"No boys with firecrackers playing around. It's the lull between the 17th of June and the Fourth."
"No phosphorescent rat-bane on the premises," went on McCausland, telling off finger after finger. "You heard what the domestic said?"
"Yes; she was positive about that."
"Because they were not troubled with mice. Another accidental cause removed. But if rodents were swarming like flies in a meat shop, I don't see what substance more combustible than the pasted bindings of old books they could have found in that library to nibble. The lucifers were all kept in a safe downstairs, excepting a few for the sleeping-rooms."
"That's true, but----"
"Number six," interrupted McCausland. "What shall it be? Cotton waste taking fire spontaneously? Benzine? Naphtha varnish? Celluloid? None of them about, according to Bertha. I'm at my rope's end. Where are you?"
"Do you suppose they have been as careful since the professor died?" asked the marshal.
"That was o