At length he looked up, and, addressing the inspector, asked: “Do you know what felt hats are made of?”
“I can’t say that I do, sir,” replied the officer.
“Well, the better quality hats are made of rabbits’ and hares’ wool—the soft under-fur, you know—cemented together with shellac. Now there is very little doubt that these cinders contain shellac, and with the microscope I find a number of small hairs of a rabbit. I have, therefore, little hesitation in saying that these cinders are the remains of a hard felt hat; and, as the hairs do not appear to be dyed, I should say it was a grey hat.”
At this moment our conclave was interrupted by hurried footsteps on the garden path and, as we turned with one accord, an elderly woman burst into the room.
She stood for a moment in mute astonishment, and then, looking from one to the other, demanded: “Who are you? and what are you doing here?”
The inspector rose. “I am a police officer, madam,” said he. “I can’t give you any further information just now, but, if you will excuse me asking, who are you?”
“I am Mr. Hickler’s housekeeper,” she replied.
“And Mr. Hickler; are you expecting him home shortly?”
“No, I am not,” was the curt reply. “Mr. Hickler is away from home just now. He left this evening by the boat train.”
“For Amsterdam?” asked Thorndyke.