“If our estimate of the room temperature is correct, Watson-and I do not think we can be far out-the specific gravity of this mineral is registered as 3.993. I do not believe it can be andradite, for I have tried it judiciously with a penknife and that will not produce a scratch upon it. Nor, I think can it be zircon of whatever type. I therefore deduce that what we are presented with appears to be a species of corundum. Only caborundum and the diamond are harder than this. Indeed, in the scale of hardness drawn up by the admirable Professor Friedrich Mohs in 1812, only the diamond exceeds it. This cannot possibly be a diamond for its specific gravity is far too high. That I believe is as far as we can go for the present.”
Holmes had given me the opportunity I had been looking for. I had not wished to annoy him or to suggest that a piece of grit picked up from the Lincolnshire fens was unlikely to be of any value or relevance to the case whatever. However, I had been thinking wistfully of sleep. A long journey lay ahead in the morning. I yawned, stretched, made my excuses and withdrew to bed.
I suppose it was about half-past eleven when my head touched the pillow. I was woken after several hours by a dreadful screaming. It might have been a banshee-or at least the sound which I had always assumed a banshee would make. I sat up with heart pounding and, at the same time, a sense of considerable irritation.
By the time I had lit a candle, the high-pitched sound came again. It was a demented shrieking from somewhere below me. Now that I was fully awake, I recognised that whatever its origins, they were mechanical and not animal. The time by my watch was ten minutes past three in the morning. It was plain that Sherlock Holmes had not yet gone to bed.
I had not the least doubt that this disturbance would be heard on every floor of the house, and more importantly throughout those of the houses on either side. Pulling on my dressing-gown, I tied its belt and made my way by candlelight to the stairs. I began to descend to our sitting-room. Half-way down, I was aware of a lone figure on the little chair outside the door of that room. The flickering candle showed me Mrs Hudson. She was wrapped in a shawl round her nightdress, rocking to and fro a little. With her face buried in her hands she uttered a repeated protest that was almost a dry sob.
“Oh, that noise! Oh, that dreadful, dreadful noise! Why will he not stop?”
She looked up and saw me with a candlestick in my hand, standing at the top of the staircase like Banquo’s ghost on the stage of the Lyceum Theatre.
“Oh, Dr Watson! None of my gentlemen, in all these years, has ever been such a trial as Mr Holmes! What am I to do? What am I to say tomorrow morning to Mrs Armitage next door?”
“This is too bad,” I said soothingly, “Go back to bed, Mrs Hudson, and leave this to me. I promise you that the noise will stop.”
I was becoming more impatient with every moment of delay. I tried the handle of the sitting-room door and found it locked. I hammered on the oak panel with all the majesty of the law. There was a pause in the din. I sensed Holmes coming towards me and a key rattled in the lock. He flung open the door and almost pulled me into the room, his eyes gleaming. I now saw that he had screwed his carborundum wheel to the edge of the work-table and that it was the friction of its hard grey stone cleaning a penknife blade that had caused the din. The wheel had apparently also been at work upon Miss Chastelnau’s pebble. On one side of the dun-coated stone was now revealed what looked like a dull speck of royal blue glass.
“Corundum, Watson! The stuff of rubies and sapphires. A blue sapphire fit for the crown of England! Lost in the muddy dullness of time and neglect! After I heard the good lady’s story, I suspected that something like this must be the truth, though I hardly dared to believe it. Once we had been given a specific gravity of 3.993, I was certain. The figure is sometimes a fraction higher but the room temperature would account for that.”
“Corundum?”
“Corundum yields the ruby or the sapphire, according to the form of its crystals. In white light, the ruby absorbs every shade but red and therefore it glows red. Sapphire reflects only blue, as in this case. Take the jeweller’s glass and look. You will observe that the crystals are quite clearly tall and pointed, as in the sapphire, and not shorter and rectangular as in the ruby.”
“It looks very little like a jewel to me.”
“Nor should it after so many centuries in the earth. That is something which skilled polishing will amend in due course.”
“But not tonight, unless you want Mrs Hudson to throw both of us out into the street.”
He chuckled, as if in a fit of mischief.
“Not tonight, then. We know enough now to put us on the track. Tomorrow will be soon enough to prove that we are right.”
“Meantime we are to assume that the Chastelnau brothers have been made away with for such a miserable little object as this?”
“Oh no, my dear fellow. I believe you have entirely failed to understand the nature of the problem. More is at stake than this. Far, far more.”
3
The next morning saw us on the train to Cambridge, Ely, King’s Lynn and finally across the new river bridge to Sutton Cross. The fog dispersed on the northern outskirts of London. A fine October day with a pale blue sky faded to a yellow edging at the horizon. One sees almost nothing of the Cambridge colleges from the railway and very little of the fine medieval cathedral towers of Ely. But Holmes was not concerned with the view. He had wired Inspector Lestrade at Scotland Yard, mentioning our interest in the case of the missing brothers and requesting him to smooth our path with the Lincolnshire constabulary as far as was possible. Lestrade’s reply suggested that if we wished to waste our time over a commonplace case of “missing from home” or “found drowned,” we were welcome to do so.
Holmes read a good deal on train journeys but always with a set purpose. I could never imagine him feeling that he should cultivate the charm of Jane Austen or the melodrama of Sir Walter Scott. On the other hand, he would immerse himself in certain works of Robert Browning or Thomas Hood. He admired their insight into macabre aberrations and the “morbid anatomy” in the personalities of men and women. If he read for pleasure, it would be with his pipe, a pouch of shag tobacco, and something like the Notable British Trials volume of Dr William Palmer, “The Rugeley Poisoner.”
He spent the journey to Sutton Cross dipping into several books which had been packed into his portmanteau. The subject-matter on such journeys was not designed to encourage conversation from our fellow passengers. In the past we had Maudsley on Insanity, Stevenson on Irritant Poisons, and on the most trying occasion of all, Krafft-Ebing’s Psychopathia Sexualis. Holmes had perused this volume unremittingly for two hours in a corner seat, opposite a rural dean returning to his Oxford-shire parish.
On this occasion, his choice was unexceptionable. From Liverpool Street to Cambridge, his attention was held by Shakespeare’s King John. Thereafter, he was absorbed by Professor Plucknett’s edition of Pipe Rolls of the Plantagenets. I knew only that these were official records of the reigns of Henry II or King John.
At King’s Lynn, we changed from the London express. A local train ran unevenly along the last few miles of the Norfolk coast and across the wide estuary of the Wash into Lincolnshire. It paused at every little platform and country halt, under the vast open skies of the fens and among the numerous marshes and waterways that ran everywhere. Here and there were glimpses of creamy breakers and a brown tide drawing away across long gleaming expanses of sand. Such was the North Sea or “The German Ocean,” as some people still called it.