human
It turned out, though, that Denny spoiled a nice trap they'd laid up at Tarrytown to catch those fellows when they got there. You see, the telegraph operator wired up the line that a runaway locomotive was coming with three escaped convicts on her, and the train despatcher at Tarrytown just set the switch so the locomotive would sail plump over a twelve-foot stone embankment down into the Hudson River. That's what would have happened to those convicts if Denny had left his tank-valves alone, but, of course, 89 got water-logged long before she reached Tarrytown; she just kicked out her cylinder-ends a few miles up the track and stopped. Then the convicts climbed down and skipped away. Two of 'em got caught afterward, but there was one they never caught.