Yet it was not so much the engineering difficulties that this firm feared when they essayed the task, but the altitude at which it had to be accomplished. Again, there were difficulties incidental to transport, and the situations of the workings so far from any base. These were very great. It must be remembered that during the winter months--that is, from April to October--the tunnel workings and camps were cut off practically from the outside world. To plan one’s arrangements during the short summer so that when isolated there was no lack of material, food for the workmen, housing accommodation, as well as provision made for a thousand-and-one other details which were bound to arise, demanded considerable foresight, for work had to be maintained as steadily during the winter snows as under the summer sun. It is not every workman who will volunteer, or is physically capable, to brave the dangers attending the wielding of pick, shovel, wheelbarrow and explosives in the rarefied atmosphere and the adverse climatic conditions prevailing in winter among the highest altitudes of the Andes. The cold is intense, the snowfall is tremendous, and the winds rage with terrific fury. The frozen snow and ice are driven like sand in all directions, and with such force that they cut like a knife, and penetrate every crevice. Labour, indeed, proved a wearisome difficulty. Chilians figured most prominently among the workmen, and they proved to be very good labourers. There were a few Italians among them, with Englishmen occupying the controlling positions. At each end of the tunnel elaborate hospitals were erected replete with competent medical attention, for in addition to accidents there were the innumerable maladies provoked by the reduced atmospheric pressure which, unless skilfully tended in the incipient stages, are apt to develop very serious symptoms. Pneumonia was the chief cause of illness, attributable to insufficient clothing and care on the part of the Chilians. But after all is said and done, work at such an altitude is terribly exhausting under the most favourable conditions. On the Chilian side the constructional work was more imposing in character. It is only 46 miles from the Pacific portal of the tunnel to Los Andes, where junction is effected with the State railway systems. In this short distance there is a difference of some 8000 feet in levels, and the drop in the first 7 miles from the tunnel mouth is no less than 3,150 feet. The engineers were hard pushed to devise ways and means to lay the track so that it could be operated by the usual railway methods. Heavy grades, ranging from 6 to 8 per cent., could not be avoided to communicate each successive gallery carrying the metals along the mountain sides. The rack had to be resorted to freely, and the result is that the line describes a remarkable zigzag course, strikingly recalling the wonderful Stelvio road in the Tyrol.