I glanced to the left where he had indicated, and saw that the good-sized brick furnace built in the right-hand wall, in which, by means of a great electric fan, the Professor could generate, by forced draught, the intense heat he sometimes required for his experiments, was aglow. A fierce fire had evidently been burning there, but it was now slowly dying out. The warmth of the laboratory and of the brickwork of the furnace showed that the draught fan must have been used.
“I wonder what the Professor has been doing to-day?” remarked the inspector, examining the place with considerable curiosity.
“I wonder rather what intruders have been doing here!” exclaimed Langton. “You forget that both doors have been forced.”
The inspector stood gazing round the place in silent wonder.
“Well,” he exclaimed at last, “I don’t see the slightest evidence of burglars here, sir.”
“They may be hidden upstairs,” suggested the young man. “Remember there are many people very anxious to obtain knowledge of the Professor’s discoveries. That is why he is always so careful to keep these doors locked. His daughter, Ethelwynn, is the only person he ever allows in here. He and she even carry in the coal for the furnace, the servants being excluded.”
“But thieves would hardly light up the furnace!” said the officer.
“Unless they wished to destroy something in the fire,” responded the other.
That suggestion held me aghast. Upon me, like a flash, came the astounding suspicion that that furnace might have been lit for the purpose of destroying the evidence of the mysterious crime. I remembered Kirk’s curious and guarded response when I had referred to the burial of the body.
Was this, then, the reason why I had found him alone in the house?