science has not yet explained everything.â
âAnd among those unexplained things you count magic umbrellas and clouds of mist with the power to dematerialise a ship?â
Holmes pulled up his legs into his armchair and peered dreamily into the fire. I enjoyed my cigar in silence for a few minutes, meanwhile picking up one of the newspapers that Holmes had opened on the item that described the Alicia affair. There was a picture of Jack Frome accompanying the article, a gentle-looking face framed by a thick chinstrap beard, and I began to contemplate it, musing on this man and his predicament.
âYou say that Mr Frome appeared agitated and uneasy when he came to you?â I asked Holmes.
âYes, and he complained of headaches. But he dismissed my expressions of sympathy, saying that he had regularly occurring headaches and that they usually went away after a while.â
âWas it anything more than headaches?â
âWhat do you mean?â
âI was only reminded of an article I read a few years back about a French physician who described a condition that I have encountered in some of my own patients. It connects migraine headaches with distorted vision or even a loss of vision in one eye.â
âYou interest me, Watson. Go on.â
âWell, there is no mystery about it. The phenomenon is commonly linked to cerebral disturbances, and a decreased arterial blood flow is the probable cause of these distortions, which the medical men term âaurasâ. In some it presents itself like zigzagging lines across the field of vision, in some a blurring of the sight on one eye, and in some rare cases a complete loss of sight on one eye.â
Holmes looked at me as if frozen stiff. He did not move a muscle for what must have been twenty seconds. Then I could see his eyes moving about as if he was letting his gaze scan across an invisible book in front of him. Finally he rose from his armchair and walked up to the nearest bookcase, from which he took down a folio-sized binder. He carried it to the table, pushed away some of the chemical instruments and placed it there. Untying the ribbon that held the covers of the binder together, he opened it, and I could see that it contained a large bundle of maps. Sea charts, to be exact. Flipping through them, Holmes was clearly searching for one in particular, and when he found it, he made a loud victorious cry.
âYes, yes, it all fits together. Splendid, my boy! As I have said on numerous occasions, you are a conductor of light. But this time, Watson, you excel yourself. I must admit that you have cracked it, and I am very much in your debt.â
âCracked it? Surely not. A mere sight loss cannot account for the disappearance of an entire ship and its crew!â
âNot on its own, of course, but taken together with the fact that only Frome was following the cutter with his eyes the whole way, and that the patch of mist in all likelihood was not static, but drifted some yards to the side before it cleared away, it is all perfectly obvious. Here, look at this chart of the waters outside Lydmouth. Do you see? Just southeast of Lydmouth is a small group of islands, barely visible from land but close enough to allow a small boat to sail there in a matter of minutes. Now, the waters around here are treacherous, Frome said so himself, and if the conditions are just right, then it is perfectly possible for the Alicia to have sailed into the mist, lost its bearings - a small cutter like that has no need for any advanced navigational instruments - and followed along with the patch of mist to the east. Thus, it would have drifted to the left from Fromeâs point of view, and if it is as you indicated, that he suffered from a blurred field of vision in advance of the migraine headache that he received the next day when he came to see me, then it is likely that he had no view of it. And once the mist cleared away, the cutter, going in the