"If that isn't thermite, I'm a Dutchman," he said. "At any rate, we'll be able to convict Mr. Milburgh of arson if we can't get him for murder. We'll send this to the Government analyst right away, Whiteside. If Milburgh did not kill Thornton Lyne, he certainly burnt down the premises of Dashwood and Solomon to destroy the evidence of his theft."
It was Whiteside who made the second discovery. Mr. Milburgh slept on a large wooden four-poster.
"He's a luxurious devil," said Whiteside. "Look at the thickness of those box springs." He tapped the side of that piece of furniture and looked round with a startled expression.
"A bit solid for a box spring, isn't it?" he asked, and continued his investigation, tearing down the bed valance.
Presently he was rewarded by finding a small eyelet hole in the side of the mattress. He took out his knife, opened the pipe cleaner, and pressed the narrow blade into the aperture. There was a click and two doors, ludicrously like the doors which deaden the volume of gramophone music, flew open.
Whiteside put in his hand and pulled something out.
"Books," he said disappointedly. Then, brightening up. "They are diaries; I wonder if the beggar kept a diary?"
He piled the little volumes on the bed and Tarling took one and turned the leaves.
"Thornton Lyne's diary," he said. "This may be useful."
One of the volumes was locked. It was the newest of the books, and evidently an attempt had been made to force the lock, for the hasp was badly wrenched. Mr. Milburgh had, in fact, made such an attempt, but as he was engaged in a systematic study of the diaries from the beginning he had eventually put aside the last volume after an unsuccessful effort to break the fastening.