"'Why?' I asked, stupidly.
"'Oh, dear—why, because we are invisible.'
"I tried to repress a shudder. The professor gave Wilhelmina his arm, and, as I studied his ensemble, I thanked Heaven that he was invisible.
"At the gate of the station I hailed a four-seated cab, and we rattled away through the stony streets, brilliant with gas-jets, and in a few moments rolled smoothly across the Avenue de l'Opéra, turned into the Rue de l'Échelle, and stopped. A bright little page, all over buttons, came out, took my luggage, and preceded us into the hallway.
"I, with Wilhelmina on my arm and the professor shuffling along beside me, walked over to the desk.
"'Room?' said the clerk. 'We have a very desirable room on the second, fronting the Rue St. Honoré—'
"'But we—that is, I want three rooms—three separate rooms!' I said.
"The clerk scratched his chin. 'Monsieur is expecting friends?'
"'Say yes,' whispered Wilhelmina, with a suspicion of laughter in her voice.
"'Yes,' I repeated, feebly.