The lift of the lower lock at Milaflores is variable, depending upon the level of the tidal water in the last reach of the Canal. The extreme range of the tide at La Boca, the Pacific entrance to the Canal, is 20 feet; that is to say, low water during "spring" tides is 10 feet below the average sea-level. During low tide on the Pacific side, therefore, the water in the Canal stands 95, instead of 85, feet above that sea. Hence the maximum lift of 32 feet already stated, for 32 × 3 = 96. [Illustration: MACHINE SHOPS, GORGONA.] [Illustration: CLUB HOUSE FOR EMPLOYEES, GORGONA.] Beyond the Milaflores locks our vessel enters a reach of the Canal which is exposed to the ebb and flow of the tide and _which will be confined within banks or levees as far as La Boca_. In this respect the plan and the section are both, unfortunately, misleading. The La Boca lock and dam have been abandoned, and no Sosa lake will therefore come into existence, the lowest lock being, as I have said, at Milaflores. I have thought it better to reproduce the existing maps as they stand rather than to attempt a re-draught which would necessarily be imperfect. Our vessel, then, below Milaflores is in a tidal channel and will be subject to some tidal current. By designing this channel so as to avoid a bottle neck, and by giving it a width of 500 feet, the calculated current will, however, not exceed 1 foot per second. The La Boca site for locks was found to be much too exposed to gun fire and other modes of attack from the sea, whereas the Milaflores site is not only distant about 5 miles from the shore, but is well sheltered both by hills near it and by the position of the hilly eminences of the shore line. It will be seen from the map that the dredged sea channel by which our vessel will reach deep water on the Pacific passes to the west of the Isle of Naos instead of to the east, as was proposed in the earlier plans. * * * * * Returning now to the Gatun locks. The mitre sill of the top lock is 37 feet above mean sea-level, _i.e._, 48 feet below the surface of the lake, which is 85 feet above mean sea-level. But the bottom of the lake here is only about 5 feet above sea-level, the total depth of water immediately above the locks and dam being 80 feet. It follows that, in the extreme case of both gates of one of the top locks (as well as the roller gate) being wrecked, the level of the water in the lake can only fall to the level of +37, which would leave a depth of 32 feet immediately above the dam. Ships of large draft could therefore lie there without being stranded. Moreover, the lake is so large that the outflow through the broken locks would only lower the level 2 feet _per diem_, so that more than three weeks would elapse before the water sank to the level of the mitre sill.