The new Simplon tunnel, which was recently opened to traffic, is being operated with little difficulty from the natural rock heat that is encountered near the middle portion. At the same time, the ventilation has proved very satisfactory, in spite of the use of the ordinary coal-burning locomotives which are required, owing to the impossibity of operating with the new electric motive power, until the locomotives are specially insulated and equipped to withstand the moist vapors encountered. The temperature experienced in the cars range as high as 80° Fahr. near the middle of of the tunnel and correspondingly lower near the portals, but owing to perfect mechanical ventilation this does not prove objectionable, and the gases from the locomotives are said to be nowhere evident.

The entire trip from Domodossola, near the Italian portal, to Brig, on the Swiss side, requires but little over an hour, at ordinary operating speeds. The unfortunate feature of the tunnel condensation of moisture from the heated air near the middle on the cooler surfaces of the cars and equipment passing through this condition having rendered the electrical operation troublesome until it can be provided against by enclosure of the apparatus liable to be affected.