You know, Kingsley, while I don’t necessarily go along with all you say about politics, I don’t quite like the idea of everything going outside our control. But I can’t do anything myself. Herrick has asked for the whole business to be put on the secret list, and he’s my boss, and I can’t go above him. But you’re a free agent, especially after what you told him yesterday. So you can look into this business. I should get ahead with it as fast as you can.”

“Don’t worry, I will.”

The drive was a long one, and it was evening by the time they dropped down through the Cajon Pass to San Bernardino. They stopped for an excellent dinner at a restaurant of Marlowe’s choice on the western side of the township of Arcadia.

“I’m not normally keen on parties,” Marlowe said, “but I think a party away from scientists would do us both good tonight. One of my friends, a business tycoon over San Marino way, invited me to drive over.”

“But I can’t go along and gatecrash.”

“Nonsense, of course you can come — a guest from England! You’ll be the lion of the party. Probably half a dozen film moguls from Hollywood will want to sign you up on the spot.”

“All the more reason for not going,” said Kingsley. But he went all the same.

The house of Mr Silas U. Crookshank, successful real estate operator, was large, spacious, well decorated. Marlowe was right about Kingsley’s reception. A super-large tumbler of hard liquor, which Kingsley took to be Bourbon whisky, was thrust into his hand.

“That’s great,” said Mr Crookshank. “Now we’re complete.”

Why they were complete Kingsley never discovered.

After polite talk to the vice-president of an aircraft company, to the director of a large fruit-growing company, and other worthy men, Kingsley at last fell into conversation with a pretty, dark girl. They were interrupted by a handsome fair woman who laid a hand on each of their arms.

“Come along, you two,” she said in a low, husky, much cultivated voice. “We’re going along to Jim Halliday’s place.”

When he saw that the dark girl was going to accept Husky Voice’s plan, Kingsley decided he might as well go along too. No point in bothering Marlowe, he thought. He could get back to his hotel somehow.

Jim’s place was a good deal smaller than the residence of Mr S. U. Crookshank, but nevertheless they managed to clear a floor space on which two or three couples began dancing to the somewhat raucous strains of a gramophone. More drinks were handed round. Kingsley was glad of his, for he was no shining light of the dancing world. The dark girl was engaged by two men, to whom Kingsley, in spite of the whisky, took a hearty dislike. He decided to muse on the state of the world until he could prise the girl loose from the two bounders. But it was not to be. Husky Voice came across to him. “Let’s dance, honey,” she said.

Kingsley did his best to adjust himself to the creeping rhythm, but apparently he did not succeed in gaining his partner’s approval.

“Why don’t you relax, sweetheart?’ the voice breathed.

No remark could have been better calculated to baffle Kingsley, for he saw no prospect of relaxing in the overcrowded space. Was he expected to go limp, leaving Husky Voice to support his dead weight?

He decided to counter with nonsense of an equal order.

“I never feel too cold, do you?”

“Say, that’s darned cute,” said the woman in a sort of amplified whisper.

In a state of acute desperation Kingsley edged her off the floor, and grabbing his glass took a deep swig. Spluttering violently, he raced for the entrance hall, where he remembered seeing a telephone. A voice behind him said:

“Hello, looking for something?”

It was the dark girl.

“I’m ringing for a taxi. In the words of the old song, “I’m tired and I want to go to bed.” ”

“Is that quite the right thing to say to a respectable young woman? Seriously though, I’m going myself. I’ve got a car, so I’ll give you a lift. Forget about the taxi.”

The girl drove smartly into the outskirts of Pasadena.

“It’s dangerous to drive too slowly,” she explained. “At this time of night the cops are on the look-out for drunks and for people going home from parties. And they don’t just pick up cars that are driven too fast. Slow driving makes ’em suspicious too.” She switched on the dashboard light to check the speed. Then she noticed the fuel gauge.

“Hell, I’m almost out of gas. We’d better stop at the next station.”

It was only when she came to pay the attendant at the station that she discovered that her handbag was not in the car. Kingsley settled for the petrol.

“I can’t think where I can have left it,” she said. “I thought it was in the back of the car.”

“Was there much in it?”

“Not a great deal. But the trouble is I don’t see how I’m going to get into my apartment. The door key was in it.”

“That’s distinctly awkward. Unfortunately I’m not a great hand at picking locks. Is it possible to climb in somehow?”

“Well, I think it might be, if I had some help. There’s a highish window that I always leave open. I couldn’t reach it alone, but I might if you gave me a lift. Would you mind? It’s not very far from here.”

“Not in the least,” said Kingsley. “I rather fancy myself as a burglar.”

The girl was right about the window being high. It could only be reached by one person standing on another’s shoulder. The manoeuvre wouldn’t be altogether easy.

“I’d better do the climbing,” said the girl. “I’m lighter than you.”

“So instead of the dashing cracksman, I’m to be cast in the role of a carpet?”

“That’s right,” said the girl as she pulled off her shoes. “Now get down, so I can climb on your shoulders: Not so far down, or you’ll never get up again.”

Once the girl nearly slipped, but she recovered balance by knotting her hand in Kingsley’s hair.

“Stop pulling my head off,” he grunted.

“Sorry, I knew I shouldn’t have drunk so much gin.”

Eventually it was done. The window was pushed open, and the girl disappeared inside, head and shoulders first, feet last. Kingsley picked up the shoes and walked over to the door. The girl opened it. “Come in,” she said. “I’ve laddered my nylons. I hope you’re not shy about coming in?”

“I’m not in the least shy. I want my scalp back please if you’ve finished with it.”

It was nearly lunch time when Kingsley arrived at the Observatory the following day. He went straight to the Director’s office, where he found Herrick, Marlowe, and the Astronomer Royal.

“My God, he looks shockingly dissipated,” thought the Astronomer Royal.

“My God, the whisky treatment seems to have fixed him,” thought Marlowe.

“He looks even more unstable,” thought Herrick.

“Well, well, are all those reports finished?’ said Kingsley.

“All finished and waiting for your signature,” answered the Astronomer Royal. “We were wondering where you’d got to. Our plane is booked back for tonight.”

“Plane booked back? Nonsense. First we race over half the world through all those damned airports, and now that we’re here, enjoying the sunshine, you want to rush back again. It’s ridiculous, A.R. Why don’t you relax?”

“You seem to forget that we’ve got very serious business to attend to.”

“The business is serious enough. I’m with you there, A.R. But I tell you in all seriousness that it’s a business that neither you nor anyone else can attend to. The Black Cloud is on its way and neither you, nor all the King’s horses nor all the King’s men, nor the King himself, can stop it. My advice is to drop all this nonsense about a report. Get out into the sunshine while it’s still with us.”

“We were already acquainted with your views, Dr Kingsley, when the Astronomer Royal and I decided to fly east tonight,” broke in Herrick in measured tones.

“Am I to understand that you are going to Washington, Dr Herrick?”

“I have already arranged an appointment with the President’s secretary.”

“Then in that case I think it would be as well if the Astronomer Royal and I were to travel on to England without delay.”

“Kingsley, that is exactly what we’ve been trying to tell you,” growled the Astronomer Royal, thinking that in some ways Kingsley was the most obtuse person he had ever met.

“It wasn’t exactly what you told me, A.R., although it may have seemed that way to you. Now about those signatures. In triplicate, I suppose?”

“No, there are only two master copies, one for me and one for the Astronomer Royal,” answered Herrick. “Would you sign here?”

Kingsley took out his pen, scribbled his name twice, and said:

“You’re quite sure, A.R., that our plane to London is booked?”

“Yes, of course.”

“Then that seems all right. Well, gentlemen, I shall be at your disposal at my hotel from five o’clock onwards. But in the meantime there are various important matters that I must attend to.”

And with that Kingsley walked out of the Observatory.

The astronomers in Herrick’s room looked at each other in surprise.

“What important matters?’ said Marlowe.

“Heaven knows,” answered the Astronomer Royal. “Kingsley’s ways of thinking and behaving are more than I pretend to understand.”

Herrick left the east-bound plane at Washington. Kingsley and the Astronomer Royal flew on to New York, where they had a three-hour wait before boarding the London plane. There was some doubt as to whether they could take off because of fog. Kingsley was greatly agitated until eventually they were told to proceed to gate 13 and to have their boarding cards ready. Half an hour later they were in the air.

“Thank God for that,” said Kingsley, as the plane headed steadily to the north-east.

“I would agree that there are many things for which you ought to thank God, but I don’t see that this is one of them,” remarked the Astronomer Royal.

“I would be glad to explain, A.R., if I thought that the explanation would commend itself to you. But as I fear it wouldn’t, let’s have a drink. What’ll you have?”