And so we resumed our climb. We were the early birds this morning; not a living soul was to be seen anywhere on the mountain. But hark! What was that? Somebody whistling somewhere up there and off to the right. The whistles came in rapid succession, and they were loud and clear and ringing. I stopped and looked but could see nothing. I should have explained that we had turned aside from the edge of the cañon, had crossed that little stream mentioned by grandfather Scranton and had begun to climb that steep rocky mass that he spoke of. "What the deuce," said I, "is that fellow whistling like that for? It can't be to us." "That," Milton Rhodes smiled, "isn't a man, Bill." "Not a man?" "It's a marmot," Milton told me. "A marmot? Well," said I, "we live and we learn. I could have sworn, Milton, that it was a human being." The ascent was a steep one, and we climbed in silence. The horse-trail, coming from the left, goes slanting and then twisting its way up this rocky rampart. On reaching the path, we paused for some moments to get our breath, then plodded on. "I was thinking," said Milton Rhodes at last, "of what Francis Parkman said." "What did he say?" "'I would go farther for one look into the crater of Vesuvius than to see all the ruined temples in Italy.'" "I wonder," I returned, "how far we shall have to go to see that angel that says Drome, not to mention her pretty demon." Rhodes laughed. "We are getting there, Bill; we're getting there--near the scene of the tragedies at any rate." Ere long we reached the top. Here we passed the last shrub and in a little space came to a small glacier. The tracks of the horses led straight across it. But our route did not go thither; it led up over the rocks. Suddenly, as we toiled our way upward, Rhodes, with the remark that Science had some strange stories to tell, asked me if I had ever heard of Tartaglia's _slates_. I never had, though I had heard of Tartaglia, and I wanted to know about those slates. "Tombstones," said Milton. "Tombstones?" "Tombstones, Bill. What with the terrible poverty, Tartaglia, when educating himself, could not get even a slate, and so he went out and wrote his exercises on tombstones." "Gosh!" "And did you ever hear of Demoivre's death? There is a problem for your psychological sharks." "I never heard of him. And how did the gentleman die?" "He told them that he had to sleep so many minutes longer each day." "And did he do it?" "That's what he did, Bill." "And," I asked with growing curiosity, "when he had slept through the twenty-four hours? Then what?" "He never woke up," said Milton Rhodes. Then he told me that queer story about Isaac Barrow, or, rather, about his father. When sent to school, at Charter-house, young Barrow raised the very deuce and raised it high; so much deuce, in fact, that dad Barrow, whilst praying, said that, if it should be the Divine pleasure to take from him any of his children, he could best stand the loss of Isaac.