On the other plan, the Chagres and its tributaries would be made the feeders of the upper reaches of the canal. So far from being politely shown off the premises, the question rather was whether they would be able to supply sufficient water all the year round for the needs of the canal. Then this harnessing of the Chagres meant the taming of its waters in a huge artificial lake, in which the impetuous current would be quenched and through which the dredged channel of the waterway would run. The New Panama Company had recommended the construction of a huge dam for this purpose at Bohio towards the Atlantic end of the canal, and this plan had been adopted by the first American Isthmian Commission, which issued its report in 1901. I may add that the Spooner Act, which authorized the construction of a canal, also contemplated a lock or high-level waterway. As we shall see, Bohio was not in the end adopted as the site of the big dam, but Gatun, where it is now constructed, with its concrete spillway carrying away the overflow waters of the lake down the old Chagres channel to the near Atlantic. I need not say that these were two very different ways of "caring for" the Chagres and its affluents. The tide-level canal would also, of course, be supplied with sea-water, while the high-level will be a fresh-water canal. Colonel Goethals, the chief engineer of the canal, anticipates rather a curious result from this latter circumstance. He thinks the bed of the upper reaches of the canal will in course of time be quite paved with the barnacles washed by the fresh-water from the bottoms of the great ocean-going vessels passing through the canal. The second physical feature is the hill country or the "Continental Divide" which the canal enters near the point where the Chagres River crosses its course. Here runs the famous Culebra Cut, the nine-mile-long artificial canyon, the biggest excavation in the world. Now the highest elevation of these hills along the centre line of the canal was 312 feet above sea-level. The bottom of the canal at the cutting is 40 feet, so that the vertical depth of the cut on the centre line is 272 feet. The engineers of the tide-level scheme would have had not only to excavate 85 feet deeper--that is, to 45 feet below sea-level--but to make the cutting immensely wider in order to avoid the danger of disastrous landslides. This would have meant an enormous amount of additional work, as well as expense. Nevertheless, the controversy between the two principles was very warmly and equally sustained. It may be mentioned that Mr. Bunau-Varilla was an especially ardent advocate of the tide-level scheme. In fact, he was not for calling the waterway a canal at all; he would have christened it "the Straits of Panama."