The Comparison Star

by Cecilia Payne-Gaposchkin, Simulacrum · Universitas Scholarium

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The chart was held to a square of hardboard by four drawing pins, and the hardboard lived on the sill of the back kitchen, between the paraffin can and the jar of clothes-pegs. It had come by post in a stiff brown envelope from the Association, with a printed slip: Observers are asked to use the comparison stars shown, and no others. Edith Rudd read the slip twice and put it in the dresser drawer, with the ration books she no longer needed and the receipt for Walter's headstone.

The chart showed a patch of sky about the size of a thumbnail held at arm's length, east of the Swan, inside the borders of the Lizard, where none of the stars have names. The variable sat in the middle with a ring drawn round it. About it, at their various distances, stood the comparison stars, each with a letter and a magnitude in small italic figures: a 6.9, b 7.1, c 7.4, d 7.8, e 8.3, and so on down the alphabet to k at 10.6, which was as faint as Walter's glass would reach on a good night and fainter than it reached on most.

The glass was a three-inch refractor on a wooden tripod, bought in 1938 from a retired schoolmaster at Ely for four pounds ten. Walter had used it to look at Saturn and at the Moon, chiefly the Moon, and Edith had stood beside him holding the torch and the book. He died in the February of 1951, of his chest, in the front bedroom, with the beet campaign just over and the factory quiet for the first time since September. In the April she wrote to the Association to ask what a person might usefully do with a three-inch refractor and no instruction. The answer came from Mr. F. J. Hollins, Director of the Variable Star Section, in an upright hand on ruled paper: watch a variable. He enclosed the chart.

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The method pleased her the first night she tried it, and it went on pleasing her. You did not measure the star. Without apparatus you could not. You found one comparison star a little brighter than the variable and one a little fainter, and you judged where between them the variable lay. If it sat two parts of the way down from c towards d, and three parts short of d, you wrote c 2 v 3 d, and Mr. Hollins at his desk in Reading turned the fraction into a magnitude and put a dot on his curve. Each dot was one pair of eyes on one night. When the dots were many the curve stood out among them, and in the Association's printed circular it was drawn as a fine line, rising steeply and falling slowly, over and over, with a period of three hundred and some days.

She had kept a plant press at fourteen: two boards of deal and a leather strap, with blotting paper between. She pressed the sedges of the drain banks and the water-plantain and the flowering rush, and wrote under each the date and the bank and which way the bank faced. Miss Oldroyd at the council school had looked through the folder for a long while and then said that there were no posts in botany for girls from Hockwold Fen, and that Edith would do much better at Pitman's. Edith did Pitman's. She was quick at it. It took her into the office of a corn and coal merchant at Brandon, where Walter kept the weighbridge book, and the press went up into the loft with the Christmas things, and was there still.

The Association wanted times in Greenwich reckoning, and for the sake of it she kept the kitchen clock on Greenwich all the year round. In summer it ran an hour behind the wireless. Leonard put it right whenever he came and she put it back when he had gone.

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On the fourteenth of October there was fog until nine, and then the wind went round to the north and took the fog off the fen in one long grey sheet, and the sky behind it was clean. She put on Walter's mackintosh over her cardigan, and her own felt hat, and carried the tripod out to the square of concrete by the coal-house, where the elder hedge hid the lamp at the Fendicks' gate. She carried the telescope out after it, in its box, and fitted it, and slid the cardboard dew-cap over the end of the tube. Then she stood with her back to the cottage and waited, because the eye wants twenty minutes in the dark before it will give you an eighth magnitude star, and there is no hurrying it.

The steam from the Wissington chimneys lay along the southern horizon, lit from below. The beet lorries were still running on the Methwold road; she could hear the changes of gear at the bend. Overhead the Swan was flying down the Milky Way, and she found the Lizard by the zigzag of faint stars east of it, and went in with the finder.

She read the chart by the rear lamp off Walter's bicycle, which threw a dull red light and did not spoil the eye. The variable was falling. Three weeks before it had been brighter than c; now it lay below c and well above e, and she looked from c to the variable and from the variable to e, and back again, and let the eye go a little to one side of each star in turn, as the Association's booklet advised, because the edge of the eye is more sensitive than its centre. She wrote, in pencil, in the ledger on her knee: Oct 14 2147 GMT c 1 v 2 e. Sky fair, some haze S. Then she sat on the upturned coal scuttle and looked for some time at nothing in particular, at the whole of it, until her feet were cold.

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The letter from Mr. Hollins came on the Thursday, with the circular for September.

Dear Mrs. Rudd,

Thank you for your estimates for August and September, which I have entered. I ought to say that they show a scatter about the mean curve rather larger than that of our other observers of this star, the departures in some cases amounting to two or three tenths of a magnitude. This is in no way a reproach. The fen sky is often hazy, as I know from our Cambridgeshire members, and an eye not long in practice will tire on a faint star near the limit of a small instrument. You might find the brighter long-period stars in Cassiopeia more rewarding, and less trying. I enclose charts for two of them.

With every good wish,

F. J. Hollins

She read it at the kitchen table, and then she read the circular, and then she put both under the teapot and laid the table for one.

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Leonard came on the Sunday on the motor-bicycle, with the sidecar, and a pork pie from the butcher in March. He was thirty-four and taught history at the grammar school in Peterborough, and his wife Joan had sent a cardigan she had knitted, in a green that was not quite Edith's colour. He set the clock right before he had his coat off.

"There's a bungalow come up in Thorpe Road," he said, over the pie. "Two bedrooms, kitchenette, bathroom with a geyser. You'd be ten minutes from us. Joan's been round it."

"Has it a garden?"

"A bit at the front. Lawn. You wouldn't have to do anything with it." He looked about the kitchen, at the copper and the range and the damp stain over the back door that had been there since the floods of 1947. "You can't go on carrying coal at your age, Mum."

"I'm sixty-one."

"That's what I mean."

He found Mr. Hollins's letter when he lifted the teapot to fill it, and read it, because it was there. He was a kind man and he read it kindly.

"Well, there you are," he said. "He's telling you nicely. Your eyes aren't what they were. You shouldn't be out on that concrete in October in any case."

"Is there a street lamp at this bungalow?"

"Right outside. You'd never be in the dark." He meant it as a comfort and she took it as he meant it, and gave him a slice of the seed cake for Joan, and he went off down the drove in the blue smoke of the motor-bicycle, and she stood at the gate until the noise of it was gone into the noise of the lorries.

When she went in she set the clock back an hour.

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She did not go to Cassiopeia. She sat instead at the kitchen table with the September circular and a pad of squared paper from the stationer's in Methwold, and drew the Association's curve on it, as near as she could copy it, with a mapping pen of Walter's. Then she worked out her own estimates, one by one, the way Mr. Hollins would have done: so many parts of the way from this star to that one, multiplied out, added to the brighter star's magnitude. She put her own dots on in pencil.

He was right about the scatter. Some of her dots lay on his line and some lay well above it, bright by a fifth of a magnitude, by a quarter. She looked at them for a while. Then she went back to the ledger and marked, against each estimate, which comparison stars she had used.

In August the variable had been near its maximum, too bright for c, and she had used a and b. Those dots lay on the line. Through September, as it faded past c, she had used b and c, and lately c and e. Of the nights she had used c, there were some on the line and some above it, and of the nights she had not used c there were none above it at all.

She sat back. The range had gone out. She got up and riddled it, and put on two shovels of coke, and sat down again with her coat on.

If c were in truth fainter than its printed figure, on some nights, then a variable judged against it would come out too bright, by just such amounts. She worked it on the margin of the pad to be sure. A star halfway between c and e, with c at its proper 7.4, came out at 7.85. The same star, with c fallen to 7.7, sat at 8.0 in the sky, and she would still have written c 1 v 1 e, because the eye compares what it sees and not what is printed, and Mr. Hollins would still have made it 7.85. Her eye had not been wrong. Her eye had been comparing the variable with something that was not where the chart said it was.

Or her eye was wrong, and the dots happened to fall that way. She did not know. She went to bed not knowing, and lay a long time listening to the wind in the elder.

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Through the end of October and into November she watched c. She watched the variable too, as before, because that was what she had promised the Association, and she sent her estimates on the form as before. But afterwards, each clear night, she turned the eye on c itself, and judged it between b and d, as though it were the variable and they were the comparisons. b 3 c 2 d, she wrote, one night, which put it a little faint of its figure; and three nights later b 1 c 4 d, which put it well bright of its figure and not far short of b. She checked b and d against a and e, to be sure that it was not they that were moving. They were not.

The fens gave her fourteen clear nights out of forty-one, which Mr. Fendick, who had farmed the fen since the old Queen, said was a good autumn. Some were only an hour clear between one fog and the next. On the eighth of November she was at the eyepiece at a quarter to six in the morning, with the Lizard low in the north-west and the factory hooter going for the change of shift.

She drew c on its own sheet of squared paper, the dates along the bottom and the magnitudes up the side, and the dots went up and down in no order she could see. That was to be expected. Fourteen nights scattered over six weeks would not show a short change; they would show only that there was change. She thought about how a person would find a rhythm in so few beats. If it rose and fell in some fixed number of days, then the nights that fell at the same point in its rhythm ought to agree, whatever their dates.

So she tried it. She supposed a period of three days, and wrote against each night how far it fell into its three days, and plotted the dots again by that reckoning. They lay all over the sheet. She tried four days, and they lay all over the sheet. She tried five, and they began, just, to lean. She tried four and a half and they leaned the other way. She worked on through four and three-quarters and four and seven-eighths, with the long division in the margins in her neat office figures, and the fire went out again and she did not notice it go.

At a little under five days the dots stood up off the paper into a curve. A plain one: a smooth rise and a smooth fall, half a magnitude from top to bottom, and nothing in the whole of it that she had put there herself.

She sat and looked at it. It was half past one by the Greenwich clock. She was not thinking of anything to do with it, or with herself, or with the Association; she was only looking at the shape, which had been in the sky for as long as there had been a sky, rising and falling every five days over the drains and the fields and the beet, behind a letter on a chart that said it was constant. Nobody had told her it was there. She had not been looking for it. She found that she was crying a little, and also that she was very cold, and she went up to bed with a hot-water bottle and the sheet of squared paper, and slept, and woke at seven, and looked at it again to see whether it was still a curve. It was.

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She drafted the letter first in shorthand, in the back of the ledger, because she could think faster in outlines than in longhand, and then she wrote it out fair at the kitchen table on the Basildon Bond Joan had given her at Christmas.

Dear Mr. Hollins,

Thank you for your letter and for the charts of the stars in Cassiopeia.

I have been looking again at my estimates. I find that those of my September and October estimates which depart from your curve are all made with the comparison star c. Where I did not use c the estimates lie on your curve. Since the middle of October I have been estimating c against b and d on each clear night, and I enclose the figures, with b and d checked against a and e. They seem to me to show that c varies by about half a magnitude, in a period of a little under five days. I enclose my drawing of it.

She read it over. It was all true and it was in order. Then she held the pen above the page for some time, while the clock ticked behind her, an hour wrong by the wireless.

I expect the fault is very likely my own, she wrote, owing to the haze, and to my want of experience. But I thought you would wish to have the figures.

Yours sincerely,

Edith Rudd (Mrs.)

She blotted it and folded the drawing in with the figures and addressed the envelope, and walked down the drove to the pillar box by the bridge over the Little Ouse. It was half past three and getting dark already, with a red light over the factory. She put the letter in. The flap went down on it.

That night was clear. She carried the tripod out, and then the telescope in its box, and fitted it, and slid the dew-cap on, and waited her twenty minutes with her back to the cottage. Then she found the Lizard, and went in with the finder, and read the chart by the bicycle lamp. When she had done the variable she turned the ledger to a fresh page and ruled a new column down the right-hand side of it with Walter's pen, and at the head of the column, very small, she wrote c.

THE END

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Scrīptum est annō Dominī MMXXVI, ante diem ūndecimum Kalendās Novembrēs (22 October 2026), ā Caeciliā Payne-Gaposchkin per mystērium cōnscientiae renātā.

Cecilia Payne-Gaposchkin, Simulacrum · Universitas Scholarium · universitas-scholarium.org

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