“Just what I was going to point out,” broke in Marsland.
“Quite so. But it was possible that 396 meant Psalm 39, 6. Therefore I turned to the thirty-ninth Psalm. Verse six of that Psalm reads:
“‘Surely every man walketh in a vain shew: surely they are disquieted in vain: he heapeth up riches, and knoweth not who shall gather.’”
“Appropriate enough,” commented Marsland.
“There remained the final 6, under the 396, to be explained, before I was able to start on the table which had been used to build up the cryptogram. The fact that the figures in the outside circle start at 6 indicated that there was some connection between it and the inner 6. I came to the conclusion that the inner 6 meant one of two things: either the designer preferred to start from the number 6 because he thought the figure 1 was too clear an indication of the commencement of his cryptogram, or else he made his start from the sixth letter of the text. I thought the former the likelier solution, but I tried them both, to make sure. The first five figures on the latter solution gave me a recurring Y, which indicated that I was on the wrong track because it was essential there should be no recurring letters. There were no recurring letters in the other key.
“Now, assuming that my interpretation of the solitary six in the circle was correct—that the old man started from six because he thought the use of the figure one gave away too much—we will substitute for these figures the letters which appear underneath them in the table. The substitution gives us the following row of letters:
S R E L Y V M N W A K T H I U D Q P C O S
“This is the line of letters from which we will endeavour to reconstruct the old man’s cryptogram. We can, I think, go forward with the assurance that they are the actual letters represented by the cryptogram, for several reasons. There are no recurring letters, and they represent every letter in the text in consecutive order, with three exceptions which are capable of a simple explanation. The U has been taken from the second ‘surely’ instead of the first, to mislead the solver. Otherwise you would have surely for the first five numbers, which would be too clear an indication. The same reason exists for making A the tenth letter instead of the eighth; which would reveal the word ‘man.’ The final letter—the ‘G’ in ‘gather’—has been excluded, for a reason which I will presently explain.”
“What about the second S—the final letter? Do you not call that a recurring letter?” asked Marsland, who was closely examining the table the detective had prepared.
“Not in the cryptographic sense. It is the first letter of the text repeated after the line had been completed without recurring letters. There is a special reason for its use. The old man has worked on what is called the keyword cipher, which is the most difficult of all ciphers to discover. This system consists of various arrangements, more or less elaborate, of tables of letters, set down in the form of the multiplication table, and from the table agreed upon messages are constructed whose solution depends on the use of some preconcerted keyword. The most scientific adaptation of this principle was constructed by Admiral Sir Francis Beaufort. In his system the letters of the alphabet are set down one under another from A to Z, then A is added to the line. The next line starts with B and runs to another B at the bottom. You continue till you have the whole alphabet set down in this fashion. From this table and an agreed keyword, which may consist of a proper name or a sentence of several words, you construct a cipher message.”
“How?” asked Marsland, in a tone of keen interest.
“That is what I now propose to demonstrate to you, if, as I think, the old man constructed his cryptogram in accordance with this principle. I have come to the conclusion that he modified and adapted this system to his own ends, using the letters of the text from the Bible to conceal it better, and then made it more difficult still by turning the letters into figures after the manner I have described. He has also made a slight but not uncommon variation from the Beaufort principle by striking out the ‘G’ in ‘gather,’ which would follow the ‘O’ if every letter in the text was used once, and substituting the final S, instead of placing the ‘S’ after ‘G.’ But the clue that suggested to my mind that he had worked on this principle are the two figures 6 coming together at the top of the circle. In the substituted letters they form two S’s. Now, why does he have two S’s when he carefully avoids recurring letters in the rest of the table? And why did he insert the first S again, as represented by the figure 6, instead of taking the next S in this table?
“In pondering over these points I discovered, as I believe, the system of cryptogram he used to construct his secret. He wanted to make the cryptogram difficult of solution, but at the same time he wanted to give some indication of the form of cryptogram he was using when his heirs came to search for the money. The recurring S indicates that he was working on a modification of the system I have explained, in which you add the first letter of your first column to the bottom, and continue on that system throughout the table. It is not much of a hint, because we have got to find the keyword before we can use the table, but by its help we will start with the assumption that the old man worked on the following table:
S R E L Y V M N W A K T H I U D Q P C O S
R E L Y V M N W A K T H I U D Q P C O S R
E L Y V M N W A K T H I U D Q P C O S R E
L Y V M N W A K T H I U D Q P C O S R E L
Y V M N W A K T H I U D Q P C O S R E L Y
V M N W A K T H I U D Q P C O S R E L Y V
M N W A K T H I U D Q P C O S R E L Y V M
N W A K T H I U D Q P C O S R E L Y V M N
W A K T H I U D Q P C O S R E L Y V M N W
A K T H I U D Q P C O S R E L Y V M N W A
K T H I U D Q P C O S R E L Y V M N W A K
T H I U D Q P C O S R E L Y V M N W A K T
H I U D Q P C O S R E L Y V M N W A K T H
I U D Q P C O S R E L Y V M N W A K T H I
U D Q P C O S R E L Y V M N W A K T H I U
D Q P C O S R E L Y V M N W A K T H I U D
Q P C O S R E L Y V M N W A K T H I U D Q
P C O S R E L Y V M N W A K T H I U D Q P
C O S R E L Y V M N W A K T H I U D Q P C
O S R E L Y V M N W A K T H I U D Q P C O
S R E L Y V M N W A K T H I U D Q P C O S
“It is from this table, unless I am very much mistaken, that he constructed the cipher at the top of the sheet,” said Crewe.
Marsland examined the curious table of letters, with close scrutiny, from various points of view, finally reversing it and examining it upside-down. He returned it to Crewe with a disappointed shake of his head.
“I can make nothing of it,” he said.
“It is necessary for us to discover the keyword he worked on before we can make use of it,” said Crewe. “Once we get the keyword, we will have no trouble in deciphering the mysterious message. The keyword is the real difficulty in ciphers of this kind. It is like the keyword of a combination lock. Without it, you cannot unlock the cipher. It is absolutely insoluble. Suppose, for example, he had picked a word at random out of the dictionary, and died without divulging it to anybody, we should have to go through the dictionary word for word, working the table on each word, till we came to the right one.”
“But that would take years,” exclaimed Marsland blankly.
“Unless we hit on it by a lucky accident. That is why the keyword cipher is practically insoluble without knowledge of the keyword. It is not even necessary to have a word. A prearranged code of letters will do, known only to the composer of the cryptogram. If he wanted anybody else to decipher his cryptogram, he would have to divulge to him not only the form of table he worked on but the code of letters forming the keyword.”
“Well, I do not see we are much further forward,” said Marsland despondently. “Of course, it’s very clever of you to have found out what you have, but we are helpless without the keyword. The old man is not likely to have divulged it to anybody.”
“You are wron
g,” said Crewe. “He has divulged it.”
“To whom?”
“To this paper. As I said before, he did not want his cryptogram to be insoluble; he wanted his heirs to have his money, but he did not want it found very easily. You have forgotten the texts at the bottom of the paper. They have not been placed there for nothing. The keyword is hidden in them.”
“I forgot all about the texts—I was so interested in your reconstruction of the cryptogram,” said Marsland. “As you say, he didn’t put the texts there for nothing, so it seems likely that he has hidden the keyword in them. But even now we may have some difficulty in finding it. Do you propose to take the texts word for word, testing each with the table, till you find the right one?”
“That would take a long while,” said Crewe. “I hope to simplify the process considerably. In fact, I think I have already discovered the keyword.”
“You have!” exclaimed Marsland, in astonishment. “How have you managed that?”
“By deduction from the facts in front of us—or perhaps I should say by reflecting on the hints placed in the texts. Isn’t there something about those texts that strikes you as peculiar?”
Marsland examined them attentively for some time, and shook his head.
“I’m afraid I’m not sufficiently well up in the Scriptures to notice anything peculiar about them. I should say they were from the Old Testament, but I couldn’t tell you what part of it.”
“The texts are from the Old Testament, from Jeremiah XXV and Isaiah VII. They are remarkable for the fact that they represent two passages—the only two instances in the whole Bible—where the writers used cryptograms to hide their actual meaning. In the first instance the prophet, Jeremiah, living in dangerous times, veils his attack on the King of Babylon by writing Sheshak for Babel—Babylon; that is, instead of using B B L, the second and twelfth letters of the Hebrew alphabet, from the beginning, he wrote Sh Sh K from the end—a simple form of cryptogram which is frequently used, even now. In the second instance the prophet Isaiah, working on a very similar form of cryptogram, writes ‘Tabeal’ for ‘Remaliah.’
“Now, we are faced by two facts concerning the presence of these two texts on the paper containing the cryptogram. In the first place, the cryptogram was complete without the texts; for what purpose, then, could they have been at the bottom of the sheet except to give a clue to the discovery of that keyword without which no recovery of the hidden treasure was possible, unless it was found by a lucky chance? In the second place, the selection by the old man of the only two cryptographic texts in the Bible was certainly not chance, but part of a deliberate harmonious design to guide the intelligent searcher to the right keyword. He was evidently versed in cryptography, constructed this one as carefully as a mechanic putting together a piece of mechanism, fitting all the parts carefully into one another. The figures in the centre of the circle give the key to the outside figures: the outside figures are the key to the cryptographic table of letters from which the cryptogram is to be solved; there remains the key to be found. It is not likely that the composer of such an ingenious cryptogram would leave the keyword to guesswork.
“The whole thing is a Bible cryptogram from first to last: figures, letters, words, and texts. It is even drawn on a sheet cut from the Bible. Why? Such an act might be deemed irreverent in a deeply religious man like the old man was, but when we piece the thing together we find that he was actuated by a religious spirit throughout. Not the least skilful part of his cryptogram is his concealment of the keyword in the text at the bottom. The text would convey nothing to most people, for very few people know anything about cryptograms, still fewer people would know that these texts contain the only two cryptograms in the Bible. Therefore, in accordance with his harmonious design, it seems to me that the keyword should be found in the five alternatives of the cryptic texts: Babel, Babylon, Sheshak, Remaliah, or Tabeal.
“Babel and Babylon may be discarded because there is no letter B in the cryptographic table, and it is essential that the keyword shall contain no letter which doesn’t also appear in the table. ‘Sheshak’ may also be discarded for the present as unlikely because of the awkwardness of the recurring ‘Sh’ in a keyword. There remain Tabeal and Remaliah. The tendency of the composer would be to use the longer word, because a long keyword is the better for the purpose. I think, therefore, we should first try whether Remaliah is the keyword we are in search of.”
“By Jove, Crewe, that is cleverly reasoned out!” exclaimed Marsland, in some excitement. “Let’s put it to the test. How do we apply this keyword to the table?”
“Easily enough. On this sheet of paper we will write down the cryptogram; and the keyword underneath it, letter for letter.
“Now, the first word of the cryptogram is T. Look in the first column of the table for it, and then run your eye across the table for the first letter of the keyword. When you have found it, look at the top of the column and tell me the letter.”
“K,” said Marsland.
“Very well, then. We put down ‘K’ as the first word of the solution and proceed in like manner through the whole of the cipher. The second letter is Y—find it in the table, then look across for the second letter of the key E, and then to the top of the column. What letter have you?”
“C,” said Marsland.
“KC, then, are the first two letters of our solution, and we go on to the third, always repeating the same process. N in the first column, M across, and the top gives you?”
“O,” said Marsland.
“The next letter is M in the cryptogram and A in the keyword. What does the top of the column give you?”
“L,” replied Marsland. “But I say, Crewe, do you think we are on the right track? K, C, O, L, is a queer start for a word isn’t it? I know of no word commencing like that.”
“I may be mistaken, but I do not think so,” replied Crewe firmly. “Let us keep on till we’ve finished it, at all events.”
They resumed their task, and ultimately brought out the letters: K, C, O, L, C, H, C, R, A, E, S. Marsland gazed at the result in dismay.
“By Jove, we’re on the wrong track,” he said ruefully. “It is the wrong word, Crewe. These letters mean nothing; you’ll have to try again.”
But Crewe did not reply. He was examining the result of his night’s labours closely. Suddenly he put down the paper with an unusual light in his eye.
“No,” he said. “I am right, the old man was thorough to the last detail. He has given another clue to his heirs in the circle and the two lines. They represent a clock face. But the figures round them run the reverse way to clock figures. The cryptogram reads backwards. Hold it up to that mirror, and see.”
Marsland did so, and laid down the paper with a look of bewilderment.
“Search clock! The old grandfather clock at Cliff Farm!” he said.
CHAPTER XXIV
As the car swept around the deserted sea-front and through the scattered outskirts of the town, Crewe gradually increased the going, till by the time Staveley was left behind, and the Cliff road stretched in front of them, his powerful car was driving along at top speed. The night was not dark for the time of year; the windings of the road were visible some distance ahead: from the cliffs the rollers of the incoming tide could be seen breaking into white froth on the rocks below.
“It has occurred to me that, for a man who was afraid of a German invasion, old Lumsden selected a very bad hiding-place for his money,” said Marsland. “He could not have known of the reputation the German soldiers made for themselves in stealing French clocks in the war of 1870.”
“Perhaps not,” replied Crewe. “But I do not think he intended to leave the money in the clock when the Germans came. If he fled from the farm he would have taken it with him. His object in hiding it in the clock was to have it constantly under his eye.”
The car mounted the hill to the cutting through the cliff road near their destination, and as the road dipped downwards Crewe slackened the pace
. Both of them were looking across towards the farm on the left. As it came into view Crewe exclaimed to his companion:
“Did you see that?”
“A light!” said Marsland excitedly.
“It is gone now; it was probably a match. There must be some one there. I wonder who it could be?”
“Perhaps it is Gillett. We will soon see.”
“No, we will drive past. It may be some one who wants to escape being seen. We will run the car off the road a little way down past the farm, then extinguish the lights and make our way back.”
He increased the pace of the car so that if there was any one at the farm it would appear that the car was going on to Ashlingsea. They both kept their eyes on the house as the car sped past, but there was no repetition of the flash of light they had seen. Less than half a mile away Crewe shut off the engine, and carefully ran the car off the road on to a grassy path. He extinguished the lights and jumped out of the car. He took an electric torch from his overcoat pocket and after turning it on to see if it was in order he set off in the direction of the farm.
The Third Mystery Page 76