Reaching another flat level we ran into the mountain station of Zanjou Amarillo. Here were engine sheds, for it is necessary to change the engine at this place. We dismounted from the "cow-catcher," and, shivering with the cold, watched a heavy black engine attached. From this point until the other side of the Andes is reached part of the way is covered by the use of a rack rail. The railway is too steep for an ordinary engine to climb. Accordingly, in the centre is a third line with cogs. The engine has an extra wheel with cogs, so that it does not run but grips its way to further heights. [Illustration: THE HOTEL AT INCA.] The day was bright. Through clefts in our shut-in way we could see snow on the mountains. We travelled up a valley of desolation. We knew that in the old days this was the main road from Chili into Argentina, and in places we saw tumbled-down shelter houses, now deserted, but of use in former times when travellers crossed the mountains by mule, for always they were provided with food and fuel. There was something wonderfully fascinating, crawling as it were to the roof of the world. It was easy to understand how superstitious Indians believed that evil spirits had their homes in the inaccessible fastnesses. There was no living thing to be seen anywhere except a couple of eagles. Gradually the panorama opened. We got a glimpse of the snow-covered heights in front of us. Then the brightness of the day disappeared; the sun was shrouded; there was a weird wail in the wind. A snowstorm came upon us. Still the engine, with something almost human in its determination, gripped the cogs and pulled us higher and higher yet. It was so cold we closed all windows and put on our coats, and called for the attendant to bring us beverages which we expected would produce warmth. Midday arrived before we reached Puerta del Inca, which was as far as we intended going. We had our car detached, and waved our hands to those on the express train, which soon disappeared amid the rushing snow. You may take it that the Incas never came to this part of the world. That they did is a piece of imagination. The so-called "Bridge of the Incas" is a natural formation. A little river has eaten its way through the hillside, and the tear and drip of water during untold centuries has formed a great natural arch. The water is volcanic and steamy, and has mineral qualities which stain the rocks with strange colourings. Of course, the benefits of the waters for rheumatism, and a score of other ailments, have been exploited. Galleries have been built under the arch, bath chambers cut above the rock, and water taken in pipes into each, so that visitors may have a "cure." In the summer time there are many visitors to Puerta del Inca to gain benefit not only from the waters, but from the mountain air, and to have a pleasant time by excursions into the hills. There is a commodious hotel.