Of the deviations, or rather the prolongations or extensions of the railway, to avoid sharp turns or zig-zags, there are four between Lanslebourg and the summit. At all these zig-zags, as we know in our experience of turns in hilly or mountain roads, the gradient is always steeper than at other parts; but the deviations of the Cenis, by taking sweeps carried through eight little tunnels in the mountain, the longest of which is 105 metres, the shortest 40, and by increasing the actual distance three to four times what it is by the roadway, curves of larger radius and lighter gradient are obtained. The total length of these tunnels is 505 metres. On the Italian side there are ten deviations, and they would have been nearly double that number, had not the railway, instead of following the existing road at a part called _les Echelles_, about five miles from the summit, reverted to the old road which had been abandoned in consequence of the prevalence of avalanches along it in winter. Whilst the new road is undoubtedly superior for carriages to the old one, the latter is better suited for a railway, in consequence of their being no zig-zags upon it; but _en revanche_ for this advantage, it has been necessary to cover the line over. 600 metres of this covering are massive and solid masonry, upon which avalanches will impinge, as they are hurled from the rocks above into the abyss beneath. In addition, there will be, hereabouts, 1,200 metres of covered way, of which we shall speak immediately. There are several other places on the Italian side of the mountain at which protection against avalanches must be afforded by means of similar galleries. Their total length will be 1,480 metres, or about 140 yards less than a mile, and with this amount all the Engineers seem to agree (notwithstanding the assertion of Mr. Crawford, M.P., to the contrary) that the railway will be completely protected from the avalanche danger. But snow is the cause of inconvenience as well as of danger. If snow would be satisfied to remain quietly when it falls on _terra firma_, the snow-plough on the engines and the shovels of a few permanent-way men would speedily send it off the line without trouble or delay; but snow is invariably accompanied, especially in these elevated regions, with high winds, and these cause drifts. There is an almost undeviating rule as regards drifts, and it is that a drift of this year will find its way to, practically, the same spot that it was at last year, the previous year, and the year previous to that also, and it will be at the same spot next year, the following year, and so on _ad infinitum_. Hence it is necessary, on the Mont Cenis, to protect the railway by means of covered ways, in addition to protecting them from avalanches by galleries. The covered ways are constructed, combinedly, of wood and of timber. They require to be sufficiently strong to resist the effects of high winds or _tourmentes_, and the