He drew a red line down Broadway, then pointed to the small square it bordered. “Thus, it seems reasonable to assume that our Dr. Leng lived west of this line, no more than one block from the Hudson.”
He capped the marker, then glanced back at Nora and O’Shaughnessy. “Any comments so far?”
“Yes,” said Nora. “You said Clark & Sons delivered coal to this area uptown. But why was this coal found downtown in his laboratory?”
“Leng ran his laboratory in secret. He couldn’t have coal delivered there. So he would have brought small amounts of coal down from his house.”
“I see.”
Pendergast continued to scrutinize her. “Anything else?”
The room was silent.
“Then we can assume our Dr. Leng lived on Riverside Drive between 110th Street and 139th Street, or on one of the side streets between Broadway and Riverside Drive. That is where we must concentrate our search.”
“You’re still talking hundreds, maybe thousands, of apartment buildings,” said O’Shaughnessy.
“Thirteen hundred and five, to be exact. Which brings me to the glassware.”
Pendergast silently took another turn around the table, then reached out and picked up a fragment of glass with a pair of rubber-tipped tweezers, holding it into the light.
“I analyzed the residue on this glass. It had been carefully washed, but with modern methods one can detect substances down to parts per trillion. There was a very curious mix of chemicals on this glassware. I found similar chemicals on the glass bits I recovered from the floor of the charnel. Quite a frightening mixture, when you begin to break it down. And there was one rare organic chemical, 1,2 alumino phosphocyanate, the ingredients for which could only be purchased in five chemists’ shops in Manhattan at the time, between 1890 and 1918, when Leng appears to have used his downtown laboratory. Sergeant O’Shaughnessy was most helpful in tracking down their locations.”
He made five dots on the map with his marker.
“Let us first assume Dr. Leng purchased his chemicals at the most convenient place. As you can see, there is no shop near his lab downtown, so let us postulate he purchased his chemicals near his house uptown. We can thus eliminate these two East Side shops. That leaves three on the West Side. But this one is too far downtown, so we can eliminate it as well.” He made crosses through three of the five dots. “That leaves these two others. The question is, which one?”
Once again, his question was greeted by silence. Pendergast laid down the piece of glass and circled the table yet again, then stopped in front of the map. “He shopped at neither one.”
He paused. “Because 1,2 alumino phosphocyanate is a dangerous poison. A person buying it might attract attention. So let us assume, instead, that he shopped at the chemist farthest from his haunts: his house, the Museum, the downtown lab. A place where he would not be recognized. Clearly, that has to be this one, here, on East Twelfth Street. New Amsterdam Chemists.” He drew a line around the dot. “This is where Leng shopped for his chemicals.”
Pendergast spun around, pacing back and forth before the map. “In a stroke of good fortune, it turns out New Amsterdam Chemists is still in business. There may be records, even be some residual memory.” He turned to O’Shaughnessy. “I will ask you to investigate. Visit the establishment, and check their old records. Then search for old people who grew up in the neighborhood, if necessary. Treat it as you would a police investigation.”
“Yes, sir.”
There was a brief silence. Then Pendergast spoke again.
“I’m convinced Dr. Leng didn’t live on any of the side streets between Broadway and Riverside Drive. He lived on Riverside Drive itself. That would narrow things down from over a thousand buildings to less than a hundred.”
O’Shaughnessy stared at him. “How do you know Leng lived on the Drive?”
“The grand houses were all along Riverside Drive. You can still see them, mostly broken up into tiny apartments or abandoned now, but they’re still there—some of them, anyway. Do you really think Leng would have lived on a side street, in middle-class housing? This man had a great deal of money. I’ve been thinking about it for some time. He wouldn’t want a place that could be walled in by future construction. He’d want light, a healthy flow of fresh air, and a pleasant view of the river. A view that could never be obstructed. I know he would.”
“But how do you know?” O’Shaughnessy asked.
Suddenly, Nora understood. “Because he expected to be there for a very, very long time.”
There was a long silence in the cool, spacious room. A slow, and very uncharacteristic, smile gathered on Pendergast’s face. “Bravo,” he said.
He went to the map, and drew a red line down Riverside Drive, from 139th Street to 110th. “Here is where we must look for Dr. Leng.”
There was an abrupt, uncomfortable silence.
“You mean, Dr. Leng’s house,” said O’Shaughnessy.
“No,” said Pendergast, speaking very deliberately. “I mean Dr. Leng.”
Horse’s Tail
ONE