the other end of the valley by the other men in the intervals of their more important work. That work, however, you cannot understand until you become better acquainted with us.” We had now reached the platform, and we saw the men at work just as we had seen them the day before. Signor Davelli uttered a single word which I did not understand, and on hearing it the men turned, and then followed for a very few minutes the same sort of pantomimic action which I had already seen and have described. Then they resumed work. Signor Davelli then took us to the works and invited us to observe the construction of the various machines in use. I must not, however, run the risk of tiring you by any minute account of them here. Let it suffice to say that there was a much higher degree of mechanical skill exhibited in their construction than I have ever seen anywhere before or since, and that besides there was much that suggested the application of chemical and electrical science in a manner greatly in advance of anything that is commonly known; and further that there were certain complicated arrangements of prisms and mirrors which indicated as I thought some use of the agency of light which was quite new to me and which I did not understand. One set of machines proved to be used for the manufacture of the compressed food which we had already found so effective. Another set of much simpler construction carried it away and stored it when made. Yet another set was used for the manufacture of that invisible paint, the use of which had so astonished me. These last were the machines which attracted my curiosity most of all, and which implied not only a use which I did not comprehend of agencies which I recognised, but the existence of other agencies of which I knew nothing at all. I observed, however, as carefully as possible and I made, later on, very full notes of what I did observe, and I shall be happy to communicate these to our men of science in whose hands they can hardly fail to become of much practical value. I need hardly say that I asked a good many questions about this last set of machines, but somehow I got very little information. Whether Signor Davelli was unwilling to explain, or whether there was something in the process which I 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.