Slowly the conviction was forced on me. The man was mad—raving mad!
"Really, I must get back to the city tonight," I overheard Craig say to the Señorita as finally he turned from the window toward us.
Her face clouded, but she said nothing.
"If you could arrange to have us dine with you tomorrow night up here, however," he added quickly in a whisper, "I think I might be prepared to take some action."
"By all means," she replied eagerly, as though catching at anything that promised aid.
On the late train back, I half dozed, wondering what had caused Mendoza's evident madness. Was it a sort of auto-hypnotism? There was, I knew, a form of illusion known as ophthalmophobia—fear of the eye. It ranged from mere aversion at being gazed at, all the way to the subjective development of real physical illness out of otherwise trifling ailments. If not that, what object could there be for anyone to cause such a condition? Might it be for the purpose of robbery? Or might it be for revenge?
Back in the laboratory, Kennedy pulled out from a cabinet a peculiar apparatus. It seemed to consist of a sort of triangular prism set with its edge vertically on a rigid platform attached to a massive stand.
Next he lighted one of the cigarette stubs which he had carried away so carefully. The smoke curled up between a powerful light and the peculiar instrument, while Craig peered through a lens, manipulating the thing with exhaustless patience and skill.
Finally he beckoned me over and I looked through, too. On a sort of fine grating all I could see was a number of strange lines.
"That," he explained in answer to my unspoken question as I continued to gaze, "is one of the latest forms of the spectroscope, known as the interferometer, with delicately ruled gratings in which power to resolve the straight close lines in the spectrum is carried to the limit of possibility. A small watch is delicate, but it bears no comparison to the delicacy of these detraction spectroscopes.