"Now I will draw a figure in which one pocket is above the other, and ask you to imagine that in the lower pocket we have pure water, in the upper pocket brine (Figure 14); can you bring any theory of your law to bear upon these liquids so that by connecting them together the water will rise and run into the brine?" [Illustration: FIG. 14.--B, brine. W, water. S, sand stratum. (The difference in altitude is somewhat exaggerated to make the phenomenon clear. A syphon may result under such circumstances.--L.)] "No," I replied; "connect them, and then the brine will flow into the water." "Upon the contrary," he said; "connect them, as innumerable cavities in the earth are joined, and the water will flow into the brine." "The assertion is opposed to applied philosophy and common sense," I said. "Where ignorance is bliss, 'tis folly to be wise, you know to be a maxim with mortals," he replied; "but I must pardon you; your dogmatic education narrows your judgment. I now will prove you in error." He took from his pocket two slender glass tubes, about an eighth of an inch in bore and four inches in length, each closed at one end, and stood them in a perforated cork that he placed upon the table. Into one tube he poured water, and then dissolving some salt in a cup, poured brine into the other, filling both nearly to the top (Figure 15). Next he produced a short curved glass tube, to each end of which was attached a strip of flexible rubber tubing. Then, from a piece of blotting paper such as is used to blot ink, he cut a narrow strip and passed it through the arrangement, forming the apparatus represented by Figure 16. [Illustration: FIG. 15. A A, glass tubes. F, brine surface. E, water surface.] [Illustration: FIG. 16. B, curved glass tube. C C, rubber tubes. D D D, bibulous paper.] Then he inserted the two tubes (Figure 15) into the rubber, the extremities of the paper being submerged in the liquids, producing a combination that rested upright in the cork as shown by Figure 17. The surfaces of both liquids were at once lowered by reason of the suction of the bibulous paper, the water decreasing most rapidly, and soon the creeping liquids met by absorption in the paper, the point of contact, as the liquids met, being plainly discernible. Now the old man gently slid the tubes upon each other, raising one a little, so as to bring the surfaces of the two liquids exactly on a plane; he then marked the glass at the surface of each with a pen. "Observe the result," he remarked as he replaced the tubes in the cork with their liquid surfaces on a line. Together we sat and watched, and soon it became apparent that the surface of the water had decreased in height as compared with that of the brine. By fixing my gaze on the ink mark on the glass I also observed that the brine in the opposing tube was rising. "I will call to-morrow evening," he said, "and we shall then discover which is true, man's theory or nature's practice."