The Black Cloud

A Meeting in London

Four days earlier in London a remarkable meeting had been held in the rooms of the Royal Astronomical Society. The meeting had been called, not by the Royal Astronomical Society itself, but by the British Astronomical Association, an association essentially of amateur astronomers.

Chris Kingsley, Professor of Astronomy in the University of Cambridge, travelled by train in the early afternoon to London for the meeting. It was unusual for him, the most theoretical of theoreticians, to be attending a meeting of amateur observers. But there had been rumours of unaccounted discrepancies in the positions of the planets Jupiter and Saturn. Kingsley didn’t believe it, but he felt that scepticism should rest on solid ground, so he ought to hear what the chaps had to say about it.

When he arrived at Burlington House in time for the four o’clock tea, he was surprised to see that quite a number of other professionals had already arrived, including the Astronomer Royal. “Never heard of anything like this before at the B.A.A. The rumours must have been put around by some new publicity agent,” he thought to himself.

When Kingsley went in to the meeting room some half hour later he saw a vacant place on the front row by the Astronomer Royal. No sooner had he sat down than a Dr Oldroyd who was in the chair began the meeting in the following terms:

“Ladies and gentlemen, we meet here today to discuss some new and exciting results. But before I call on the first speaker I would like to say how pleased we are to see so many distinguished visitors. I am confident they will find that the time they have consented to spend with us will not have been wasted, and I feel that the important role of the amateur in astronomy will be demonstrated yet once again.”

At this Kingsley grinned inwardly to himself, and several of the other professionals squirmed in their seats. Dr Oldroyd went on:

“I have great pleasure in asking Mr George Green to address us.”

Mr George Green jumped up from his seat half-way down the room. He then bustled forward to the rostrum, clutching a large pile of papers in his right hand.

For the first ten minutes Kingsley listened with polite attention as Mr Green showed slides of his private telescopic equipment. But when the ten minutes lengthened to a quarter of an hour he began to fidget, and for the next half hour he lived in torment, first crossing his legs one way, then the other, then squirming round every minute or so to look at the clock on the wall. It was all in vain, for Mr George Green went right ahead with the bit firmly between his teeth. The Astronomer Royal kept glancing at Kingsley, a quiet smile on his face. The other professionals hugged themselves with delight. Their eyes never left Kingsley. They were calculating when the outburst would come.

The outburst never came, for Mr Green suddenly seemed to remember the purpose of his talk. Quitting the description of his beloved equipment, he began to throw off his results, rather like a dog shaking itself after a bath. He had observed Jupiter and Saturn, measuring their positions with care, and he had found discrepancies from the Nautical Almanac. Running to the blackboard he wrote down the following figures, and then sat down:

Discrepancy in Longitude Discrepancy in Declination

Jupiter+1 minute 29 seconds–49 seconds Saturn+42 seconds–17 seconds

Kingsley never heard the loud applause offered to Mr Green as a reward for his address, for Kingsley was choking with rage. He had come up to the meeting expecting to be told of discrepancies amounting to no more than a few tenths of a second at most. These he could have attributed to inaccurate, incompetent measurement. Or there might have been a subtle mistake of a statistical nature. But the figures that Mr Green had written up on the board were preposterous, fantastic, so large that a blind man could have seen them, so large that Mr George Green must have made some quite outrageous blunder.

It must not be thought that Kingsley was an intellectual snob, that he objected to an amateur on principle. Less than two years previously he had listened in the very same room to a paper presented by an entirely unknown author. Kingsley had immediately perceived the quality and competence of the work and was the first person to give public praise to it. Incompetence was Kingsley’s béte noire, not incompetence performed in private but incompetence paraded in public. His irritation in this respect could be aroused in art and music as much as in science.

On this occasion he was a seething cauldron of wrath. So many ideas flashed through his head that he was unable to decide on any one particular comment, it seemed such a pity to waste the others. Before he could reach a decision, Dr Oldroyd sprang a surprise:

“I have great pleasure,” said he, “in calling on the next speaker, the Astronomer Royal.”

It had been the Astronomer Royal’s first intention to speak shortly and to the point. Now he was unable to resist the temptation to expatiate at length, just for the pleasure of watching Kingsley’s face. Nothing could have been calculated to torment Kingsley more than a repetition of Mr George Green’s performance, and this is just what the Astronomer Royal produced. He first showed slides of the equipment at the Royal Observatory, slides of observers operating the equipment, slides of the equipment taken to pieces; and he then went on to explain the detailed operation of the equipment in terms that might have been chosen for the benefit of a backward child. But all this he did in measured confident tones, unlike the rather hesitant manner of Mr Green. After some thirty-five minutes of this he began to feel that Kingsley might be in real medical danger, so he decided to cut the cackle.

“Our results in broad outline confirm what Mr Green has already told you. Jupiter and Saturn are out of position and to amounts that are of the general order given by Mr Green. There are some small discrepancies between his results and ours but the main features are the same.

“At the Royal Observatory we have also observed that the planets Uranus and Neptune are out of their positions, not it is true to the same extent as Jupiter and Saturn, but nevertheless in very appreciable amounts.

“Finally I may add that I have received a letter from Grottwald in Heidelberg, in which he says that the Heidelberg Observatory has obtained results that accord closely with those of the Royal Observatory.”

Whereon the Astronomer Royal returned to his seat. Dr Oldroyd immediately addressed the meeting:

“Gentlemen, you have heard presented to you this afternoon results that I venture to suggest are of the very first importance. Today’s meeting may well become a landmark in the history of astronomy. It is not my wish to take up any more of your time as I expect you will have much to say. In particular I expect our theoreticians will have much to say. I should like to begin the discussion by asking Professor Kingsley whether he has any comment he would like to make.”

“Not while the law of slander is still operative,” whispered one professional to another.

“Mr Chairman,” began Kingsley, “while the two previous speakers were addressing us I had ample opportunity to perform a fairly lengthy calculation.”

The two professionals grinned at each other, the Astronomer Royal grinned to himself.

“The conclusion I have arrived at may be of interest to the meeting. I find that if the results that have been presented to us this afternoon are correct, I say if they are correct, then a hitherto unknown body must exist in the vicinity of the solar system. And the mass of this unknown body must be comparable with or even greater than the mass of Jupiter itself. While it must be granted implausible to suppose that the results given to us arise from mere observational errors, I say mere observational errors, it may also be thought implausible that a body of such large mass existing within the solar system, or on the periphery of the solar system, could so far have remained undetected.”

Kingsley sat down. The professionals who understood the general trend of his argument, and what lay under it, felt that he had made his point.

Kingsley glowered at the railwayman who asked to see his ticket as he boarded the 8.56 p.m. train from Liverpool Street to Cambridge. The man fell back a pace or two, as well he might, for Kingsley’s rage had not been assuaged by the meal he had just eaten, a meal consisting of poor food badly cooked, condescendingly served in pretentious but slovenly conditions. Only its price had been ample. Kingsley stamped through the train looking for a compartment where he could bite the carpet in solitary splendour. Moving quickly through a first-class carriage he caught a glimpse of the back of a head that he thought he recognized. Slipping into the compartment, he dropped down by the Astronomer Royal.

“First-class, nice and comfortable. Nothing like working for the government, eh?”

“Quite wrong, Kingsley. I’m going up to Cambridge for a Trinity Feast.”

Kingsley, still acutely conscious of the execrable dinner he had just consumed, pulled a wry face.

“Always amazes me the way those Trinity beggars feed themselves,” he said. “Feasts on Mondays, Wednesdays, and Fridays, and four square meals on each of the other days of the week.”

“Surely it’s not quite as bad as that. You seem quite put out today, Kingsley. In trouble of any sort?”

Metaphorically the Astronomer Royal was hugging himself with delight.

“Put out! Who wouldn’t be put out, I’d like to know. Come on, A.R.! What was the idea of that vaudeville stunt this afternoon?”

“Everything that was said this afternoon was plain sober fact.”

“Sober fact, my eye! It would have been much more sober if you’d got up on the table and done a clog dance. Planets a degree and a half out of position! Rubbish!”

The Astronomer Royal lifted down his brief case from the rack and took out a large file of papers on which a veritable multitude of observations was entered.

“Those are the facts,” he said. “In the first fifty or so pages you’ll find the raw observations of all the planets, day-by-day figures over the last few months. In the second table you’ll find the observations reduced to heliocentric co-ordinates.”

Kingsley studied the papers silently for the best part of an hour, until the train reached Bishop’s Stortford. Then he said:

“You realize, A.R., that there isn’t the slightest chance of getting away with this hoax? There’s so much stuff here that I can easily tell whether it’s genuine. Can I borrow these tables for a couple of days?”

“Kingsley, if you imagine that I would go to the trouble of staging an elaborate — hoax as you call it, primarily with the object of deceiving you, of taking a rise out of you, then all I can say is that you flatter yourself unduly.”

“Let’s put it this way,” answered Kingsley. “There are two hypotheses that I can make. Both at first sight seem incredible, but one of them must be right. One hypothesis is that a hitherto unknown body with a mass of the same order as Jupiter has invaded the solar system. The second hypothesis is that the Astronomer Royal has taken leave of his senses. I don’t want to give offence, but quite frankly the second alternative seems to me less incredible than the first.”

“What I admire about you, Kingsley, is the way you refuse to mince matters — curious phrase that.” The Astronomer Royal reflected thoughtfully for a moment. “You should go in for politics one day.”

Kingsley grinned. “Can I have these tables for a couple of days?”

“What do you propose to do?”

“Well, two things. I can check the consistency of the whole business and then I’ll find out just where the intruding body is located.”

“And you’ll do this how?”

“First I’ll work backwards from the observations of one of the planets — Saturn might be the best one to choose. This’ll determine the distribution of the intruding body, or intruding material if it isn’t in the form of a discrete body. This’ll be much the same thing as the J. C. Adams — Le Verrier determination of the position of Neptune. Then once I’ve got the intruding material pinned down, I’ll work the calculation forwards. I’ll work out the disturbances of the other planets Jupiter, Uranus, Neptune, Mars, etcetera. And when I’ve done that, I’ll compare my results with your observations of these other planets. If my results agree with the observations then I’ll know there’s no hoax. But if they don’t agree — well!”

“That’s all very fine,” said the Astronomer Royal, “but how do you propose to do all this in a couple of days?”

“Oh, by using an electronic computer. Fortunately I’ve got a programme already written for the Cambridge computer. It’ll take me all tomorrow modifying it slightly, and to write a few subsidiary routines to deal with this problem. But I ought to be ready to start calculating by tomorrow night. Look here, A.R., why don’t you come to the lab after your Feast? If we work through tomorrow night, we ought to get the matter settled very quickly.”

The following day was most unpleasant; it was cold, rainy, and a thin mist covered the town of Cambridge. Kingsley worked all through the morning and into mid-afternoon before a blazing fire in his College rooms. He worked steadily, writing an astonishing scrawl of symbols of which the following is a short sample, a sample of the code by which the computer was instructed as to how it should perform its calculations and operations:

At about three-thirty he went out of College, thoroughly muffled up and sheltering under his umbrella a voluminous sheaf of papers. He worked his way by the shortest route to Corn Exchange Street, and so into the building where the computing machine was housed, the machine that could do five years of calculation in one night. The building had once been the old Anatomy School and was rumoured by some to be haunted, but this was far from his mind as he turned from the narrow street into the side door.

His first move was not to the machine itself, which in any case was being operated by others just at that moment. He still had to convert the letters and figures he had written into a form that the machine could interpret. This he did with a special kind of typewriter, a typewriter that delivered a strip of paper in which holes were punched, the pattern of the holes corresponding to the symbols that were being typed. It was the holes in the paper that constituted the final instructions to the computer. Not one single hole among many thousands must be out of its proper place, otherwise the machine would compute incorrectly. The typing had to be done with meticulous accuracy, with literally one hundred per cent accuracy.

It was not until nearly six o’clock that Kingsley was satisfied that everything was satisfactorily in order, checked and double-checked. He made his way to the top floor of the building where the machine was housed. The heat of many thousands of valves made the machine-room pleasantly warm and dry on this cold damp January day. There was the familiar hum of electric motors and the rattle of the teleprinter.

The Astronomer Royal had spent a pleasant day visiting old friends, and a delightful evening at the Trinity Feast. Now at about midnight he felt much more like sleeping than sitting up at the Mathematical Laboratory. Still, perhaps he’d better go along and see what the crazy fellow was up to. A friend offered to take him by car to the lab., so there he was standing in the rain, waiting for the door to be opened. At length Kingsley appeared.

“Oh hello, A.R.,” he said. “You’ve come at just the right moment.”

They walked up several flights of stairs to the computer.

“Have you got some results already?”

“No, but I think I’ve got everything working now. There were several mistakes in the routines I wrote this morning and I’ve spent the last few hours in tracking ’em down. I hope I’ve got them all. I think so. Provided nothing goes wrong with the machine, we should get some decent results in an hour or two. Good feast?”

It was about two o’clock in the morning when Kingsley said:

“Well, we’re nearly there. We should have some results in a minute or two.”

Sure enough five minutes later there was a new sound in the room, the chatter of the high-speed punch. Out of the punch came a thin strip of paper about ten yards long. The holes in the paper gave the results of a calculation that it would have taken an unaided human a year to perform.

“Let’s have a look at it,” said Kingsley as he fed the paper tape into the teleprinter. Both men watched as row after row of figures were typed out.

“The lay-out isn’t very good, I’m afraid. Perhaps I’d better interpret. The first three rows give the values of the set of parameters I put into the calculations to take account of your observations.”

“And how about the position of the intruder?’ asked the Astronomer Royal.

“Its position and mass are given in the next four rows. But they’re not in a very convenient form — I said the lay-out isn’t very good. I want to use these results to calculate next what influence the intruder should have on Jupiter. This tape is in the right form for that.”

Kingsley indicated the paper strip that had just come out of the machine.

“But I shall have to do a little calculation myself before I can reduce the tabulated numbers to a really convenient form. Before I do that, let’s start the machine finding out about Jupiter.”

Kingsley pressed a number of switches. Then he put a large roll of paper tape into the ‘reader’ of the machine. After pressing another switch the reader began to unroll the tape.

“You see what happens,” said Kingsley. “As the tape is unrolled a light shines through the holes in it. The light then goes into this box here, where it falls on a photo-sensitive tube. This causes a series of pulses to go into the machine. This tape I’m just putting in gives instructions to the machine as to how it is to calculate the disturbance in the position of Jupiter, but the machine hasn’t had all its instructions yet. It still doesn’t know where the intruder is, or how massive it is, or how fast it’s moving. So the machine won’t start working yet.”

Kingsley was right. The machine stopped as soon as it had reached the end of the long roll of paper tape. Kingsley pointed to a small red light.

“This shows that the machine has stopped because the instructions aren’t complete yet. Now where’s that piece of tape we got out last time? That’s it on the table by you.”

The Astronomer Royal handed over the long strip of paper.

“And this supplies the missing piece of information. When this has gone in, the machine will know all about the intruder as well.”

Kingsley pressed a switch and in went the second piece of tape. As soon as it had run through the reader, just as the first tape had done before it, lights began to flash on a series of cathode-ray tubes.

“Off she goes. From now on for the next hour the machine will be multiplying a hundred thousand ten-figure numbers every minute. And while it does that, let’s make some coffee. I’m peckish, I haven’t had anything to eat since four o’clock yesterday afternoon.”

So the two men worked on through the night. It was greying dawn on a miserable January morning when Kingsley said:

“Well, that’s about it. We’ve got all the results here, but they need a bit of conversion before we can get to work on a comparison with your observations. I’ll get one of the girls to do that today. Look, A.R., I suggest you have dinner with me tonight, and then we’ll go over things with a tooth comb. Perhaps you’d like to slip along now and get a bit of sleep. I’ll stay on until the lab staff comes in.”

After dinner that night, the Astronomer Royal and Kingsley were again together in the latter’s rooms at Erasmus College. The dinner had been a particularly good one and they were both much at their ease as they drew up to the blazing fire.

“Lot of nonsense we hear nowadays about these closed stoves,” said the Astronomer Royal, nodding towards the fire. “They’re supposed to be very scientific, but there’s nothing scientific about ’em. The best form of heat is in the form of radiation from an open fire. Closed stoves only produce a lot of hot air that’s extremely unpleasant to breathe. They stifle you without warming you.”

“A lot of sense in that,” added Kingsley. “Never had any use for such devices myself. Now how about a spot of port before we get down to business? Or madeira, claret, or burgundy?”

“Very nice, I think I’d like the burgundy, please.”

“Good, I’ve got a quite nice Pommard ’57.”

Kingsley poured out two largish glasses, returned to his seat, and went on:

“Well, it’s all here. I’ve got my calculated values for Mars, Jupiter, Uranus, and Neptune. The agreement with your observations is fantastically good. I’ve made up a sort of synopsis of the main results here on these four sheets, one for each planet. You can see for yourself.”

The Astronomer Royal spent several minutes looking over the several sheets.

“This is most impressive, Kingsley. That computer of yours is certainly a quite fantastic instrument. Well, are you satisfied now? Everything fits into line. Everything fits the hypothesis of an external body invading the solar system. By the way, do you have the details of its mass, position, and motion? They’re not given here.”

“Yes, I’ve got those too,” answered Kingsley, picking another sheet out of a large file.

“And that’s just where the trouble arises. The mass comes out at nearly two-thirds of that of Jupiter.”

The Astronomer Royal grinned.

“I thought you estimated at the B.A.A. meeting that it would be equal to Jupiter at least.”

Kingsley grunted.

“Considering the distractions, that wasn’t a bad estimate, A.R. But look at the heliocentric distance, 21.3 astronomical units, only 21.3 times the Earth’s distance from the Sun. It’s impossible.”

“I don’t see why.”

“At that distance it must be easily visible to the naked eye. Thousands of people would have seen it.”

The Astronomer Royal shook his head.

“It doesn’t follow that the thing must be a planet like Jupiter and Saturn. It may have a much higher density and a lower albedo. That might make it a very difficult naked-eye object.”

“Even so, A.R., some telescopic sky survey would have picked it up. You see it’s in the night sky, somewhere south of Orion. Here are the co-ordinates; Right Ascension 5 hours 46 minutes, Declination minus 30 degrees 12 minutes. I don’t know the details of the sky very well, but that is somewhere south of Orion, isn’t it?”

The Astronomer Royal grinned again.

“When did you last look through a telescope, Kingsley?”

“Oh, about fifteen years ago, I suppose.”

“What happened then?”

“I had to show a party of visitors over the Observatory.”

“Well, don’t you think we ought to go up to the Observatory now and see what we can see, instead of arguing about it? It seems to me that this intruder, as we keep calling it, may not be a solid body at all.”

“You mean it might be a cloud of gas? Well, in some ways that would be better. It wouldn’t be so easily seen as a condensed body. But the cloud would have to be pretty localized, with a diameter not much greater than that of the Earth’s orbit. A pretty dense sort of cloud it would have to be too, about 10–10 gm. per cm3. A minute star in the process of formation perhaps?”

The Astronomer Royal nodded.

“We know that the very big gas clouds like the Orion nebula have average densities of perhaps 10–21 gm. per cm3. On the other hand, stars like the Sun with densities of 1 gm. per cm3 are constantly forming within the big gas clouds. This surely means that there must be patches of gas at all densities varying from say 10–21 gm. per cm3 at one extreme up to stellar densities at the other extreme. Your 10–10 gm. per cm3 is bang in the middle of this range, and looks quite plausible to me.”

“There is a great deal of truth in that, A.R. Clouds with that sort of density must exist, I suppose. But I think you were quite right about going up to the Observatory. I’ll give Adams a ring while you finish your wine, and I’ll get a taxi.”

When the two men reached the University Observatory the sky was overcast, and although they waited through the cold damp hours there was no sight of the stars that night. And so it was the following night, and the night after that. Thus did Cambridge lose the honour of the first detection of the Black Cloud, as it had lost the honour of the first detection of the planet Neptune more than a century before.

On 17 January, the day after Herrick’s visit to Washington, Kingsley and the Astronomer Royal again dined together in Erasmus. Again they made their way to Kingsley’s rooms after dinner. Again they sat before the fire, drinking Pommard ’57.

“Thank goodness we don’t have to sit up all night again. I think Adams can be trusted to ring through if the sky clears.”

“I really ought to be getting back to Herstmonceux tomorrow,” said the Astronomer Royal. “After all, we’ve got telescopes there too.”

“Evidently this damn weather has got you down the same as me. Look here, A.R., I’m in favour of throwing our hand in. I’ve drafted a cable to send to Marlowe in Pasadena. Here it is. They won’t be troubled by cloudy skies over there.”

The Astronomer Royal glanced down at the sheet of paper in Kingsley’s hand.

“Shall I send it?’ asked Kingsley, anxiously.

“Send it. I’m sleepy,” said the Astronomer Royal, good-naturedly stifling a yawn.

Kingsley had a lecture at nine a.m. the following morning, so he bathed, dressed, and shaved before eight. His ‘gyp’ had laid the table for breakfast.

“A wire for you, sir,” he said.

A quick glance showed the ‘wire’ to be a cable. Incredible, thought Kingsley, that they should have a reply so quickly from Marlowe. He was even more astonished when he opened the cable.

The aircraft climbed slowly, heading westwards. Kingsley and the Astronomer Royal relaxed in their seats. It was the first moment of ease since Kingsley had opened the cablegram that morning. First he had to postpone his lecture, then he had discussed the whole matter with the Secretary of the Faculties. It was not easy to leave the University at such short notice, but eventually it was arranged. By then it was eleven a.m. This left three hours to get to London, fix his visa, collect the tickets, and board the bus from Victoria to London airport. It had been something of a rush. Things were a little easier for the Astronomer Royal, who travelled abroad so much that he always had passports and visas ready for just such an emergency.

Both men pulled out books to read on the journey. Kingsley glanced at the Astronomer Royal’s book and saw a vivid cover featuring a gun fight among desperados.

“Heaven knows what he’ll be reading next,” thought Kingsley.

The Astronomer Royal looked at Kingsley’s book and saw it was Herodotus’ Histories.

“My God, he’ll be reading Thucydides next,” thought the Astronomer Royal.