My companion followed me upstairs rather reluctantly, I thought, passing the room where the mysterious tragedy had occurred and ascending to the floor above. There were four bedrooms, each well-furnished, but finding that they contained nothing of a suspicious character we continued to the top floor, where there were several smaller low-ceilinged rooms opening from a narrow passage. Two of them were evidently the sleeping apartments of the servants, the third was filled with lumber, but the fourth, which overlooked the back premises, long and narrow, was fitted as a kind of workshop or laboratory. A curious smell greeted our nostrils as we opened the door--a smell very much like the perfume on the dead woman's handkerchief. We found a gas-jet and lit it, afterwards gazing round the place with some surprise. Upon shelves around the walls were various bottles containing liquids; on the table stood two curious-looking globes of bright steel, riveted like those of a steam-boiler, and connected by a long tubular coil rolled into three consecutive spirals which ended with a kind of nozzle. From the fact that an electric battery and a lathe also stood in the room we at once came to the conclusion that the master of that house had been engaged in some scientific investigations. From place to place we went, searching every corner for any written document or letter, until at last I found, crumpled and cast into the empty grate, an old envelope on which I read the address: "Professor Douglas Dawson." "At any rate we've got the name of the occupant of this place," I said, handing my find to the police-officer. "Dawson?" he repeated, "Dawson? I fancy I've heard that name in connexion with scientific discovery." "I don't know," I said. "If he's a well-known man we shall soon find out all about him at the Royal Institution." I was standing near the fireplace with the envelope still in my hand when, of a sudden, I was startled by a strange scuttling noise near my feet. "Good heavens!" gasped Patterson, his eyes riveted on the spot. "Look there! Look at that glass case! There are snakes in it!" I sprang away, and looking in the direction he indicated saw that a glass case, standing on the ground, contained two great snakes with beautiful markings of yellow and black. Even as I looked they were coiled, with their flat heads erect and their bead-like eyes shining like tiny stars in the shadow, their bodies half-hidden in a blanket. "Nice kind of pets, to keep in a house," observed Patterson. "That's one of them that's escaped into the garden, I expect." "I quite agree," I said, "this place is decidedly the reverse of cheerful. Hadn't we better report at once? There's been a mysterious tragedy here, and immediate efforts should be made to trace the assassin." "But, my dear fellow, how do you know they've been murdered?" he argued. "There's no marks of violence whatever."