He stood for a few moments more, his fascination for the unbelievable shadow holding him there; then he swung away and went over to the work-bench, where he lit a lamp and began to thumb swiftly through a group of the old books lying carelessly abandoned there. Tenny followed, asking, "Can I help?" The older man nodded. "Check up on all references to magical designs in these books," he said. "I've got an idea. I don't know what's in it, but it's worth trying." It was Follansbee who found what they sought. "Here it is," he said suddenly. "Magical designs on glass. It's been marked up by someone, too--Kroll, most likely. Parts of it are illegible, but the sense of it can be made out. Third paragraph down in the second column." Tenny bent to read the printed lines on the yellow page: "Certain mages have brought into being worlds of glass--invisible in glass, the objects of such consistency that though they cannot be seen in the light of the sun, they are shadowed by the moon.... The glass is of no ordinary kind, but must be specially made. And the creatures to be placed there may be drawn from the mind or from life." "You see?" cut in Follansbee, drawing the book away. "That's what he was doing--but something happened. He tried it on himself, and vanished." Tenny turned astonished eyes on the glass in the window. Follansbee abruptly left the work-bench and, going over to the window, raised it. "It's the upper pane we want," he murmured. "It must be broken--there's no other way. But be careful that all the pieces fall into the room." As he spoke, the older man pulled down the upper half of the window. Then he drew the curtain down outside the glass, and into the room again below. "All right," he said. "Break it, Fred." Tenny rapped sharply against the glass of the upper pane. It did not break. He struck it harder with the trident from the work-bench. Still it did not break. Then he smashed into it with all his strength. The glass broke into incredibly small fragments that slithered down the drawn curtain to the floor. Follansbee let the curtain snap up. Looking down, he and Tenny exclaimed simultaneously. The window lay in silver fragments on the carpet in the moonlight that stretched to the bed--but beyond the fragments ran a tiny dark shadow, of substance now. "Good God!" breathed Follansbee hoarsely. "_The dimensions didn't change!_" "It's Kroll," said Tenny. He swooped to seize hold of the figure on the carpet, but at that moment it disappeared under the bed. He sank to his knees. "Kroll!" he shouted. "Come out, Kroll!" There was a vague scuttering noise beneath the bed. Follansbee came to his knees at Tenny's side and peered into the moonlit dusk beneath the bed. "Kroll" he whispered softly. Turning abruptly, he said to Tenny, "Get over on the other side. He's skirting the wall toward the door." Tenny moved to obey.