was incapable of understanding, I am not quite sure. All I could get from him was that there are some rays at either end of the spectrum which are not visible, and that it is possible to treat some substances so as to cause them to reflect these rays only, just as other substances reflect only the yellow or only the red. But from a word or two which he spoke, I suspect inadvertently, I gathered that the rays he spoke of, which are invisible to us, were visible to him, and differed as much from yellow, red, or blue, as these from one another.
We now crossed the platform to the place where the cars were being painted. I perceived as soon as I came upon the spot that the cars were built at one level, and then raised by machinery to another level at which they were painted, and that when painted they were raised to a third level. Along each of these levels they were moved by rollers of quite simple construction. Yesterday I had only seen those on the second level; those on the first were too low to come within the field of my view, and those on the third were invisible.
On this third level, however, one was to-day visible. As I afterwards learned, Signor Davelli had caused it to be left unpainted. It was otherwise finished. He caused it now to be rolled along to the extremity of
