"If anything occurs," he said, taking my hand in his left and Miss Barrison's hand in his right, "promise me to obey my wishes. Will you?"
"Yes," we said, together.
"If I lose my life, or—or disappear, promise me on your honor to get to the electric launch as soon as possible and make all speed northward, placing my private papers, the reports of Miss Barrison, and your own reports in the hands of the authorities in Bronx Park. Don't attempt to aid me; don't delay to search for me. Do you promise?"
"Yes," we breathed together.
He looked at us solemnly. "If you fail me, you betray me," he said.
We swore obedience.
"Then let us begin," he said, and he rose and went to the steel cage. Unlocking the door, he flung it wide and stepped inside, leaving the cage door open.
"The moment a single pie is disturbed," he said to me, "I shall close the steel door from the inside, and you and Miss Barrison will then dump the rosium oxide and the strontium into the tank, clap on the lid, turn the nozzle of the hose on the cage, and spray it thoroughly. Whatever is invisible in the cage will become visible and of a faint rose color. And when the trapped creature becomes visible, hold yourselves ready to aid me as long as I am able to give you orders. After that either all will go well or all will go otherwise, and you must run for the launch." He seated himself in the cage near the open door.
I placed the steel tank near the cage, uncoiled the hose attachment, unscrewed the top, and dumped in the salts of strontium. Miss Barrison unwrapped the bottle of rosium oxide and loosened the cork. We examined this pearl-and-pink powder and shook it up so that it might run out quickly. Then Miss Barrison sat down, and presently became absorbed in a stenographic report of the proceedings up to date.
When Miss Barrison finished her report she handed me the bundle of papers. I stowed them away in my wallet, and we sat down together beside the tank.