From the comfortable seats of our vehicle, I turned for one last sight of the bewitching palace. A bemused Sir Penderel was staring at the Prince. Ferdinand bent over again, shaking with compulsive laughter, waving the sword stick above his back. We turned a corner. The Prince and his Palace were lost to sight.
When the noise of the wind and the vehicle’s motor made it impossible for our driver to hear my words I turned to my companion.
‘Holmes, I am unable to contain my curiosity for a moment longer. What was that telegram all about?’
‘It was merely a message from the Library of the British Museum.’
‘A message from the Library of the British Museum?’ I parroted in wonderment. ‘And on what subject were you in touch with the British Museum?’
‘The preservation of ancient parchments.’
His brevity exasperated me. ‘Holmes, I insist on the detail! What did the Library say about the preservation of ancient parchments? Why should such information first seem to put the fear of God into the Prince and then make him nearly collapse with laughter?’
‘It concerns the Codex.’
‘Ah, the Codex, of course!’ I responded with a chortle. ‘I shall never forget the look on his face when he found it had been returned. The very name Sherlock Holmes must have - ’
‘It may not have been as great a surprise to Ferdinand as you imagine,’ my comrade interrupted.
I swivelled to look directly at him.
‘By which you mean - ?’
‘To judge from your expression, Watson, the Prince must truly be as consummate an actor as the Roman emperor Nero. You recall my axiom that misdeeds bear a family resemblance? That if you have the details of a thousand at your finger’s end, it is odd if you are unable to unravel the thousand and first? What of the distant echo of The Adventure of the Second Stain? Tell me, according to the Prince, how long had the Codex been stored in that cave?’
‘Almost from the day he took the throne.’
‘So he informed us. How long has that been?’
‘Twelve years.’
‘Thirteen to be exact, since 1887,’ Holmes replied. ‘He has a superstitious aversion to the number thirteen, hence he used twelve. Nevertheless, even one year would have been out of the question, let alone a baker’s dozen.’
‘I don’t follow you, Holmes.’
‘He gave us four reasons for hiding the Codex in the cliff-caves, one supernatural, and three scientific. Do you recall the latter?’
‘I have them written down,’ I replied.
‘There is some way to go before we reach the River Danube, perhaps you would be kind enough - ?’ He pointed to my Gladstone bag.
I pulled it to me and retrieved my note-book.
‘So, Watson, my dear friend, the first - ?’
‘The air in the cave interior is absolutely clean and free of dust.’
‘Good! And the second?’
‘The cave interior shields the Codex from bright light.’
‘Sunlight especially. Third?’
‘The ambient temperature is quite low. It hardly varies a degree throughout the year.’
‘Being?’
‘A permanent 11 to 12 degrees Centigrade.’
‘In our language that would be?’
‘A little over 50 degrees Fahrenheit.’
‘All in all, the caves would appear to be the perfect place to store so venerable a manuscript, don’t you agree?’
‘They would, Holmes,’ I replied. ‘So why - ?’
‘My dear fellow, there was one absolutely vital matter which our wily friend chose not to mention.’
‘That being?’
Holmes withdrew the telegram from a pocket and handed it to me.
‘Read it aloud,’ he commanded. ‘I congratulate you, Watson. It was you who gave me the clue.’
Deeply engaged by Holmes’s complimentary remark, I began, ‘‘Preservation of ancient manuscripts. Fumigate and store in a dust-free environment. Low light and temperature levels are critical. Exposure to sunlight should be kept to the absolute minimum. As a rule of thumb, the lower and more consistent the temperature the better’.’
My eyebrows gathered in a frown. ‘Well, Holmes, so far it seems - ’
‘Please read on, dear chap.’
I went on, ‘‘However, in the experience of the British Library the most critical requirement for conservation is low relative humidity, between a minimum of 30% and a maximum of 50%. This prevents the growth of fungi (mould and mildew). Relative humidities at the lower end of this range are preferable since deterioration takes place at a slower rate’.’
I looked up at my companion with a puzzled expression. ‘Holmes, you said I gave you the clue - what clue?’
‘Humidity,’ Holmes repeated. ‘The fourth ingredient. The most vital of them all. When we set off from Sofia the Prince told us the monks used to produce a special wine in the galleries of the caves. According to him, it closely resembled the wine produced in Champagne - do you recall his peroration on the wines of Bulgaria?’
‘I do, yes,’ I replied, ‘but - ’
‘Anyone with the Prince’s knowledge of alchemy is aware that high humidity is an essential part of producing such wines. Humidity over 75% for red wine and over 85% for the white is ideal for wine-ageing and barrel storage. You must recall the extreme humidity of the Baptistery?’
‘It was very humid, certainly.’
‘About 80%, I would estimate. Would you agree?’
‘It was quite like the approach of the South Asia monsoon season, yes.’
‘I have remarked on this before, Watson, that you have been of the most vital use to me in several of our cases, and again in this. I spotted how you sweated like a pig despite the modest temperature. It certainly suggests your Polka and Mazurka days are over, my dear fellow. No more quick-stepping to a Fife and Drum band, you must embrace the Waltz and the Two-Step. Even before we reached the Altar stone it seemed odd to me that a manuscript of such antiquity and mystical power would be left in such conditions. I realised at once it was never taken from its hiding-place BECAUSE IT WAS NEVER STORED THERE. At most the Codex had been placed in the caves a matter of days, even hours, before our arrival.’
‘But the Prince said he had sought the advice of the British Museum, the very source you - ’
‘Certainly he said that, though I suggest it was extremely unlikely, or at the very least we can say he didn’t follow it,’ Holmes replied laughing.
‘Then why - ?’
‘Our friend needed to remove himself from the Capital while the murder of Captain Barrington took place. By dreaming up the theft of the Codex the Prince had a fine excuse to invite us to his country. By pretending the Codex had been stored in those far-off caves, he had reason to take us on a trip lasting at least three days.’
‘He must have overlooked what a fine chemist you are, until you handed him the telegram. That’s when he realised you had seen through the deception all along.’
‘He realised it at once.’
‘Which explains why he - ’
‘Scowled? Yes. His first thought must have been I was about to expose his trickery to the world. Within seconds it dawned upon him we must have been silenced. Why otherwise would I hand him the evidence which could indicate the disappearance of the Codex was part of a murderous plot? Why not simply put such information in the hands of Messrs. Reuter or the Balkan correspondent of the Pall Mall Gazette and let public uproar take its course? The Prince realised our own Government had hamstrung us. That was when he burst into laughter.’