The workman crumpled to the floor, a little thread of blood creeping from his right temple.
It was the thing upon which Dick looked back afterward with less satisfaction than any other, leaving the two unconscious men in that room of death. Yet there was nothing else he could have done. He ran to the trap, and saw a ladder leading down. In a moment he had swung himself through and closed the trap behind him.
The material that lined the walls below must have had almost perfect insulating qualities, for the temperature here was no hotter than in the Bahamas on a hot summer day. Dick scrambled down the ladder and found himself in a machine-shop. Nobody was there, and tools of all sorts were lying about, as well as machinery whose purpose he did not understand. A pair of heavy pliers and a vise were sufficient to rid Dick of his wrist and ankle chains in a minute or two. With a knife he slashed the cords of invisible stuff that bound him. He stood up, cramped, but free.
He picked up an iron bar that was lying loose on a table beside a machine, and advanced to the staircase in one corner of the shop. As he approached it, another workman came running up.
ick stood aside in an embrasure in the wall partly occupied by a machine. The man passed within two feet of him and never saw him. Only then did Dick quite realize that he was actually invisible.
The moment the man had passed him, Dick ran to the staircase. He descended one flight; he was half way down another when a yell of pain and imprecation came to his ears. He knew that voice: it was Luke Evans's!
With three bounds Dick reached the bottom of the stairs. He saw a large room in front of him. No mistaking the nature of this room; it was an ordinary laboratory, fitted out with the greatest elaboration, and divided into two parts by paneling. And sight and sound were on.
In the part nearer Dick three men were grouped about a large dynamo, which was sending out a high, musical note as it spun. Levers and dials were all about it, and above it was the base of the glass tube that Dick had seen above. In the other part were five or six men. Three of them were testing some substance at a table; three more were gathered about old Luke Evans, whose silver chains had been removed and replaced by ropes, which bound his limbs, and also bound him to a heavy chair, which seemed to be affixed to the ground. One of the three had a piece of metal in a pair of long-handled pliers. It was white hot, and a white electric spark that shot to and fro between two terminals close by, showed where it had been heated.