‘You must not intervene,’ Holmes insisted in the same calm voice.
‘Information must continue to flow. The Morse code signals must be allowed to go out as usual. The best you can do for the moment is to let them carry falsified legends of ships’ particulars or misleading figures of turbine and boiler performance.’
Fisher pulled a face.
‘It will be difficult. We may cause confusion in our own ranks.’
‘Nevertheless, it must be done,’ said Holmes patiently. ‘There is no other way.’
A dozen times in the next few weeks a plain envelope arrived ‘by hand of messenger,’ usually a young Royal Navy staff officer in mufti bearing details of the intercepted signals. Once again Sherlock Holmes worked day and night. This time not a sentence, not a phrase, in
Through the Looking Glass and what Alice found there
matched the garbled blocks of fourteen letters. Perhaps, as a matter of routine, our enemies had switched to another text as their key. Holmes grew more gloomy as the October days drew in and November took its turn.
‘They cannot suspect anything amiss,’ I said, trying to reassure him. ‘After all, their signals are still being sent out.’
He did not seem to be much reassured beyond sighing and saying, ‘It means we are left with trial and error, Watson. Brother Mycroft and the advanced mathematicians are apt to refer to certain numbers so vast that they are “beyond computation.” Such are the odds against us now.’
He sat one afternoon with a dozen transcripts before him. Jackie Fisher was at him every day, insisting that until one more signal was deciphered there was no way of knowing whether our spy had been deceived by the falsified documents.
Presently, Mrs. Hudson brought a tray of tea things and set the silver teapot down beside him on the table. As the good lady went out again, Holmes turned to me and said, ‘This is all wrong. It cannot be done.’ I was shaken by his remark, for it was the only occasion on which I had heard him use such words. Then he paused and corrected himself.
‘It cannot be done in the way that we are doing it now. The key may be in any book in the world or in a single word used over and over. We are being led by a ring in our noses. Our mistake, Watson, is that we are beginning at the beginning, when we should be beginning at the end.’
‘How can we begin at the end? We need the key first to decipher the message.’
He shook his head.
‘We shall never fathom the key. That is what they count upon. At a guess, it would take a length of time approximately equal to the present age of the universe. Let us ignore the key and, instead, try to guess correctly even a small part of the signal sent. We shall try to work backwards from the letters of the encrypted signal to the letters of the code. Once we have part of the code, we may work forward to the rest.’
Having no better suggestion, I let him have his way.
‘However elusive the key to the code, my dear Watson, we may be sure of certain words in the messages sent. Remove their disguise and you have part of the key.’
‘Such as?’
‘Given the events of the recent past, it is inconceivable that ‘
Dreadnought
’ should not be among the words in the signals. May I be shot if one block of fourteen letters does not contain that name. The secrets of that class of ship is the prize they seek.’
‘Dreadnought is eleven letters, not fourteen,’ I said cautiously.
‘Very well. Let us allow for Teutonic formality. ‘
HMS DREADNOUGHT
’ will give us fourteen letters.’
He gathered up the transcripts and we prepared to work through the night. It was a little after two in the morning when we were working on a recent signal. The fourteen grouped letters were still gibberish—
KQSUDIMUUCFSLL
.
‘Once again,’ said Holmes patiently, ‘suppose that these letters signal ‘HMS
Dreadnought
,’ what will the cipher key be?’
Carefully, he began to trace the sequence back. We had tested hundreds of these groups against the reading ‘
HMS DREADNOUGHT
’ in the hope each time that this was their message—but without success. One by one he followed the present string of letters to see whether they might yield a key. Two minutes later we stared at the result. It was a key and a message in one.
‘DEAR ME, MR HOLMES’
I felt the shock like a blow to the chest. The thing was impossible, and yet, as we had worked through the night, it now seemed as if our distant and invisible enemies had been thinking our very thoughts for us. We got up and went in silence to our usual arm chairs. After so much work, my despair was all the greater.
‘Well, that is the end of it,’ I said miserably. ‘How the devil could they know?’
Holmes knocked his pipe out against the fireplace and refilled it. For a moment he said nothing. Then he lit his pipe and turned to me.
‘I believe they could not know. Therefore, they did not know. If I am right, this is in every sense a lucky shot, a shot in a thousand. It has a ring of heavy Germanic facetiousness. You will recall that several of my adventures, such as they are, lie in the hands of the public, thanks to your gift for romanticized narratives. I should find it remarkable if they were not read by such men as these. This was a phrase of the late Professor Moriarty’s and has circulated widely. We must proceed on the assumption that it is pleasantry among our adversaries and no more.’
‘Can we do that?’
He seemed remarkably unruffled.
‘You will observe that several signals were sent after the date of this one. That surely would not have happened had they thought the hunters were on their trail. You will also recall that when our visitors have come here, I have surveyed the street from time to time. I do not think that they were followed or watched. All the same, it may come to that. I think it is as well that we should hold future discussions with Sir John and Lord Esher away from public scrutiny.’
I was far from reassured. On the following afternoon a private room of the Diogenes Club was secured for us by Mycroft Holmes. We had thrown off any pursuers by taking a twopenny bus from Baker Street to Oxford Circus, alighting, then getting on again after the waiting passengers had done so. Anyone following us would have had to get off and on as well. None did.
Furthermore, Sir John Fisher assured us that the Morse code transmissions had continued. Two signals were intercepted in the previous week. Had the signallers believed that their codes had been deciphered and that they themselves were in danger, they would have fled before then. It seemed as if the use of ‘Sherlock Holmes’ in their key was, after all, merely a joke among those who thought themselves superior even to the famous detective.
Yet my relief was short-lived, as Sir John spread before us the latest transcripts. I expected the usual groups of fourteen letters. What I saw was quite different.
72- 48 - 03- 61-74 | 82-30 - 42-13- 06 -53 | 29-71- 46 -22 | 38 -72- 49-17 |
The First Sea Lord looked up at us.
‘They have abandoned Morse for a two-digit code. Our monitors now hear two series of short pulses from one to ten. A pause. Two more. Then a long pulse, no doubt to signal the end of a word. It is something entirely new. At any rate, our people have never come across the like of it. What do you say to it now?’
Holmes stretched out his long legs and touched his fingertips together.
‘Never fear, Sir John. I believe you are wrong in supposing this device to be new. Something tells me that it goes back many centuries. Moreover, the fact that the signals are still going out confirms, as you say, that their reference to me was mere whimsy inspired by Watson’s turn for romantic fiction. In that, as so often in such matters, it seems I have been proved correct.’
Further precautions were taken. There was no more post ‘by hand of officer.’ Intercepted signals were to be relayed direct to us from the rooftop mast of Admiralty Arch. Pride of place on his worktable went to an ‘ink-writer’ devised by Holmes some years earlier. From a wire aerial it could take down messages in Morse. Rescued from the attic, this contraption worked on an accumulator battery. I saw only a square glass jar filled with sulphuric acid and distilled water. By means I did not comprehend, an endless strip of white paper moved slowly above the inkwell as a message was received.
A stylus attached to the mechanism kept pace with the signals of each transmission, drawing dashes or dots in time with it. Holmes assured me that it required only an electric current from the battery to pass through a magnet. A lever would then lift a small ink wheel into contact with the paper.
‘The length of an ink mark depends upon how long the current flows,’ he said, not for the first time. ‘Dots or dashes are determined by the duration of the current. By this means, our friends at Admiralty Arch can transmit to us in Morse code. In the case of the new code, however, they will transmit dashes for digits of ten and dots for single numerals, making up the pairs of numbers that our adversaries now appear to prefer.’
‘Black magic!’ I said uneasily.
He laughed and shook his head.
‘Not in the least, my dear Watson. Have you noticed, by the way, that each pair of numbers in the ciphers appears to stand for something like a letter or a syllable? Taken together, they must certainly equate to an alphabet in some form. In every one of the ciphers the double digits run from one—with a nought before it—to eighty-seven. Now consider this. That is far too few for a system like the Chinese, where each ideogram stands for a word and many thousands of symbols are required. At the same time, it is rather too many for a purely alphabetical system as we know it. Our alphabet has only twenty-six letters, after all, and the Greek has only twenty-four.’
‘Very well, then eighty-seven symbols cannot be an alphabet.’
He chuckled.
‘Not as you or I think of it, Watson. However, I would bet a good deal that what we are looking at is a code written in syllables rather than letters, though based upon an alphabet. That should narrow down our hunt considerably.’
‘I wish I could see how. As yet we do not even know which alphabet it may be. This is worse than your looking-glass nonsense.’
Before he could reply, there was a knock at the door and Mrs. Hudson came in.
‘Mr. Lestrade and a lady to see Mr. Holmes, supposing it might be convenient.’
I would have suggested it was anything but convenient. Holmes beamed at her.
‘By all means, Mrs. Hudson. It will be a sad day when we are too busy to see Inspector Lestrade.’
Our landlady withdrew, and after several measured steps upon the staircase her place in the doorway was taken by Lestrade, our small but wiry bulldog as I thought of him. The lady in his company seemed not the least remarkable. She looked very much what she proved to be, a widow of sixty obliged to take in lodgers, dressed on this occasion in a dark red hat, a brown travelling-cloak and a fox fur of uncertain quality about her neck.
‘Good morning, gentlemen,’ said our Scotland Yard friend. ‘Allow me to introduce you to Mrs. Annie Constantine of Nile Street, Sheerness.’
Holmes bowed as if before a duchess.
‘My dear lady, my dear Lestrade, you are both most welcome. Please take the chairs by the mantelpiece and tell us to what we owe the honour of this visit. I confess I have been expecting something of the sort for two or three hours.’
Lestrade did not look best pleased by this. When Mrs. Constantine had been arranged in a chair by the fireside and fresh tea had been ordered, he sat down opposite Holmes and said: ‘Expecting what exactly, Mr. Holmes?’ His eyes widened and he looked more than a trifle put out. ‘I do not see how you can have been expecting something you knew nothing about.’
Holmes laughed merrily but there was no merriment behind his eyes.
‘Allow me to explain. Several days ago it was arranged that Superintendent Melville of the Criminal Investigation Department at Scotland Yard should be informed by his inspectors of any unusual entry by beat constables of the London area in their station Occurrence Book. Not crimes, you understand, but anything out of the ordinary that was reported—the results were to be conveyed to me. Special attention was to be given to the Thames estuary.’
‘Ah, then you were not being so very clever just now, were you, Mr. Holmes?’
My friend ignored this snub.
‘I said to myself at the time, if there is anything worthy of note, it will be an officer with the capacity and shrewdness of Inspector Lestrade who recognizes it and acts at once.’
There was a pause while the morning tea tray was set down and then Holmes began to pour.
‘Perhaps I had better hear what this good lady has to tell us,’ he said genially, handing her a cup.
Mrs. Constantine looked at Lestrade, as if for permission to speak, then turned to Holmes.
‘As you mayn’t have heard, Mr. Holmes, I keep a lodger. Usually a young single gentleman that has the first floor back. I breakfast him, but otherwise he does for himself. Last year Mr. Henshaw came to me, Mr. Charles Henshaw, a very genteel young man. He teaches French, not at school but to professional young men with examinations to pass. They come to the house and he has the use of the downstairs drawing room to give them lessons. Otherwise, the upstairs is his domain.’
‘Really?’ said Holmes indifferently, though for reasons I could not see he was missing neither a word nor an inflection of her voice.
‘A nice young man?’
‘Ever so nice. Regular at the Congregational chapel on Sundays. And I don’t mind telling you that if I’d known there was to be so much trouble as this, I’d have acted otherwise on Monday morning.’
‘What trouble precisely, madam?’
‘Well, Mr. Holmes, it was the middle of this last Monday morning and everything in the street was as quiet as you could wish. Nothing but Mr. Lethbridge the constable, that lives two roads away, coming down on his beat. Then it happened.’
She sat back and folded her arms, as if the matter was at an end.
‘What happened, Mrs. Constantine?’