John Adams - The Improbable Adventures of Sherlock Holmes

"What do you plan to do with your future, Arthur?" I asked.

"Surgery, sir," said Arthur. "I'm very much inspired by Doctor Bell at the Edinburgh University. But I'd also like to become a writer like you, actually, and have written some stories for Reginald's children. Edgar Allan Poe's another inspiration, and I'm attempting a mystery now."

"Poe! Now there was a true Copernican. I heard he was a great cryptographer," I said.

Moriarty disagreed. "He indulged in substitution codes, barely worth the effort to solve, unlike Vigenère ciphers."

Arthur asked what a Vigenère cipher was.

"It's based on the Caesar cipher, which shifted letters by a chosen number of positions, looping back to the beginning of the alphabet if necessary," I explained. "Shift the word JABBERWOCKY four positions to the right, you'd have NEFFIVSGOC. To solve the coded message, apply the shift in reverse.

"The Vigenère cipher uses a keyword where each letter in the alphabet represented a different shift. For example, if ALICE were my keyword, that would mean shifts of 0, 11, 8, 2, and 5. The keyword is repeated as needed, and so JABBERWOCKY becomes JLJDIRHWEOY."

Moriarty nodded. "There are mathematical ways to solve a Vigenère code. Kasiski's method determines the length of the keyword by measuring distances between repeating combinations, then uses frequency analysis to break the code. Kerckhoffs' method focuses on solving the keyword itself."

"Moriarty, didn't you have a notebook at Christ Church where you jotted down your formulae?" I asked. "You used a cipher on the annotations. Was that Vigenère?"

Moriarty smiled. "It was, to ensure that the musings and errors of my youth were for my eyes alone. But I'm confident that my code cannot be broken by either the Kerckhoffs or Kasiski solutions. They assume the keyword would be short, and repeated. But if the keyword's significantly long, like a piece of text, then a coded message would be virtually unbreakable."

"Respectfully, Professor, the keyword may be impervious to analysis, but the codemaker is not," said Arthur. "At medical school, Professor Bell taught us to observe the person as well as the disease in our diagnoses. By analyzing the man's habits, experiences and indulgences, one can deduce the choice of text he uses for his code."

"You presume to unriddle my cipher by mere observation?" asked Moriarty.

"If I had the chance to get to know you better, Professor, I daresay I could figure out your code," said Arthur.

"I know a challenge when I hear one! Reginald, indulge me by releasing Arthur from his obligations on weekends. My university's not far, and I will pay for travel and lodging. He may observe me in my element, while I in turn will mentor him and provide him with a sample of cipher to unriddle. If he succeeds by summer's end, I will pay his tuition."

Moriarty had obviously taken a liking to Arthur Doyle, perhaps eager to guide a young man into his genius.

Reginald heartily agreed. "If he doesn't fall behind his duties here, why not?"

Arthur smiled. "It will be a pleasure learning from you, Professor."

"Before I forget, gentlemen, Samuel Haughton left these for you on his last visit," Reginald said, giving us each a copy of a treatise titled On Hanging. Reverend Haughton was a doctor and fellow Copernican from Dublin who dabbled in mathematics. "Haughton claims the mathematics of hanging can be useful in medicine. Humane versus inhumane hangings: depending on the criminal's weight and the length of drop, it could mean the difference between a quick death from snapping his spinal cord, to a long death from strangulation."

We argued awhile over the need for executions, with Moriarty maintaining ambivalence. When the topic somehow drifted onto the three-body problem in astronomy, which I had little interest in, Arthur and I excused ourselves so I could see his story manuscripts.

Arthur's room was modest, and his desk cluttered with papers on medicine, scraps of writing, and sheet music. Among his medical books were works by Burton, Dickens, Leibniz, and of course, Poe. He moved a violin case off a chair so I could sit and read his stories. I found them well-written and engaging, and encouraged Arthur to continue writing.

Arthur retrieved a book bound in red Moroccan leather, gilt in silver: a copy of Alice's Adventures in Wonderland. "Would you mind signing this, Reverend, for Herr Gleiwitz? I see him on my rounds, and feel sorry for the man. He's down on his luck, raising his children on what little income he receives from giving German lessons. Perhaps your book will give his family some joy."

I gladly signed the copy.

Arthur wrote to me at Oxford thereafter, telling me of his tutelage under Moriarty. At first, his letters were ebullient, saying that the Professor's cunning rivaled that of Doctor Bell's. Whereas Bell emphasized observation, Moriarty taught him anticipation. Predicting behaviour was as crucial as establishing history, he wrote, explaining Moriarty's philosophy. The world was a chessboard and men were as predictable as game pieces.

But Arthur's later letters were sombre, hinting at a rift between himself and Moriarty. Did Moriarty's enthusiasm for his student turn to envy? Or did Arthur discover Moriarty's dark dealings? In any event, it spelled death for him.

In late summer, both Moriarty and I accepted an invitation from a fellow Copernican in London. On our third night there, upon our return from the symphony, we learned by telegram that tragedy had struck: Arthur Doyle was found dead, hanged.

"Arthur had been concerned about matters in Aston, but refused to say more," said Moriarty, stunned by the news. "I ought to have foreseen disaster."

I consoled him. "How could you have known?"

"We owe it to the boy to investigate his death, Charles," he insisted.

And so Moriarty and I returned to Aston, bearing our condolences to Reginald.

Reginald recounted the details of Arthur's death. "Arthur had returned from house calls and retired to his room that evening as usual. The following morning, we were shocked to hear Arthur had been found in the bell tower at St. Mary's, the church down the street. Inspector Ives took me there to identify Arthur's body."

"Cause of death?" asked Moriarty.

"All the signs pointed towards asphyxiation. Inspector Ives believes it was suicide," said Reginald.

"Arthur would hardly take his own life," said Moriarty. "Reginald, come with us and describe what you saw?"

Reluctantly, the good doctor accompanied us to St. Mary's. The bell tower was several stories tall, with a ladder up to a trapdoor that led into the belfry. The bell's rope dangled through a large opening in the belfry floor.

"The noose was tied to the bell's gudgeon," explained Reginald. "He was dangling six feet off the ground when we found him. He couldn't have kicked away a support, or we'd have discovered one. He must have jumped from the bell chamber."

"He could have pushed off the ladder," observed Moriarty. "But the momentum might have swung his body into the wall opposite. Any bruising on his arms or legs?"

"No," said Reginald.

"A dying man's instinct is to claw at the noose, even if he intended to die. Did you find any scratch marks around his neck?" continued Moriarty.

"No."

"But his hands weren't bound?"

"Correct."

"Then the evidence points towards a sudden drop from above," said Moriarty. "Except that's impossible."

"Why?" asked Reginald, perplexed.

"Mathematics," I explained, remembering Haughton's treatise on hanging. "Given his weight, a rope that exceeded twelve feet would make the force of the drop so great that the noose wouldn't simply snap his neck, it would cut clean through."

Moriarty nodded. "Given the marks on his neck, where was the noose's knot placed, Reginald?"