The Panama Canal

The journey of the U. S. S. Oregon around the Horn from Pacific waters to the theater of the War with Spain in the Caribbean, in 1898, impressed upon the American public the necessity of building the canal as a measure of national defense. Commercial interests long had been convinced of its necessity as a factor in both national and international trade, and, when it was realized that the Oregon would have saved 8,000 miles if there had been a canal at Panama, the American mind was made up. It determined that the canal should be built, whatever the cost.

From the very first there was never any question that the necessary money would be forthcoming. It is a fact unprecedented in all parliamentary history that all of the appropriations necessary for the construction and completion of the Isthmian waterway were made by Congress without a word of serious protest.

During the same War with Spain that convinced the United States that the canal must be built, a long forward step was taken in the science of medicine as concerned with the prevention and control of tropical diseases. The theory that yellow fever was transmitted by mosquitoes had been proved by a Cuban physician, Dr. Carlos Finley, a score of years earlier. An Englishman, Sir Patrick Manson, had first shown that disease might be transmitted by the bites of insects, and another Englishman, Maj. Roland Ross, had shown that malaria was conveyed by mosquitoes. It remained, however, for American army surgeons to demonstrate, as they did in Cuba, that yellow fever was transmissible only by mosquitoes of the stegomyia variety and by no other means whatsoever.

With this knowledge in their possession the Americans were able to do what the French were not—to control the chief enemy of mankind in torrid climes. In the first years of the work the public, and Congress, reflecting its views, were not sufficiently convinced of the efficacy of the new scientific discoveries to afford the means for putting them into effect. The Isthmian Canal Commission refused to honor requisitions for wire screens, believing that they were demanded to add to the comfort and luxury of quarters on the Zone, rather than for protection against disease. But the outbreak of yellow fever in 1905 was the occasion for furnishing the Sanitary Department, under Col. W. C. Gorgas, with the necessary funds, and thus provided, he speedily and completely stamped out the epidemic. From that time on, no one questioned the part that sanitation played in the success of the project. The cities of Panama and Colon were cleaned up as never were tropical cities cleaned before. All the time, every day, men fought mosquitoes that the workers in the ditch might not be struck down at their labors.

The Americans, too, made mistakes. In the beginning they attempted to build the canal under the direction of a commission with headquarters in Washington. This commission, at long distance and by methods hopelessly involved in red tape, sought to direct the activities of the engineer in charge on the Isthmus. The public also was impatient with the long time required for preparation and insistently demanded that "the dirt begin to fly."

The work was begun in 1904. It proceeded so slowly that two years later the chairman of the Isthmian Canal Commission asserted that it must be let out to a private contractor, this being, in his opinion, the only way possible to escape the toils of governmental red tape. The then chief engineer, the second man who had held that position while fretting under these methods, was opposed to the contract system. Bids were asked for, however, but all of them were rejected.

Fortunately, Congress from the beginning had left the President a practically free hand in directing the course of the project. Mr. Roosevelt reorganized the commission, made Col. George W. Goethals, an Army engineer, chairman of the commission and chief engineer of the canal. The constitution of the commission was so changed as to leave all the power in the hands of the chairman and to lay all of the responsibility upon his shoulders.

It was a master stroke of policy, and the event proved the choice of the man to be admirable in every way. From the day the Army engineers took charge there was never any more delay, never any halt in progress, and the only difficulties encountered were those of resistant Nature (such as the slides in Culebra Cut) and those of misinformed public opinion (such as the absurd criticism of the Gatun Dam).

The Americans, too, in the early stages of the work were hampered by reason of the fact that the final decision as to whether to build a sea-level canal or a lock canal was so long delayed by the conflicting views of the partisans of each type in Congress, in the executive branches of the Government, and among the engineers. This problem, too, was solved by Mr. Roosevelt. He boldly set aside the opinion of the majority of the engineers who had been called in consultation on the problem, and directed the construction of a lock canal. The wisdom of this decision has been so overwhelmingly demonstrated that the controversy that once raged so furiously now seems to have been but a tiny tempest in an insignificant teapot.

One other feature of the course of events under the American régime at Panama must be considered. Graft and corruption had ruined the French; the Americans were determined that whether they succeeded or not, there should be no scandal. This, indeed, in part explains why there was so much apparently useless circumlocution in the early stages of the project. Congress, the President, the engineers, all who were in responsible position, were determined that there should be no graft. There was none.

Not only were the Americans determined that the money voted for the canal should be honestly and economically expended, but they were determined, also, that the workers on the canal should be well paid and well cared for. To this end they paid not only higher wages than were current at home for the same work, but they effectively shielded the workers from the exactions and extortions of Latin and Oriental merchants by establishing a commissary through which the employees were furnished wholesome food at reasonable prices—prices lower, indeed, than those prevailing at home.

As a result of these things the spirit of the Americans on the Canal Zone, from the chairman and chief engineer down to the actual diggers, was that of a determination to lay the barrier low, and to complete the job well within the limit of time and at the lowest possible cost. In this spirit all Americans should rejoice, for it is the highest expression of the nearest approach we have made to the ideals upon which the Fathers founded our Republic.

It is impossible to leave out of the reckoning, in telling the story of the canal, the checkered history of the diplomatic engagements on the part of the United States, that have served both to help and to hinder the undertaking. What is now the Republic of Panama has been, for the greater part of the time since continental Latin America threw off the yoke of Spain, a part of that Republic having its capital at Bogota, now under the name of Colombia, sometimes under the name of New Granada, sometimes a part of a federation including Venezuela and Ecuador. The United States, by virtue of the Monroe doctrine, always asserted a vague and undefined interest in the local affairs of the Isthmus. This was translated into a concrete interest when, in 1846, a treaty was made, covering the construction of the railroad across the Isthmus, the United States engaging always to keep the transit free and open. Great Britain, by virtue of small territorial holdings in Central America and of larger claims there, also had a concrete interest, which was acknowledged by the United States, in the Clayton-Bulwer treaty of 1850, under which a projected canal should be neutral under the guarantee of the Governments of the United States and Great Britain.

For years the United States was inclined to favor a canal cut through Nicaragua, rather than one at Panama, and, after 1898, when the American nation had made up its mind to build a canal somewhere, the partisans of the Panama and Nicaragua routes waged a bitter controversy.

Congress finally decided the issue by giving the President authority to construct a canal at Panama, with the proviso that should he be unable to negotiate a satisfactory treaty with Colombia, which then owned the Isthmus, he should proceed to construct the canal through Nicaragua. Under this threat of having the scepter of commercial power depart forever from Panama, Colombia negotiated a treaty, known as the Hay-Herran treaty, giving the United States the right to construct the canal. This treaty, however, failed of ratification by the Colombian Congress, with the connivance of the very Colombian President who had negotiated it.

But President Roosevelt was most unwilling to accept the alternative given him by Congress—that of undertaking the canal at Nicaragua—and this unwillingness, to say the least, encouraged a revolution in Panama. This revolution separated the Isthmus from the Republic of Colombia, and set up the new Republic of Panama. As a matter of fact, Panama had had but the slenderest relations with the Bogota Government, had been for years in the past an independent State, had never ceased to assert its own sovereignty, and had been, indeed, the theater of innumerable revolutions.

The part the United States played in encouraging this revolution, the fact that the United States authorities prevented the transit of Colombian troops over the Panama Railway, and that American marines were landed at the time, has led to no end of hostile criticism, not to speak of the still pending and unsettled claims made by Colombia against the United States. Mr. Roosevelt himself, years after the event and in a moment of frankness, declared: "I took Panama, and left Congress to debate it later."

Whatever may be the final outcome of our controversy with Colombia, it may be confidently predicted that history will justify the coup d'état on the theory that Panama was the best possible site for the interoceanic canal, and that the rupture of relations between the territory of the Isthmus and the Colombian Republic was the best possible solution of a confused and tangled problem.

These diplomatic entanglements, however, as the canal is completed, leave two international disputes unsettled—the one with Colombia about the genesis of the canal undertaking, and the other with Great Britain about the terms of its operation.

Congress, in its wisdom, saw fit to exempt American vessels engaged exclusively in coastwise trade—that is to say, in trade solely between ports of the United States—from payment of tolls in transit through the canal. This exemption was protested by Great Britain on the ground that the Hay-Pauncefote treaty, which took the place of the Clayton-Bulwer treaty, provided that the canal should be open to all nations on exact and equal terms. The future holds the termination of both these disputes.

Congress, that never begrudged an appropriation, indulged in many disputes concerning the building and operation of the canal. First, there was the controversy as to site, between Nicaragua and Panama. Next, came the question as to whether the canal should be at sea level or of a lock type. Then there was the question of tolls, and the exemption of American coastwise traffic. But, perhaps the most acrimonious debates were on the question as to whether or not the canal should be fortified. Those who favored fortification won their victory, and the canal was made, from a military standpoint, a very Gibraltar for the American defense of, and control over, the Caribbean. That this was inevitable was assured by two facts: One that the trip of the Oregon in 1898 crystallized public sentiment in favor of constructing the canal; and the other that the canal itself was wrought by Army engineers under the direction of Colonel Goethals. Colonel Goethals never for a moment considered the possibility that Congress would vote against fortifications, and the whole undertaking was carried forward on that basis.

If the military idea, the notion of its necessity as a feature of the national defense, was the determining factor in initiating the canal project, it remains a fact that its chief use will be commercial, and that its money return, whether small or large, nearly all will be derived from tolls assessed upon merchant vessels passing through it.

The question of the probable traffic the canal will be called upon to handle was studied as perhaps no other world-wide problem of transportation ever was. Prof. Emory R. Johnson was the student of this phase of the question from the beginning to the end. He estimates that the canal in the first few years of its operation will have a traffic of 10,000,000 tons of shipping each year, and that by 1975 this will have increased to 80,000,000 tons, the full capacity of the canal in its present form. Provision has been made against this contingency by the engineers who have so constructed the canal that a third set of locks at each end may be constructed at a cost of about $25,000,000, and these will be sufficient almost to double the present ultimate capacity, and to take care of a larger volume of traffic than now can be foreseen.

Americans are interested, first of all, in what the canal will do for their own domestic trade. It brings Seattle 7,800 miles nearer to New York; San Francisco, 8,800 miles nearer to New Orleans; Honolulu 6,600 miles nearer to New York than by the Strait of Magellan. Such saving in distance for water-borne freight works a great economy, and inevitably must have a tremendous effect upon transcontinental American commerce.

In foreign commerce, also, some of the distances saved are tremendous. For instance, Guayaquil, in Ecuador, is 7,400 miles nearer to New York by the canal than by the Strait of Magellan; Yokohama is nearly 4,000 miles nearer to New York by Panama than by Suez; and Melbourne is 1,300 miles closer to Liverpool by Panama than by either Suez or the Cape of Good Hope. Curiously enough, the distance from Manila to New York, by way of Suez and Panama, is almost the same, the difference in favor of Panama being only 41 miles out of a total of 11,548 miles. The difference in distance from Hongkong to New York by the two canals is even less, being only 18 miles, this slight advantage favoring Suez.

But it is not by measure of distances that the effect of the canal on international commerce may be measured. It spells the development of the all but untouched western coast of South America and Mexico. It means a tremendous up-building of foreign commerce in our own Mississippi Valley and Gulf States. It means an unprecedented commercial and industrial awakening in the States of our Pacific coast and the Provinces of Western Canada.

While it was not projected as a money-making proposition, it will pay for its maintenance and a slight return upon the money invested from the beginning, and in a score of years will be not only self-supporting, but will yield a sufficient income to provide for the amortization of its capital in a hundred years.

The story of how this titanic work was undertaken, of how it progressed, and of how it was crowned with success, is a story without a parallel in the annals of man. The canal itself, as Ambassador Bryce has said, is the greatest liberty man has ever taken with nature.

Its digging was a steady and progressive victory over sullen and resistant nature. The ditch through Culebra Mountain was eaten out by huge steam shovels of such mechanical perfection that they seemed almost to be alive, almost to know what they were doing. The rocks and earth they bit out of the mountain side were carried away by trains operating in a system of such skill that it is the admiration of all the transportation world, for the problem of disposing of the excavated material was even greater than that of taking it out.

The control of the torrential Chagres River by the Gatun Dam, changing the river from the chief menace of the canal to its essential and salient feature, was no less an undertaking. And, long after Gatun Dam and Culebra Cut cease to be marvels, long after the Panama Canal becomes as much a matter of course as the Suez Canal, men still will be thrilled and impressed by the wonderful machinery of the locks—those great water stairways, operated by machinery as ingenious as gigantic, and holding in check with their mighty gates such floods as never elsewhere have been impounded.

It is a wonderful story that this book is undertaking to tell. There will be much in it of engineering feats and accomplishments, because its subject is the greatest of all engineering accomplishments. There will be much in it of the things that were done at Panama during the period of construction, for never were such things done before. There will be much in it of the history of how and why the American Government came to undertake the work, for nothing is of greater importance. There will be something in it of the future, looking with conservatism and care as far ahead as may be, to outline what the completion of this canal will mean not only for the people of the United States, but for the people of all the world.

Much that might be written of the romantic history of the Isthmian territory—tales of discoverers and conquistadores, wild tales of pirates and buccaneers, serio-comic narratives of intrigue and revolution—is left out of this book, because, while it is interesting, it now belongs to that antiquity which boasts of many, many books; and this volume is to tell not of Panama, but of the Panama Canal—on the threshold of its story, fitted by a noble birth for a noble destiny.

CHAPTER II

We are told that the excavations total 232,000,000 cubic yards; that the Gatun Dam contains 21,000,000 cubic yards of material; and that the locks and spillways required the laying of some 4,500,000 cubic yards of concrete. But if one is to realize the meaning of this he must get out of the realm of cubic yards and into the region of concrete comparisons. Every one is familiar with the size and shape of the Washington Monument. With its base of 55 feet square and its height of 555 feet, it is one of the most imposing of all the hand reared structures of the earth. Yet the material excavated from the big waterway at Panama represents 5,840 such solid-built shafts. Placed in a row with base touching base they would traverse the entire Isthmus and reach 10 miles beyond deep water in the two oceans at Panama. Placed in a square with base touching base they would cover an area of 475 acres. If all the material were placed in one solid shaft with a base as large as the average city block, it would tower nearly 100,000 feet in the air.

Another illustration of the magnitude of the quantity of material excavated at Panama may be had from a comparison with the pyramid of Cheops, of which noble pile some one has said that "All things fear Time, but Time fears only Cheops." We are told that it required a hundred thousand men 10 years to make ready for the building of that great structure, and 20 years more to build it. There were times at Panama when, in 26 working days, more material was removed from the canal than was required to build Cheops, and from first to last the Americans removed material enough to build sixty-odd pyramids such as Cheops. Were it all placed in one such structure, with a base as large as that of Cheops, the apex would tower higher into the sky than the loftiest mountain on the face of the earth.

Still another way of arriving at a true conception of the work of digging the big waterway is to consider that enough material had to be removed by the Americans to make a tunnel through the earth at the equator more than 12 feet square.

Yet all these comparisons have taken account of the excavations only. The construction of the Panama Canal represents much besides digging a ditch, for there were some immense structures to erect. Principal among these, so far as magnitude is concerned, was the Gatun Dam, that big ridge of earth a mile and a half long, half a mile thick at the base, and 105 feet high. It contains some 21,000,000 cubic yards of material, enough to build more than 500 solid shafts like the Washington Monument. Then there was the dam at Pedro Miguel—"Peter Magill," as the irreverent boys of Panama christened it—and another at Miraflores, each of them small in comparison with the great embankment at Gatun, but together containing as much material as 70 solid shafts like our Washington Monument.

Besides these structures there still remain the locks and spillways, with their four and a half million cubic yards of concrete and their hundreds and thousands of tons of steel.

With all these astonishing comparisons in mind, is it strange that the digging of the Panama Canal is the world's greatest engineering project? Are they not enough to stamp it as the greatest single achievement in human history? Yet even they, pregnant of meaning as they are, fail to reveal the full and true proportions of the work of our illustrious army of canal diggers. They tell nothing of the difficulties which were overcome—difficulties before which the bravest spirit might have quailed.

When the engineers laid out the present project, they calculated that 103,000,000 cubic yards of material would have to be excavated, and predicted that the canal diggers would remove that much in nine years. Since that time the amount of material to be taken out has increased from one cause or another until it now stands at more than double the original estimate. At one time there was an increase for widening the Culebra Cut by 50 per cent. At another time there was an increase to take care of the 225 acres of slides that were pouring into the big ditch like glaciers. At still another time there was an increase for the creation of a small lake between the locks at Pedro Miguel and Miraflores. At yet another time it was found that the Chagres River and the currents of the Atlantic and the Pacific Oceans were depositing large quantities of silt and mud in the canal, and this again raised the total amount of material to be excavated. But none of these unforeseen obstacles and additional burdens dismayed the engineers. They simply attacked their problem with renewed zeal and quickened energy, with the result that they excavated in seven years of actual operations more than twice as much material as they were expected to excavate in nine years. In other words, the material to be removed was increased 125 per cent and yet the canal was opened at least 12 months ahead of the time predicted.

How this unprecedented efficiency was developed forms in itself a remarkable story of achievement. The engineers met with insistent demands that they "make the dirt fly." The people had seen many months of preparation, but they had no patience with that; they wanted to see the ditch begin to deepen. It was a critical stage in the history of the project. If the dirt should fail to fly public sentiment would turn away from the canal.

So John F. Stevens addressed himself to making it fly. Before he left he had brought the monthly output almost up to the million yard mark. When that mark was passed the President of the United States, on behalf of himself and the nation, sent a congratulatory message to the canal army. Many people asserted that it was nothing but a burst of speed; but the canal diggers squared themselves for a still higher record. They forced up the mark to two million a month, and straightway used that as a rallying point from which to charge the heights three million. Once again the standard was raised; "four million" became the slogan. Wherever that slogan was flashed upon a Y.M.C.A. stereoptican screen there was cheering—cheering that expressed a determined purpose. Finally, when March, 1909, came around all hands went to work with set jaws, and for the only time in the history of the world, there was excavated on a single project, 4,000,000 cubic yards of material in one month.

With the dirt moving, came the question of the cost of making it fly. By eliminating a bit of lost motion here and taking up a bit of waste there, even with the price of skilled labor fully 50 per cent higher on the Isthmus than in the States, unit costs were sent down to surprisingly low levels. For instance, in 1908 it was costing 11¹⁄₂ cents a cubic yard to operate a steam shovel; in 1911 this had been forced down to 8⁷⁄₈ cents a yard. In 1908 more than 18¹⁄₂ cents were expended to haul a cubic yard of spoil 8 miles; in 1911 a cubic yard was hauled 12 miles for a little more than 15¹⁄₅ cents.

Some of the efficiency results were astonishing. To illustrate: One would think that the working power of a ton of dynamite would be as great at one time as another; and yet the average ton of dynamite in 1911 did just twice as much work as in 1908. No less than $50,000 a month was saved by shaking out cement bags.

It was this wonderful efficiency that enabled the United States to build the canal for $375,000,000 when without it the cost might have reached $600,000,000. In 1908, after the army had been going at regulation double-quick for a year, a board was appointed to estimate just how much material would have to be taken out, and how much it would cost. That board estimated that the project as then planned would require the excavation of 135,000,000 cubic yards of material, and that the total cost of the canal as then contemplated would be $375,000,000. Also it was estimated that the canal would be completed by January 1, 1915. After that time the amount of material to be excavated was increased by 97,000,000 cubic yards, and yet so great was the efficiency developed that the savings effected permitted that great excess of material to be removed without the additional expense of a single penny above the estimates of 1908, and in less time than was forecast.

Although the difficulties that beset the canal diggers were such as engineers never before encountered, they were met and brushed aside, and all the world's engineering records were smashed into smithereens. It required 20 years to build the Suez Canal, through a comparatively dry and sandy region. When the work at Panama was at its height the United States was excavating the equivalent of a Suez Canal every 15 months. Likewise it required many years to complete the Manchester Ship Canal between Liverpool and Manchester, a distance of 35 miles. This canal cost so much more than was estimated that money was raised for its completion only with the greatest difficulty. Yet at Panama the Americans dug four duplicates of the Manchester Ship Canal in five years. All of this was done in spite of the fact that they had to work in a moist, hot, enervating climate where for nine months in a year the air seems filled with moisture to the point of saturation, and where, for more than half the length of the great ditch, the annual rainfall often amounts to as much as 10 feet—all of this falling in the nine months of the wet season.

A few comparisons outside of the construction itself will serve to illustrate the tremendous proportions of the work. Paper money was not handled at all in paying off the canal army. It took three days to pay off the force with American gold and Panaman silver. When pay day was over there had been given into the hands of the Americans, and thrown into the hats of the Spaniards and West Indian negroes, 1,600 pounds of gold and 24 tons of silver. When it is remembered that this performance was repeated every month for seven years, one may imagine the enormous outlay of money for labor.

The commissary also illustrates the magnitude of the work. Five million loaves of bread, a hundred thousand pounds of cheese, more than 9,000,000 pounds of meat, half a million pounds of poultry, more than a thousand carloads of ice, more than a million pounds of onions, half a million pounds of butter—these are some of the items handled in a single year.

Wherever one turns he finds things which furnish collateral evidence of the magnitude of the work. The Sanitary Department used each year 150,000 gallons of mosquito oil, distributed thousands of pounds of quinine, cut and burned millions of square yards of brush, and spent half a million dollars for hospital maintenance.

No other great engineering project has allowed such a remarkable "margin of safety"—the engineering term for doing things better than they need to be done. The engineers who dug the canal took nothing for granted. No rule of physics was so plain or so obvious as to escape actual physical proof before its acceptance, when such proof was possible. No one who knows how the engineers approached the subject, how they resolved every doubt on the side of safety, and how they kept so far away from the danger line as actually to make their precaution seem excessive can doubt that the Panama Canal will go down in history as the most thorough as well as the most extensive piece of engineering in the world.

CHAPTER III

Around no other structure in the history of engineering did the fires of controversy rage so furiously and so persistently as they raged for several years around Gatun Dam. It was attacked on this side and that; its foundations were pronounced bad and its superstructure not watertight. Doubt as to the stability of such a structure led some of the members of the Board of Consulting Engineers to recommend a sea-level canal. Further examination of the site and experimentation with the materials of which it was proposed to construct it, showed the engineers that it was safe as to site and satisfactory as to superstructure. The country had about accepted their conclusions, when, in the fall of 1908, there was a very heavy rain on the Isthmus, and some stone which had been deposited on the soil on the upstream toe of the dam, sank out of sight—just as the engineers expected it to do. A story thereupon was sent to the States announcing that the Gatun Dam had given way and that the Chagres River was rushing unrestrained through it to the sea. The public never stopped to recall that the dam was not yet there to give way, or to inquire exactly what had happened, and a wave of public distrust swept over the country.

To make absolutely certain that everything was all right, and to restore the confidence of the people in the big project, President Roosevelt selected the best board of engineers he could find and sent them to the Isthmus in company with President-elect Taft to see exactly what was the situation at Gatun.

They examined the site, they examined the material, they examined the evidence in Colonel Goethal's hands. When they got through they announced that they had only one serious criticism to make of the dam as proposed. "It is not necessary to tie a horse with a log chain to make sure he can not break away," observed one of them, "a smaller chain would serve just as well." And so they recommended that the crest of the dam be lowered from 135 feet to 115 feet. Still later this was cut to 105 feet. They found that the underground river whose existence was urged by all who opposed a lock canal, flowed nowhere save in the fertile valleys of imagination. The engineers had known this a long time, but out of deference to the doubters they had decided to drive a lot of interlocking sheet piling across the Chagres Valley. "What's the use trying to stop a river that does not exist?" queried the engineers, and so the sheet piling was omitted.

As a matter of fact, Gatun Dam proved the happiest surprise of the whole waterway. In every particular it more than fulfilled the most optimistic prophecies of the engineers. They said that what little seepage there would be would not hurt anything; the dam answered by showing no seepage at all. They said that the hydraulic core would be practically impervious; it proved absolutely so. Where it was once believed that Gatun Dam would be the hardest task on the Isthmus it proved to be the easiest. Culebra Cut exchanged places with it in that regard.

Gatun Dam contains nearly 22,000,000 cubic yards of material. Assuming that it takes two horses to pull a cubic yard of material it would require twice as many horses as there are in the United States to move the dam were it put on wheels. Loaded into ordinary two-horse dirt wagons it would make a procession of them some 80,000 miles long. The dam is a mile and a half long, a half mile thick at the base, 300 feet thick at the water line, and 100 feet thick at the crest. Its height is 105 feet.

Yet in spite of its vast dimensions it is the most inconspicuous object in the landscape. Grown over with dense tropical vegetation it looks little more conspicuous than a gradual rise in the surface of the earth. Passengers passing Gatun on the Panama Railroad scarcely recognize the dam as such when they see it, so gradual are its slopes. An excellent idea of the gentle incline of the dam may be had by referring to the accompanying figure, which shows the outlines of a cross section of the dam.

The materials of which it is constructed are also shown there. Starting on the upstream side there is a section made of solid material from Culebra Cut. Beyond this is the upstream toe of the dam, which is made of the best rock in the Culebra Cut. After this comes the hydraulic fill. This material is a mixture of sand and clay which, when it dries out thoroughly, is compact and absolutely impervious to water. It was secured from the river channel and pumped with great 20-inch centrifugal pumps into the central portion of the dam, where a veritable pond was formed; the heavier materials settled to the bottom, forming layer after layer of the core, while the lighter particles, together with the water, passed off through drain pipes. In this way the water was not only the hod carrier of the dam construction, but the stone mason as well. Where there was the tiniest open space, even between two grains of sand, the water found it and slipped in as many small particles as were necessary to stop it up.

The Chagres Valley is a wide one until it reaches Gatun. Here it narrows down to a mile and a half. It is across this valley that the Gatun Dam is thrown in opposition to the seaward journey of the Chagres waters. At the halfway point across the valley there was a little hill almost entirely of solid rock. It happened to be planted exactly at the place the engineers needed it. Here they could erect their spillway for the control of the water in the lake above.

In controlling the Chagres, the engineers again took what on any private work would have been regarded as absurd precaution. In the first place, Gatun Lake will be so big that the Chagres can break every record it heretofore has set, both for momentary high water and for sustained high water, and still, with no water being let out of the lake, it can continue to flow that way for a day and a half without disturbing things at all. It could flow for two days before any serious damage could be done. Thus the canal force might be off duty for some 45 hours, with the outlet closed, before any really serious damage could be done by the rampage of the river.

But of course no one supposes that it would be humanly possible that two such contingencies as the highest water ever known, and everybody asleep at their posts for two days, could happen together. When the water in the lake reached its normal level of 87 feet the spillway gates would be opened, and, if necessary, it would begin to discharge 145,000 feet of water a second. This is 17,000 feet more than the record for sustained flow heretofore set by the Chagres. But if it were found that even this was inadequate the culverts in the locks could be brought into play, and with them the full discharge would be brought up to 194,000 feet a second, or 57,000 more than the Chagres has ever brought down. But suppose even this would not suffice to take care of the floods of the Chagres? The spillway is so arranged that as the level of the water in the lake rises the discharging capacity increases. With the spillway open, even if the Chagres were to double its record for continued high water, it would take many days to bring the lake level up to the danger point—92 feet. When it reached that height the spillway would have a capacity of 222,000 feet, which, with the aid of the big lock culverts, would bring the total discharge up to 262,000 feet a second—only 12,000 cubic feet less than double the highest known flow of the Chagres.

But this is only characteristic of what one sees everywhere. Whether it be in making a spillway that would accommodate two rivers like the Chagres instead of one, or in building dams with 63 pounds of weight for every pound of pressure against it, or yet in building lock gates which will bear several times the maximum weight that can ever be brought against them, the work at Panama was done with the intent to provide against every possible contingency.

The spillway through which the surplus waters of Gatun Lake will be let down to the sea level, is a large semicircular concrete dam structure with the outside curve upstream and the inside curve downstream. Projecting above the dam are 13 piers and 2 abutments, which divide it into 14 openings, each of them 45 feet wide. These openings are closed by huge steel gates, 45 feet wide, 20 feet high, and weighing 42 tons each. They are mounted on roller bearings, suspended from above, and are operated by electricity. They work in huge frames just as a window slides up and down in its frame. Each gate is independent of the others, and the amount of water permitted to go over the spillway dam thus can be regulated at will.

When a huge volume of water like a million gallons a second is to be let down a distance of about 60 feet, it may be imagined that unless some means are found to hold it back and let it descend easily, by the time it would reach the bottom it would be transformed into a thousand furies of energy. Therefore, the spillway dam has been made semicircular, with the outside lines pointing up into the lake and the inside lines downstream, so that as the water runs through the openings it will converge all the currents and cause them to collide on the apron below. This largely overcomes the madness of the water. But still further to neutralize its force and to make it harmless as it flows on its downward course, there are two rows of baffle piers on the apron of the spillway. They are about 10 feet high and are built of reinforced concrete, with huge cast-iron blocks upon their upstream faces. When the water gets through them it has been tamed and robbed of all its dangerous force. The spillway is so constructed that when the water flowing over it becomes more than 6 feet deep it adheres to the downstream face of the dam as it glides down, instead of rushing out and falling perpendicularly.

The locks are situated against the high hills at the east side of the valley, after which comes the east wing of the dam, then the spillway, then the west wing of the dam, which terminates on the side of the low mountain that skirts the western side of the valley. With the hills bordering the valley and the dam across it, the engineers have been able to inclose a gigantic reservoir which has a superficial surface of 164 square miles. It is irregular in shape and might remind one of a pressed chrysanthemum, the flower representing the lake and the stem Culebra Cut. The surface of the water in this lake is normally 85 feet higher than the surface of the water seaward from Gatun and Miraflores. The lake is entirely fresh water supplied by the Chagres River. The accompanying figure shows the profile of the canal.