“Why did you leave?  Why go over to McCann’s in business hours?”

“We’d worked until after midnight the night before.  I had to open up early and so I figured I’d have my breakfast in the usual morning slack time—­when nothing’s doing.”

“I see!” Kennedy studied the ground for several moments.  “Do you suppose anyone could have left a package in there—­a bomb, in other words?”

Wagnalls’s eyes widened, but he shook his head.  “I’d notice it, sir!  If I do say it, I’m neat.  I generally notice if a can has been touched.  They don’t often fool me.”

“Well, has any regular stuff been brought to you to put away; anything which might have hidden an explosive?”

Again Wagnalls shook his head.  “I put nothing away or give nothing out except on written order from Mr. Manton.  Anything coming in is negative and it’s in rolls, and I rehandle them because they’re put away in the flat boxes.  I’d know in a minute if a roll was phony.”

“You’re sure nothing special—­”

“Holy Jehoshaphat!” interrupted Wagnalls.  “I’d forgotten!” He faced Manton.  “Remember that can of undeveloped stuff, a two-hundred roll?” He turned to Kennedy, explaining.  “When negative’s undeveloped we keep it in taped cans.  Take off the tape and you spoil it—­the light, you know.  Mr. Manton sent down this can with a regular order, marking on it that some one had to come to watch it being developed—­in about a week.  Of course I didn’t open the can or look in it.  I put it up on top of a rack.”

“When was this?”

“About four days ago—­the day Miss Lamar was killed.”

The expression on Manton’s face was ghastly.  “I didn’t send down any can to you, Wagnalls,” he insisted.

“It was your writing, sir!”

Kennedy rose.  “What did you do with orders like that, such as the one you claim came with the can of undeveloped negative?”

“Put them on the spindle on that table in the vault.”

“Wet your handkerchief and come show me.”

When they returned Kennedy had the spindle in his hand, the charred papers still in place.  This was one of the items preserved in part by the chemical spray through the ventilating opening above.

“Can you point out which one it is?” Kennedy asked.

“Let’s see!” Wagnalls scratched his head.  “Next to the top,” he replied, in a moment.  “Miss Lamar’s death upset everything.  Only one order came down after that.”

With extreme care Kennedy took his knife and lifted the ashy flakes of the top order.  “Get me some collodion, somebody!” he exclaimed.

Wagnalls jumped up and hurried off.

The fire chief leaned forward.  “Do you think, Mr. Kennedy, that the little can he told you about started the fire?”

“I’m sure of it, although I’ll never be able to prove it.”

“How did it work?”