“A bullet lodged in the tree, I suspect.” Bell used Hodge’s knife to gouge the bark around the hole. He carved an opening large enough to dislodge a soft lead wad with his fingers in an effort not to scratch it with the blade.

“Where the heck did that come from?”

“Maybe Harry Frost’s rifle.”

“Maybe, maybe not. You’ll never know.”

“Maybe I will,” said Bell, recalling a court case argued a few years earlier by Oliver Wendell Holmes where a bullet was matched to the gun that fired it. “Do you happen to have that rifle the boys found on the tracks?”

“In my office. I’d have given it back to Mrs. Frost, but she left. Mr. Frost of course was long gone. Anyone left on the property out there is no one I would give a fine rifle to.”

They returned to North River. Hodge helped Bell find a bale of cotton wool packing material at the railroad depot. They set it up at the empty end of the freight yard. Bell stuck his calling card in the center of the bale and paced off one hundred and fifty yards. Then he loaded two .45-70 shells into Frost’s Marlin, found the calling card like a bull’s-eye in the telescopic sight, and squeezed off a round.

The bullet missed the card, missed the cotton wool bale, and twanged off an iron signal post above it.

Constable Hodge looked pityingly at Isaac Bell. “I naturally assumed that a Van Dorn private detective would be conversant with firearms. Would you like me to shoot it for you?”

“The scope is off-kilter.”

“That’ll happen,” Constable Hodge said, dubiously. “Sometimes.”

“It could have been damaged when it was dropped on the tracks.”

Bell sighted in on the mark the bullet had pocked in the iron post and calculated the distance down. He levered out the spent shell, which loaded a fresh cartridge into the chamber, and squeezed the trigger. His calling card flew from the bale.

“Now you’re getting the hang of it,” Hodge said. “Keep it up you could be a pretty good shot, young feller.”

Bell dug the bullet out of the bale and wrapped it in a handkerchief along with the slug he had pulled from tree. He walked to the post office and mailed them to the Van Dorn laboratory in Chicago, requesting examination under a microscope to determine whether the bullet he had test-fired revealed rifling marks that resembled those on the bullet in the tree.

“Is anyone living out at Frost’s camp?” he asked Hodge.

“No one you’d want to meet. About the only thing still going is the creamery. They send milk into town to sell. Cook, maids, butler, gardeners, and gatekeeper, they all left when Mrs. Frost did.”