CHAPTER XVII

THE CONQUEST OF THE ISTHMUS

THE Isthmus of Panama * runs nearly east and west, and the canal traverses it from Colon on the north to Panama on the south, in a general direction from northwest to southeast, the Pacific terminus being twenty-two miles east of the Atlantic entrance.

The greatest difficulty of the canal project now nearing completion was and is the control and disposal of the waters of the Chagres River, and its many tributaries. The Chagres runs a circuitous serpentine course, backwards and forwards across the Isthmus from its source in the San Blas Mountains, emptying into the Caribbean Sea a mile or two west of Limon Bay. One of the merits claimed for the canal plan as finally adopted is that it converts what was an obstacle into the motive power of the colossal project, for without the formerly greatly feared floods of the Chagres the canal would simply be a dry ditch, useless for navigation.

The American canal consists of a sea-level entrance channel from Limon Bay to Gatun, about seven miles long, forty-one feet deep at mean tide, and with a bottom width of five hundred feet. At Gatun the canal becomes a high-level canal, from which it takes its name. Here a mammoth dam has been constructed across the valley by which the waters of the Chagres

*For text of treaty with the Republic of Panama and commercial statistics, see Appendix J, page 460.

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River are impounded and a lake, which will have an area of about a hundred and sixty-four square miles, is formed. This high level is maintained until Pedro Miguel, thirty-two miles away, is reached. Here the Pacific side of the lake is confined by a dam between the hills, and here also the descent towards a lower level begins through the locks.

The Gatun dam, which is the bulwark of the reservoir lake, is nearly one mile and a half long, measured on its crest, fully half a mile wide at its base, and about four hundred feet wide at the water surface, and the crest, as planned, will be at an elevation of one hundred and fifteen feet above mean sea-level and about thirty feet above the expected normal level of the lake. Of the total length of the dam only five hundred feet, or one-fifteenth part, will be exposed to the maximum water head or pressure of eighty-five feet. As a matter of fact this bulwark is a mountain rather than a dam, and it is confidently expected that a view of its colossal proportions will disarm those critics of the project who have ever thought to see in an earthen dam at this point the fatal weakness of the high-level plan.

The spillway in the dam is a concrete-lined opening twelve hundred feet long and three hundred feet wide cut through a hill of rock nearly in the centre of the dam, the bottom of the spillway opening being ten feet above sea-level. There are six double locks of concrete in the canal, three pairs in flight at Gatun, with a combined lift or drop of eighty-five feet. One pair at Pedro Miguel with a lift or drop of thirty and a third feet, and two pairs at Miraflores with a combined lift or drop of fifty-four feet eight inches at

mean tide. For sixteen miles from the Gatun dam the canal channel will be a thousand feet broad, then for four miles it will narrow to eight hundred feet and for four miles further, indeed to the northern entrance of Culebra cut at Bas Obispo, it will have a width of five hundred feet, with depth varying from eighty-five feet to forty-five feet the minimum. The water level in the cut will, of course, be that of the lake and with a miniumum depth of forty-five feet. Through the cut the minimum bottom width of the canal, three hundred feet, will be reached.

On the Pacific side of the cut or continental divide the canal work consists, in addition to the locks already enumerated, of the breakwaters extending from Balboa to Naos Island, a distance of a little more than three miles, and the excavation of the canal and ocean channel to deep water in the Pacific. At the Pacific entrance of the canal the fluctuations of tide are considerable, amounting to nearly twenty feet. The arrangements in the form of gates in the tidal lock, by which this obstacle is to be met, are new and untried, and there is no absolute certainty that they will work successfully. Here we are face to face with one of several important details of the great construction which are absolutely without precedent, and whose strength or weakness will only be apparent when the canal is completed.

The length of the canal from shore-line to shoreline is about forty miles. From deep water to deep water it is ten miles longer. Throughout its course there are no lazy turns, a thing which the mariner notes with delight. The changing course is met by a succession of twenty-two clean-cut angles, without excessive

curvature in any place such as would retard or endanger navigation.

Even from the above fragmentary sketch of the canal project the vital importance of an adequate water supply will be apparent. Critics of the highlevel plan, which we adopted, have not of late so frequently repeated their criticisms of the Gatun dam, but on the question of whether we have enough water to work the canal they are far from being silent. And, of course, in a sense their criticism is not without foundation-however magnificent the dam, however wonderful the locks, and however accurate the electrical appliances to supply the power, sea-going ships will not be able to pass from ocean to ocean, and the dream of centuries will not be realised, unless the water-level of forty-five feet is always maintained in the channel of the interoceanic waterway.

The confidence of the canal engineers in the adequacy of the visible water supply to maintain the necessary water-level is based on figures, measurements, and observations which were started by the French in 1880, and have been continued by ourselves. What appear to be liberal allowances are made for evaporation and seepage and leakage at the water gates of the locks. However, should these figures prove to be deceptive, should in the dry season water not be forthcoming in sufficient quantities for all the lockages desired, the canal will not remain on our hands as the hopeless wreck of a colossal blunder, as these critics maintain will be the case. To meet this contingency, which it is hoped, and with much show of reason, will never arise, a suitable site has been chosen up the Chagres River, ten miles away from

the canal prism, where in the season of floods and rains great quantities of water could be accumulated, to be drawn upon in the dry season, in case of shortage. The site of this emergency or secondary dam has been selected and the plan fully worked out, but construction work has not begun, and I understand will not be, until the necessity for the same becomes more apparent.

The great work as outlined above is presided over by Colonel Goethals the master-builder, seconded by Colonel Hodges, assistant chief engineer and designer of the permanent structure of the canal. It is subdivided into three main sections, Colonel Sibert of the Engineers being in charge of the Atlantic Division, while Colonel Gaillard, also of the Army, is in charge of the central division, which includes the Gatun lake and the Culebra cut. The Pacific Division is the peculiar domain of Mr. S. B. Williamson, a civil engineer of great distinction, one of the many such who are numbered among the alumni of the Virginia Military Institute. Admiral Rousseau is the worthy representative of the Navy in the great work, while the duties of Mr. Joseph B. Bishop, the secretary of the Commission, are many and exacting, as are those in a different sphere of Mr. Thatcher, the civil administrator of the Canal Zone.

The first days of the visitor (if he is a layman) in the Canal Zone, as a rule, leave only a confused recollection of many things seen and little understood. Generally he rushes wildly about for a week of bewildered days, dividing his time with strict impartiality between the many great and striking features of the work. Then, if he is wise, he settles down and tries