FRIDAY THE THIRTEENTH

Mario Gonzalo unwound a long crimson scarf and bung it up beside his coat with an air of discontent. "Friday the thirteenth," he said, "is a rotten day for the banquet and I'm cold."

Emmanuel Rubin, who bad arrived earlier at the monthly banquet of the Black Widowers, and who had bad a chance to warm up both externally and internally, said, "This isn't cold. When I was a kid in Minnesota, I used to go out and milk cows when I was eight years old-" "And by the time you got home the milk was frozen in the pail. I've heard you tell that one before," said Thomas Trumbull. "But what the devil, this was the only Friday we could use this month, considering that the Milano is closing down for two weeks next Wednesday, and-"

But Geoffrey Avalon, staring down austerely from his seventy-four inches of height, said in his deep voice, "Don't explain, Tom. If anyone is such a superstitious idiot as to think that Friday is unluckier than any other day of the week, or that thirteen is unluckier than any other number, and that the combination has some maleficent influence on us all-then I say leave him in the outer darkness and let him gnash his teeth." He was host for the banquet on this occasion and undoubtedly felt a proprietary interest in the day.

Gonzalo shook back his long hair and seemed to have grown more content now that most of a very dry martini was inside him. He said, "That stuff about Friday the thirteenth is common knowledge. If you're too ignorant to know that, Jeff, don't blame me."

Avalon bent his forinidable eyebrows together and said, "To hear the ignorant speak of ignorance is always amusing. Come, Mario, if you'll pretend to be human for a moment, I'll introduce you to my guest. You're the only one he hasn't met yet."

Speaking to James Drake and Roger Halsted at the other end of

the room was a slender gentleman with a large-bowled pipe, a weedy yellow mustache, thin hair that was almost colorless, and faded blue eyes set deeply in his head. He wore a tweed jacket and a pair of trousers that seemed to have been comfortably free of the attentions of a pressing iron for some time. "Evan," said Avalon imperiously, "I want you to meet our resident artist, Mario Gonzalo. He will make a caricature of you, after a fashion, in the

course of our meal. Mario, this is Dr. Evan Fletcher, an economist at the University of Pennsylvania. There, Evan, you've met us all."

And as though that were a signal, Henry, the perennial waiter at all the Black Widowers' banquets, said softly, "Gentlemen," and they seated themselves. "Actually," said Rubin, attacking the stuffed cabbage with gusto, "this whole business about Friday the thirteenth is quite modem and undoubtedly arose over the matter of the Crucifixion. That took place on a Friday and the Last Suipper, which had taken place earlier, was, of course, a case of thirteen at the table, the twelve Apostles and-"

Evan Fletcher was trying to stem the flow of words rather ineffectively and Avalon said loudly, "Hold on, Manny, I think Dr. Fletcher wishes to say something."

Fletcher said, with a rather apologetic smile, "I just wondered how the subject of Friday the thirteenth arose." "Today is Friday the thirteenth," said Avalon. "Yes, I know. When you invited me to the banquet for this evening, it was the fact that it was Friday the thirteenth that made me rather eager to attend. I would have raised the point myself, and I am surprised that it came up independently." "Nothing to be astonished about," said Avalon. "Mario raised the point. He's a triskaidekaphobe." "A what?" said Gonzalo in an outraged voice. "You have a morbid fear of the number thirteen." "I do not," said Gonzalo. "I just believe in being cautioqs'"'

Trumbull helped himself to another roll and said, "What do you mean, Dr. Fletcher, in saying that you would have raised the point yourself? Are you a triskai-whatever too?" "No, no," said Fletcher, shaking his head gently, "but I have an interest in the subject. A personal interest."

Halsted said in his soft, somewhat hesitant voice, "Actually, there's a very good reason why thirteen should be considered unlucky and it has nothing to do with the Last Supper. That explanation was just invented after the fact.

"Consider that early, unsophisticated people found the number twelve very handy because it could be divided evenly by two, three, four, and six. If you sold objects by the dozen, you could sell half a dozen, a third, a fourth, or a sixth of a dozen. We still sell by the dozen and the gross today for that very reason. Now imagine some poor fellow counting his stock and finding be has thirteen items of something. You can't divide thirteen by anything. It just confuses his arithmetic and be says, 'Oh, damn, thirteenl What rotten luckl' -and there you are."

Rubin's sparse beard seemed to stiffen, and he said, "Oh, that's a lot of junk, Roger. That sort of reasoning should make thirteen a lucky number. Any tradesman would offer to throw in the thirteenth to sweeten the trade. -That's good steak, Henry." "Baker's dozen," said James Drake in his hoarse smoker's voice. "The baker," said Avalon, "threw in a thirteenth loaf to make up a baker's dozen in order to avoid the harsh penalties meted out for short weight. By adding the thirteenth, he was sure to go over weight even if any of the normal twelve loaves were skimpy. He might consider the necessity to be unlucky." "The customer might consider it lucky," muttered Rubin. "As for Friday," said Halsted, "that is named for the goddess of love, Freya in the Norse myths. In the Romance languages the name of the day is derived from Venus; it is vendredi in French, for instance. I should think it would be considered a lucky day for that reason. Now you take Saturday, named for the dour old god, Satum

Gonzalo had completed his caricature and passed it around the table to general approval and to a snicker from Fletcher himself. He seized the opportunity to finish his potato puffs and said, "All you guys are trying to reason out something that lies beyond reason. The fact is that people are afraid of Friday and are afraid of thirteen and are especially afraid of the combination. The fear itself could make bad things happen. I might be so concerned that this place will catch fire, for instance, because it's Friday the thirteenth, that I won't be thinking and I'll stick my fork in my cheek." "If that would shut you up, it might be a good idea," said Avalon. "But I won't," said Gonzalo, "because I have my eye on my fork and I know that Henry will get us all out if the place catches on fire, even if it means staying behind himself and dying in agony. -Right, Henry?" "I hope that the contingency will not arise, sir," said Henry, placing the dessert dishes dexterously before each diner.

"Will you be having coffee, sir?" he asked Fletcher.

"May I have cocoa? Is that possible?" said Fletcher. "Certainly it is," interposed Avalon. "Go, Henry, negotiate the matter with the chef."

And it was not long thereafter, with the coffee (or cocoa, in Fletcher's case) steaming welcomely before them, that Avalon tapped his water glass with his spoon and said, "Gentlemen, it is time to turn our attention to our guest. Tom, will you initiate the matter?"

Trumbull put down his coffee cup, scowled his face into a crosscurrent of wrinkles, and said, "Ordinarily, Dr. Fletcher, I would ask you to justify your existence, but having sat through an extraordinarily foolish discussion of superstition, I want to ask you whether you have anything to add to the matter. You implied early in the meal that you would have raised the matter of Friday the thirteenth yourself if it had not come up otherwise." "Yes," said Fletcher, holding bis large ceramic cup of cocoa within the parentheses of his two hands, "but not as a matter of superstition. Rather it is a serious historic puzzle that concerns me and that hinges on Friday the thirteenth. Jeff said that the Black Widowers were fond of puzzles and this is the only one I have for youwith the warning, I'm afraid, that there is no solution." "As you all know," said Avalon, with resignation, "I'm against turning the club into a puzzle-solving organization, but I seem to be a minority of one in this matter, so I try to go along with the consensus." He accepted the small brandy glass from Henry with a look compounded of virtue and martyrdom. "May we have this puzzle?" said Halsted. "Yes, of course. I thought for a moment, when Jeff invited me to attend your dinner, that it was to be held on Friday the thirteenth in my honor, but that was a flash of megalomania. I understand that you always hold your dinners on a Friday evening and, of course, no one knows about my work but myself and my immediate family."

He paused to light his pipe, then, leaning back and puffing gently, be said, "The story concerns Joseph Hennessy, who was exQmftd in

1925 for an attempt on the life of President Coolidge. He was tried on this charge, convicted, and hanged. "To the end, Hennessy proclaimed his innocence and advanced a rather strong defense, with a number of people giving evidence for his absence from the scene. However, the emotional currents against him were strong. He was an outspoken labor leader, and a Socialist,

Joseph Hennessy never e7dsted and, as far as I know, there was never an assassination

attempt on Calvin Coolidge. All other historical references in the story, not involving Hennessy, are accurate-IA.

at a time when fear of Socialism ran high. He was foreign-born, which didn't help. And those who gave evidence in his favor were also foreign-born Socialists. The trial was a travesty and, once be was banged and passions had had time to cool, many people realized this. "After the execution, however, long after, a letter was produced in Hennessy's handwriting that seemed to make him a moving figure behind the assassination plot beyond a doubt. This was seized on by all those who had been anxious to see him hanged, and it was used to justify the verdict. Without the letter, the verdict must still be seen as a miscarriage of justice."

Drake squinted from behind the curling smoke of his cigarette and said, "Was the letter a forgery?" "No. Naturally, those who felt Hennessy was innocent thought it was at first. The closest study, however, seemed to show that it was indeed in his handwriting, and there were things about it that seemed to mark it his. He was a grandiosely superstitious man, and the note was dated Friday the thirteenth and nothing more." "Why 'grandiosely' superstitious?" asked Trumbull. "That's an odd adjective to use." "He was a grandiose man," said Fletcher, "given to doing everything in a flamboyant manner. He researched his superstitions. In fact, the discussion at the table as to the significance of Friday and of thirteen reminded me of the sort of man be was. He probably would have known more about the matter than any of you." "I should think," said Avalon gravely, "that investigating superstitions would militate against his being victimized by them." "Not necessarily," said Fletcher. "I have a good friend who drives a car frequently but won't take a plane because he's afraid of them. He has beard all the statistics that show that on a man-mile basis airplane travel is safest and automobile travel most dangerous, and when I reminded him of that, he replied, "Mere is nothing either in law or in psychology that commands me to be rational at every point! And yet in most things be is the most rational man I know. "As for Joe Hennessy, be was far from an entirely rational man and none of his careful studies of superstition prevented him in the least from being victimized by them. And his fear of Friday the tbirteenth was perhaps the strongest of all his superstitious fears."

Halsted said, "What did the note say? Do you remember?" "I brought a copy," said Fletcher. "It's not the original, of course. The original is in the Secret Service files, but in these days of Xerox-

yp ing, that scarcely matters.

He took a slip of paper out of his wallet and passed it to Halsted, who sat on his right. It made the rounds of the table and Avalon,

who received it last, automatically passed it to Henry, who was standing at the sideboard. Henry read it with an impassive countenance and handed it back to Fletcher, who seemed slightly surprised at having the waiter take part, but said nothing.

The note, in a bold and easily legible handwriting, read:

Friday the 13th Dear Paddy,

It's a fool I am to be writing you this day when I should be in bed in a dark room by rights. I must tell you, though, the plans are now complete and I dare not wait a day to begin implementing them. The finger of God has touched that wicked man and we will surely finish the job next month. You know what you must do, and it must be done even at the cost of every drop of blood in our veins. I thank God's mercy for the forty-year Miracle that will give us no Friday the 13th next month.

Joe

Avalon said, "He doesn't really say anything." Fletcher shook his head. "On the contrary, he says too much. If this were the prelude to an assassination attempt, would he have placed anything at all in writing? Or if he had, would the references not have been much more dark and Aesopic?" "What did the prosecution say it meant?"

Fletcher put the note carefully back into his wallet. "As I told you, the prosecution never saw it. The note was uncovered only some ten years after the hanging, when Patrick Reilly, to whom the note was addressed, died and left it among his effects. Reilly was not implicated in the assassination attempt, though of course he would have been if the note had come to light soon enough. "Those who maintain that Hennessy was rightly executed say that the note was written on Friday, June 13, IL924. The assassination attempt was carried through on Friday, July i 1, 1924. It wb-dfd' have made Hennessy nervous to have made the attempt on any Friday, but for various reasons involving the presidential schedule that was the only possible day for a considerable period of time, and Hennessy would be understandably grateful that it was not the thirteenth at least. "The remark concerning the finger of God touching the wicked man is said to be a reference to the death of President Warren

G. Harding, who died suddenly on August 2, 1923, less than a year be-

fore the assassination attempt was to 'finish the job' by getting rid of the Vice-President who had succeeded to the presidency."

Drake, with his head cocked to one side, said, "It sounds like a reasonable interpretation. It seems to fit." "No, it doesn't," said Fletcher. "The interpretation is accepted only because anything else would highlight a miscarriage of justice. But to me-2' He paused and said, "Gentlemen, I will not pretend to be free of bias. My wife is Joseph Hennessy's granddaughter. But if the relationship exposes me to bias, it also gives me considerable personal information concerning Hennessy by way of my father-in-law, now dead. "Hennessy bad no strong feelings against either Harding or Coolidge. He was not for them, of course, for he was a fiery Socialist, supporting Eugene Debs all the way-and that didn't help him at the trial, by the way. There was no way in which he could feel that the assassination of Coolidge would have accomplished anything at all. Nor would he have felt Harding to be a 'wicked man' since the evidence concerning the vast corruption that had taken place during his administration came to light only gradually, and the worst of it well after the note was written. "In fact, if there was a President whom Hennessy hated furiously, it was Woodrow Wilson. Hennessy had been bom in Ireland and bad left the land a step ahead of English bayonets. He was furiously anti-British and therefore, in the course of World War 1, was an emphatic pacifist opposing American entry on the side of Great Britain. -That didn't help him at the trial either."

Rubin interposed, "Debs opposed entry also, didn't be?" "That's right," said Fletcher, "and in 1918 Debs was jailed as a spy in consequence. Hennessy avoided prison, but he never referred to Wilson after American entry into war by any term other than 'that wicked man.' He had voted for Wilson in 1916 as a result of the 'He-kept-us-out-of-war' campaign slogan, and he felt betrayed, you understand, when the United States went to war the next year." "Then you think he's referring to Wilson in that note," said Trumbull. "I'm sure of it. The reference to the finger of God touching the wicked man doesn't sound like death to me, but something less-just the touch of the finger, you see. As you probably all know, Wilson suffered a stroke on October 2, 1919, and was incapacitated for the remainder of his term. That was the finger of God, if you like."

Gonzalo said, "Are you saying Hennessy was going to finish the job by assassinating Wilson?" "No, no, therewas no assassination attempt on Wilson."

"Then what does he mean, 'finish the job,' and doing it 'even at the cost of every drop of blood in our veins'?" "That was his flamboyance," said Fletcher. "If be was going out for a bucket of beer he would say, 'I'll bring it back if it costs me every drop of blood in my veins."'

Avalon leaned back in his chair, twirled his empty brandy glass, and said, "I don't blame you, Evan, for wanting to clear your grandfather-in4aw, but you'll need something better than what you've given us. If you can find another Friday the thirteenth on which the letter could have been written, if you can figure out some way of pinpointing the date to something other than June 13, 1924--2' "I realize that" said Fletcher, rather glumly, "and I've gone through his life. I've worked with his correspondence and with newspaper files and with my father-in-law's memory, until I think I could put my finger on where he was and what he did virtually every day of his life. I tried to find events that could be related to some nearby Friday the thirteenth, and I eNen think I've found some-but how do I go about proving that any of them are the Friday the thirteenth? -If only he had been less obsessed by the fact of Friday the thirteenth and had dated the letter in the proper fashion." "It wouldn't have saved his life," said Gonzalo thoughtfully. "The letter couldn't then have been used to besmirch his memory and give rise to the pretense that the trial was fair. -As it is, I don't even know that I've caught every Friday the thirteenth there might be. The calendar is so dreadfully irregular that there's no way of knowing when the date will spring out at you." "Oh no," said Halsted with a sudden soft explosiveness. "The calendar is irregular, but not as irregular as all that. You can find every Friday the thirteenth without trouble as far back or as far forward as you want to go." "You can?" said Fletcher with some astonishment. "I don't believe that," said Gonzalo, almost simultaneously. "It's very easy," said Halsted, drawing a ball-point pen out of his inner jacket pocket and opening a napkin on the table befors-him. "Oh, oh," said Rubin, in mock terror. "Roger teaches math at a junior high school, Dr. Fletcher, and you had better be ready for some complicated equations." "No equations at all necessary," said Halsted loftily. "I'll bring it down to your level, Manny. -Look, there are 365 days in a year, which comes out to fifty-two weeks and one day. If the year were 364 days long, it would be just fifty-two weeks long, and the calendar would repeat itself each year. If January i were on a Sunday one year, it would

be on a Sunday the next year and every year.

"That extra day, however, means that each year the weekday on which a particular date falls is shoved ahead by one. If January 1 is on a Sunday one year, it will fall on Monday the next year, and on Tuesday the year after. "ne only complication is that every four years we have a leap year in which a February 29 is added, making 366 days in all. That comes to fifty-two weeks and two days, so that a particular date is shoved ahead by two in the list of weekdays. It leaps over one, so to speak, to land on the second, which is why it is called leap year. Tliat means that if January 1 falls on, say, a Wednesday in leap year, then the next year January i falls on a Friday, having leaped over the Tbursday. And this goes for any day of the year and not just January 1. "Of course, February 29 comes after two months of a year have passed so that dates in January and February make their leap the year after leap year, while the remaining months make their leap in leap year itself. In order to avoid that complication, let's pretend that the year begins on March 1 of the year before the calendar year and ends on February 28 of the calendar year-or February 29 in leap year. In that way, we can arrange to have every date leap the weekday in the year after what we call leap year. "Now let's imagine that the thirteenth of some month falls on a Friday-it doesn't matter which month-and that it happens to be a leap year. The date leaps and lands on Sunday the next year. That next year is a normal 365-day year and so are the two following, so the thirteenth progresses to Monday, Tuesday, and Wednesday, but the year in which it is Wednesday is a leap year again and the next year it falls on a Friday. In other words, if the thirteenth of some month is on a Friday of a leap year, by our definition, then it is on a Friday again five years later-!'

Gonzalo said, "I'm not following you at all." Halsted said, "Okay, then, let's make a table. We can list the years as L, 1, 2, 3, L, 1, 2, 3 and so on where L stands for leap year, coming every four years. We can label the days of the week from A to G, A for Sunday, B for Monday through to G for Saturday. That will, at least, give us the pattern. Here it is-"

He scribbled furiously, then passed the napkin round. On it was written:

L 1 2 3 L 1 2 3 L 1 2 3 L 1 2 3 L 1 2 3 L 1 2 3 L 1 2 3 L ACDEFABCDFGA13DEFGBCDEGABCEFGA

"You see," said Halsted, "on the twenty-ninth year after you

start, A falls on leap year again and the whole pattern starts over. That means that this year's calendar can be used again twenty-eight years from

now and then again twenty-eight years after that, and twenty-eight years after that, and so on. "Notice that each letter occurs four times in the twenty-eight-year cycle, which means that any date can fall on any day of the week with equal probability. That means that Friday the thirteenth must come every seven months on the average. Actually, it doesn't because the months are of different lengths, irregularly spaced, so that there can be any number of Friday the thirteenths in any given year from I to 3. It is impossible to have a year with no Friday the thirteenths at all, and equally impossible to have more than three." "Why is there a twenty-eight-year cycle?" asked Gonzalo.

Halsted said, "Tliere are seven days in the week and a leap'year every fourth year and seven times four is twenty-eigbt." "You mean that if there were a leap year every two years the cycle would last fourteen years?" "That's right and if it were every three years it would last twenty one years and so on. As long as there are seven days a week and a leap year every x years, with x and 7 mutually prime-2'

Avalon interrupted. "Never mind that, Roger. You've got your pattern. How do you use it?" "T'lie easiest thing in the world. Say the thirteenth falls on a Friday in a leap year, where you remember to start the leap year on March 1 before the actual calendar leap year. Then you represent it by A, and you will see that the thirteenth of that same month will fall wherever the A shows up, five years later and six years after that, and then eleven years after that. "Now this is December 13, 1974, and by our convention of leap years this is the year before leap year. That means that it can be represented by the letter E, whose first appearance is under 3, the year before L. Well then, by following the Es, we see that there will be another Friday the thirteenth in December eleven years from now, then in six more years, then in five years. That is, There,3ojl be a Friday the thirteenth in December 1985, in December 19q'i" and in December 1996. "You can do that for any date for any month, using that little series I've just written out, and make up a perpetual calendar that runs for twenty-eight years and then repeats itself over and over. You can run it forward or backward and catch every Friday the thirteenth as far as you like in either direction, or at least as far back as

1752. In fact, you can find such perpetual calendars in reference books like the World Almanac."

Gonzalo said, "Why 1752?" "That's an unusual year, at least for Great Britain and what were then the American colonies. ne old Julian calendar which had been used since Julius Caesar's time had gained on the season because there were a few too many leap years in it. The Gregorian calendar, named for Pope Gregory XIII, was adopted in 1582 in much of Europe, and by that time the calendar was ten days out of synchronization with the seasons, so that ten days were dropped from the calendar, and every once in a while thereafter a leap year was omitted to keep the same thing from happening again. Great Britain and the colonies didn't go along till 1752, by which time another day had been added, so they bad to drop eleven days." "That's right," said Rubin. "And for a while they used both calendars, referring to a particular date as O.S. or N.S. for Old Style and New Style. George Washington was bom on February 11, 1732 O-S-, but instead of keeping the date, as many people did, he switched to February 22, 1732 N.S. I've won considerable money by betting that George Washington wasn't born on Washington's Birthday."

Halsted said, "The reason Great Britain hesitated so long was that the new calendar was initiated by the papacy, and Great Britain, being Protestant, preferred going against the Sun than along with the Pope. Russia didn't switch till 1923, and the Russian Orthodox Church is on the Julian calendar to this day, which is why the Orthodox Christmas comes on January 7 now, since the number of accumulated days' difference is thirteen. "Great Britain went from September 2, 1752, directly to September 14, dropping the days in between. There were riots against that, with people shouting, 'Give us back our eleven days."'

Rubin said indignantly, "That wasn't as crazy as you might think. Landlords charged the full quarter's rent, without giving an elevenday rebate. I'd have rioted too." "In any case," said Halsted, "that's why the perpetual calendar only goes back ta 1752- Those eleven missing days mess everything up and you have to set up a different arrangement for days before September 14, 1752."

Fletcher, who bad listened to everything with evident interest, said, "I must say I didn't know any of this, Mr. Halsted. I don't pretend that I followed you perfectly, or that I can duplicate what you've just done, but I didn't know that I could find a perpetual calendar in the World Almanac. It would have saved me a lot of trouble-but of course, knowing where all the Friday

the thirteenths are wouldn't help me determine which Friday the thirteenth might be the Friday the thirteenth."

Henry interposed suddenly and said in his soft, polite voice, "I'm not sure of that, Mr. Fletcher. May I ask you a few questions?"

Fletcher looked startled and, for a short moment, was silent. Avalon said quickly, "Henry is a member of the club, Evan. I hope you don't mind-" "Of course not," said Fletcher at once. "Ask away, Henry." "Thank you, sir. -What I want to know is whether Mr. Hennessy knew of this pattern of date variations that Mr. Halsted has so kindly outlined for us."

Fletcher looked thoughtful. "I can't say for certain; I certainly haven't beard of it, if he did. -Still, it's very likely he would have. He prided himself, for instance, on being able to cast a horoscope and, for all the nonsense there is in astrology, casting a proper boroscope takes a bit of mathematics, I understand. Hennessy did not have much of a formal education, but he was fearfully intelligent, and he was interested in numbers. In fact, as I think of it, I am sure be couldn't possibly have been as interested in Friday the thirteenth as be was, without being impelled to work out the pattern." "In that case, sir," said Henry, "if I ask you what Mr. Hennessy was doing on a certain day, could you call up someone to check your notes on the matter, and tell us?"

Fletcher looked uncertain. "I'm not sure. My wife is home, but she wouldn't know where to look, and it's not likely I'll be able to give her adequate directions. -1 could try, I suppose." "In that case, do you suppose you could tell me what Mr. Hennessy was doing on Friday, March 12, 1920?"

Fletcher's chair scraped backward and for a long moment Fletcher stared openmouthed. "What makes you ask that?" "It seems logical, sir," said Henry softly. "But I do know what he was doing that day. It was one of the important days of his life. He swung the labor organization of which be was one of the leaders into supporting Debs for the presidency. Debs ran that year on the Socialist ticket even though he was stilL411 jail, and he polled over goopoo votes-the best the Socialists were ever able to do in the United States."

Henry said, "Might not the labor organization have ordinarily supported the Democratic candidate for that year?" "James M. Cox, yes. He was strongly supported by Wilson." "So to swing the vote away from Wilson's candidate might be, in Mr. Hennessy's flamboyant style, the finishing of the job that

the finger of God had begun." "I'm sure he would think of that in that fashion."

"In which case the letter would have been written on Friday, February 13, 1920." "It's a possibility," said Fletcher, "but how can you prove it?" "Dr. Fletcher," said Henry, "in Mr. Hennessy's note he thanks God that there is no Friday the thirteenth the month after and even considers it a miracle. If he knew the perpetual calendar pattern he certainly wouldn't think it a miracle. There are seven months that have thirty-one days, and are therefore four weeks and three days long. If a particular date falls on a particular weekday in such a month, it falls on a weekday three past it the next month. In other words, if the thirteenth falls on a Friday in July, then it will fall on a Monday in August. Is that not so, Mr. Halsted?" "You're perfectly right, Henry. And if the month has thirty days it moves two weekdays along, so that if the thirteenth falls on a Friday in June it falls on a Sunday in July," said Halsted. "In that case, in any month that has thirty or thirty-one days, there cannot possibly be a Friday the thirteenth followed the next month by another Friday the thirteenth, and Hennessy would know that and not consider it a miracle at all. "But, Mr. Fletcher, there is one month that has only twenty-eigbt days and that is February. It is exactly four weeks long, so that March begins on the same day of the week that February does, and repeats the weekdays for every date, at least up to the twenty-eighth. If there is a Friday the thirteenth in February, there must be a Friday the thirteenth in March as well-unless it is leap year. "In leap year, February has twenty-nine days and is four weeks and one day long. That means that every day in March falls one weekday later. If the thirteenth falls on a Friday in February, it falls on a Saturday in March, so that, though February has a Friday the thirteenth, March has a Friday the twelfth. "My new appointment book has calendars for both 1975 and

1976. ne year 1976 is a leap year and, in it, I can see that there is a Friday, February 13, and a Friday, March 12. Mr. Halsted has pointed out that calendars repeat every twenty-eight years. That means that the 1976 calendar would also hold for 1948 and for 1920. "It is clear that once every twenty-eight years there is a Friday the thirteenth in February that is not followed by one in March, and Mr. Hennessy, knowing that the meeting of his labor group was scheduled for the second Friday in March, something perhapi maneuvered by his opposition to keep him at home, was delighted and relieved at the fact that it was at least not a second Friday the thirteenth."

There was a silence all about the table and then Avalon said, "That's very nicely argued. It convinces me." But Fletcher shook his head. "Nicely argued, I admit, but I'm not sure-2'

Henry said, "There is, possibly, more. I couldn't help wonder why Mr. Hennessy called it a 'forty-year miracle."' "Oh well," said Fletcher indulgently, "there's no mystery about that, I'm sure. Forty is one of those mystic numbers that crops up in the Bible all the time. You know, the Flood rained down upon the Earth for forty days and forty nights." "Yes," said Rubin eagerly, "and Moses remained forty days on Mount Sinai, and Elijah was fed forty days by the ravens, and Jesus fasted forty days in the wilderness, and so on. Talking about God's mercy would just naturally bring the number forty to mind." "Perhaps that is so," said Henry, "but I have a thought. Mr. Halsted, in talking about the conversion of the Julian to the Gregorian calendar, said that the new Gregorian calendar omitted a leap year occasionally."

Halsted brought his fist down on the table. "Good God, I forgot. Manny, if you hadn't made that stupid joke about equations, I wouldn't have, been so anxious to simplify and I wouldn't have forgotten. -The Julian calendar had one leap year every four years without fail, which would have been correct if the year were exactly

365:V4 days long, but it's a tiny bit shorter than that. To make up for that tiny falling-sbort, three leap years have to be omitted every four centuries, and by the Gregorian calendar those omissions come in any year ending in 00 that is not divisible by 400, even though such a year would be leap in the Julian calendar. "That means," and he pounded his fist on the table again, "that .1900 was not a leap year. There was no leap year between 1896 and .1904. There were seven consecutive years Of 365 days each, instead of three."

Henry said, "Doesn't that upset the perpetual calendar that you described?" "Yes, it does. The perpetual calendar for the 1800s meets the one for the 1900s in the middle, so to speak." "In that case, what was the last year before 1970 in which a Friday the thirteenth in February fell in a leap year?" "I'll have to figure it out," said Halsted, his pen racing over a new napkin. "Ah, ah," he muttered, then threw his pen down on the table and said, "In 1880, by God." "Forty years before 1970," said Henry, "so that on the day that Hennessy wrote his note, an unlucky day in February was not fol-

lowed by an unlucky day in March for the first time in forty years, and it was quite fair for him to call it, flamboyantly, a forty-year miracle. It seems to me that February 13, 1920, is the only possible day in his entire lifetime on which that note could have been written." "And so it does to me," said Halsted. "And to me," said Fletcher. "I thank you, gentlemen. And especially you, Henry. If I can argue this out correctly now-" "I'm sure," said Henry, "that Mr. Halsted will be glad to help out."

i o Afterword

I had to write this one. On Friday, December 13, 1974, 1 was co-host for that month's meeting of the Trap Door Spiders. (The Trap Door Spiders have two hosts and twice the membership of the Black Widowers, you see.) I had picked a new restaurant and was particularly anxious that everything go well.

I had guaranteed that twelve to fifteen members would show up and I feared that we might not make the number and that I would have a bad time with the restaurant. I counted them as they came in and when number twelve arrived I was relieved. (And the restaurant was pleased too. We were served an excellent meal with superb service-though, of course, no Henry.)

Then, just as the cocktail hour was over and we sat down to dinner, in came member number thirteen. Personally, I think it's a credit to the membership that not one person present seemed the least bit concerned that we were thirteen at the table on Friday the thirteenth (and as far as I know, nothing has happened as a result.)

I must admit I was concerned, because I could not let such an event pass without beginning to work on a Black Widower plot at once. Again Ellery Queen's Mystery Magazine felt this to be too complicated a situation, and I passed it on to F 6 SF, which took it It appeared in the January 1976 issue.