The Oroya and the Chimbote railways in South America demanded constant locations of this character. At many points it was necessary to suspend the persons making the preliminary measurements from the cliff above. The engineer who made these locations told the writer that on the Oroya line the galleries were often from 100 to 400 feet above the base of the cliff, and were generally reached from above. Rope ladders were used to great advantage. One 64 feet long and one 106 feet long covered the usual practice, and were sometimes spliced together. The side ropes were ¾ and 1¼ inches in diameter, and the rounds of wood 1¼ inches in diameter, and 16 inches and 24 inches long. These were notched at the ends and passed through the ropes, to which they were afterward lashed. These ladders could be rolled up and carried about on donkeys or mules. When swung over the side of a cliff and secured at the top, and when practicable at the bottom, they formed a very useful instrument in location and construction. For simple examination of the cliff, and for rough or broken slopes not exceeding 70 to 80 degrees, an active fellow would, after some experience, walk up and down such a slope simply grasping the rope in his hands. If required to do any work he would secure the rope about his body, or wind it around his arm, leaving his hands comparatively free for light work. The boatswain's chair--consisting of a wooden seat 6 inches wide and two feet long, through the ends of which pass the side ropes, looped at the top, and having their ends knotted--is a particularly convenient seat to use where cliffs overhang to a slight degree. The riggers were generally Portuguese sailors, who seemed to have more agility and less fear than any other men to be found. At Cuesta Blanca, on the Oroya, a prominent discoloration on the cliff served as a triangulation point for locating the chief gallery. Men were swung over the side of the cliff in a cage about 2½ feet by 6 feet, open at the top and on the side next the rock. This was a peculiar cliff about 1,000 feet high, rising from the river at a general slope of about 70 degrees. The grade line of the road was 420 feet above the river. The Chileno miners climbed up a rope ladder to a large seam near the grade, where they lived; provisions, water, etc., being hoisted up to them. The first men sent over the cliff to begin the preliminary work were lowered in a cage and took their dinners with them, for fear they would not return to the work, and that unless a genuine start was made others could not be induced to take their places. It is safe to say that 80 per cent. of the sixty odd tunnels on the Oroya and the seven tunnels on the Chimbote lines were located and constructed on lines determined by triangulation, and the results were so satisfactory that the method may be depended upon as the best system for determining topographical data or for locating and constructing the lines in any similar locality.