paratus down in a special room in the basement. I saw it, but I had no idea what it was or what its use might be.
Close to the wall was a stereopticon which shot a beam of light through a tube to which I heard them refer as a galvanometer, about three feet distant. In front of this beam whirled a five-spindled wheel, governed by a chronometer which erred only a second a day. Between the poles of the galvanometer was stretched a slender thread of fused quartz plated with silver, only one one-thousandth of a millimetre in diameter, so tenuous that it could not be seen except in a bright light. It was a thread so slender that it might have been spun by a miscroscopic spider.
Three feet farther away was a camera with a moving film of sensitised material, the turning of which was regulated by a little flywheel. The beam of light focused on the thread in the galvanometer passed to the photographic film, intercepted only by the five spindles of the wheel, which turned once a second, thus marking the picture off into exact fifths of a second. The vibrations of the microscopic quartz thread were enormously magnified on the sensitive film by a lens and resulted in producing a long zigzag, wavy line. The whole was shielded by a wooden hood which permitted no light, except the slender ray, to strike it. The film revolved slowly across the field, its speed regulated by the flywheel, and all moved by an electric motor.
I was quite surprised, then, when Kennedy told me that the final tests which he was arranging were not to be held at the hospital at all, but in his labor-
