The relaying of most of the old Panama railroad was proceeding _pari passu_ with the construction of the canal. Two sections of the old line, one from Colon to Mindi at the Atlantic end, the other from Corozal to Panama at the Pacific end, could be used for the new. All the rest had to be built. The greater portion of the old track was, indeed, submerged beneath the waters of Lake Gatun. The line is also being doubled throughout almost its entire length. It was originally intended to carry the line through the Culebra Cut along a berm 10 feet above the water surface, to be left for this purpose during the excavations of the channel; but the "slides" interfered with this project, and a new line to the east of the Cut was selected. The heavy embankments along the railway were among the most useful and convenient "dumps" for the material taken out of the Culebra cutting. As a great part of the railroad passes through the lake, culverts of reinforced concrete are provided to equalize the water on both sides of the embankments. South of Miraflores the new railway passes through a tunnel 800 feet long, and a striking feature of the canal is a steel bridge across the Chagres River near Gamboa, almost a quarter of a mile long. We need not dwell on the excavations of the tidal stretches of the canal on the Atlantic and Pacific ends or through Lake Gatun. A good deal of the French work was available at the tidal levels, but a vast amount of excavation had still to be done by steam-shovels as well as dredges, rocky elevations being found in both channels. Below the Miraflores locks a million and a half cubic yards of rock had to be removed. There will be some tidal current at the Pacific end, but as the sea-level section here will be 500 feet wide, the current will never run faster than about one foot per second. The sea is practically tideless at the Atlantic terminal, the variation being only 2.5 as a maximum, whereas at the Pacific it is 21.1. CHAPTER XIV THE COMPLETED CANAL.