"Ah," he said, "you overdraw. The lesson has been easily acquired. Science is not an easy road to travel. Those who propose to profit thereby must work circuitously, soil their hands and person, meet discouragements, and must expect hardships, reverses, abuse, and discomfort. Do not complain, but thank me for giving you the lesson without other tribulations that might have accompanied it. Besides, there was another object in my journey, an object that I have quietly accomplished, and which you may never know. Come, we must return." He extinguished the light of the candle, and we departed together, trudging back through the mud and the night.[8] [8] We must acquiesce in the explanation given for this seemingly uncalled-for journey, and yet feel that it was unnecessarily exacting. Of that wearisome return trip I have nothing to say beyond the fact that before reaching home my companion disappeared in the darkness of a side street, and that the Cathedral chimes were playing for three o'clock A.M., as I passed the corner of Eighth Street and Western Row. The next evening my visitor appeared as usual, and realizing his complete victory, he made no reference to the occurrences of the previous night. In his usual calm and deliberate manner he produced the roll of manuscript saying benignantly, and in a gentle tone: "Do you recollect where I left off reading?" "You had reached that point in your narrative," I answered, "at which your guide had replaced the boat on the surface of the lake." And the mysterious being resumed his reading. THE MANUSCRIPT CONTINUED. CHAPTER XXXI. A LESSON ON VOLCANOES.--PRIMARY COLORS ARE CAPABLE OF FARTHER SUBDIVISION. "Get into the boat," said my eyeless pilot, "and we will proceed to the farther edge of the lake, over the barrier of which at great intervals of time, the surface water flows, and induces the convulsion known as Mount Epomeo." We accordingly embarked, and a gentle touch of the lever enabled us rapidly to skirt the shore of the underground sea. The soft, bright, pleasant earth-light continually enveloped us, and the absence of either excessive heat or cold, rendered existence delightful. The weird forms taken by the objects that successively presented themselves on the shore were a source of continual delight to my mind. The motion of our boat was constantly at the will of my guide. Now we would skim across a great bay, flashing from point to point; again we wound slowly through tortuous channels and among partly submerged stones. "What a blessing this mode of locomotion would be to humanity," I murmured.