The new line starts from the coast at Arica and follows as straight a line to La Paz as the configuration of the country permits. The outstanding feature of this enterprise is the extreme altitude at which it lies for the greater part of its length, this ranging between 12,000 and 14,000 feet above the Pacific. Another fact is that the summit is not overcome by a tunnel, but the line passes right over the crests. The line measures 292 miles in length, and the sudden rise from the coast into the mountain country is effected by means of the toothed rail or rack system, the aggregate length of which is no less than 40 miles. Some idea of the conditions that confronted the railway-builders was afforded in the course of the surveys. In many places the engineers had to blast a trail out of the hard, solid rock with dynamite in order to advance. There are about 70 tunnels, though none are very long, for the most part piercing shoulders and spurs of the main range which could not be compassed or removed. At places very heavy bridging is essential, the spanning of one gorge in particular having presented a pretty problem. This ravine is 150 feet in width, and is crossed in a single span 150 feet above the raging river. Here, again, the extreme rarefaction of the atmosphere is a serious disadvantage against which the engineers have had to contend, while the fluctuations in temperature are extremely great. A difference of 113 degrees in the course of a day is by no means uncommon. At noon the thermometer will stand at 100, by nightfall it has dropped to 0.13 degrees. Such a rise and fall are tremendous, for at Greenwich, it may be pointed out, the same daily fluctuation averages about 17 degrees. Again, in the highest altitudes through which the line threads its way, water boils at 180 degrees, as compared with 212 degrees on the coast. In order to enable the workmen to prepare their food in such exposed, lofty situations, special vessels have had to be devised to prevent the water boiling over, for this result ensues long before the food is cooked properly, and the loss of water, even of only a pint, in such parched regions is a serious matter. In some places the country is as arid as the Sahara, and the water has had to be transported over great distances in barrels slung on the backs of mules. Large packs of these animals have been pressed into service for this work only. Similarly, the building material has had to be carried from the coast to the constructional camps strung out along the proposed route, by means of this ship of the Andes.