erty which was a respectable waterfall for three months of the year and a mere apology for one during the remaining nine. So from the ends of the earth he summoned men whose business it was to remedy such things-always and only Americans. From the harbor works at Esquimalt and the electric plants at Rio, from the reclamation projects in Babylonia and the barrage at Assuan they came brown-faced, wiry, confident

men in flannel shirts and sombreros, who lost not a moment in driving their stakes and getting their bench-marks and running their levels, for the conversion of a watershed, the alteration of the surface of a state, had begun. In other lands, under different conditions, the maximum water power available the year round is generally regarded as equal to the minimum flow of the stream. But in Mexico, where there is a rainy season, when vast quantities of water fall, and a dry season, with practically no

rain, the water question is largely one

of the conservation of the rainfall of the wet season as an insurance against the dry months which always come. Such was the problem, then, which faced the engineers at Necaxa and which they answered by the construction of three enormous reservoirs, having a combined capacity of five billion cubic feet of water, formed by building three great earthen dams at various points in the Necaxa valley. By means of these dams, the full rainfall, amounting to something over 135 inches during the year, is caught and stored away against the time when no rain falls, just as a great factory stores away coal to keep it in operation through times of shortage and strikes.

That the entire rainfall of the watershed might be conserved, more than one hundred and fifty streams were diverted from their normal channels by means of canals and diversion tunnels, into a system of reservoirs covering more than six thousand acres, the lower reservoir alone, if full, being large enough to run the plant for two and a half months with no water in the stream at all—a sufficient reserve for the driest recorded years. The volcanic formation of the valley making an unreliable base for stone dams, the engineers decided on earthen dams for all locations, building them by the same method of sluicing which has been used so successfully in the Western States since its efficiency was demonstrated in hydraulic mining. The water is brought in by means of sluice ditches high on the hillsides, and with the head thus gained earth and stones are washed into pipes laid on scaffolding, which carry the water and sediment to the dam site, where, against "toes" built of masonry, it is deposited and the water run off, the heavy material staying at the outside and the lighter settling slowly in the center of the dam. The largest of these dams, known as the Necaxa, is the highest earth dam in the world, exceeding by seventy-nine feet the much advertised Gatun dam at Panama. Figures are dry things at best, but some idea of its immense size may be gained from the statement that it is more than half the height of the Washington Monument, nearly twice the length of the National Capitol, and cost more than a million

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The first great problem which confronted the engineers at Necaxa was the tremendous one of getting their material on the ground, for at that time the base camp was fifty miles from the nearest railway. Two thousand feet below the base camp lay the mesa, or mountainwalled tableland, which had been selected for the reservoir sites; and sixteen hundred feet below the mesa, at the bottom of a gorge with perpendicular walls of rock, was the location decided upon for the power-houses. By an immense expenditure of time and labor the engineers succeeded in constructing a highway from the camp down to the mesa in the belief that their structural material could be transported over this road on wagons drawn by traction engines. But with the rainy season came the mountain torrents, and such portions of the road as were not completely swept away were left impassable with mud. So the men in the flannel shirts tightened up their belts and took a long breath, as it were, and attacked the seemingly unsolvable problem of building a railway down a mountainside where a goat found it dangerous to venture. Eventually the railway was completed, however, and there is not its like in all the world. Its curves are really corners and its gradients hair-raising drops. For close on thirty miles this preposterous railway twines in and out, backwards and forwards, clinging to the face of the precipitous cliffs like a fly on a wall. Ninety-seven per cent of this amazing line is curvature, and on one section there is a grade of thirty-three per cent. So abrupt are the curves that they can be negotiated only by Shay engines, the cars, each of which is manned by two brakemen, being kept apart by couplings six feet in length. One's first sensation at Necaxa is provided by the descent into the valley strapped to the front of an engine. So sharp and sudden are the curves that the frightened passenger shuts his eyes and murmurs a prayer as the engine heads straight for the edge of a precipice, hovers for a terrifying instant on the dizzy brink, and then sheers sharply to one side like a frightened horse, only to repeat the hair-raising performance again and again, until beads of cold sweat

At the terminus of the railway lies the great construction camp; row on row of well-kept streets flanked by lines of wooden huts; on a knoll overlooking the mesa the picturesque stone bungalows of the officials and engineers; close by the roomy hospital with its genial German surgeon and his corps of white-clad assistants-for in such an undertaking are many accidents;-and, of more immediate interest than all else to the hungry visitor, the long, low guest-house with silent-footed China boys setting tables

THE GREAT

and opening bottles on its rose-embowered verandas. It is more than likely, however, that the visitor would lose his appetite if he knew the afternoon's entertainment that was in store for him, for the coffee cups have scarcely been taken. away when a message comes that the cages are waiting. That in itself sounds sufficiently ominous, but when you are

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by President Diaz, together with VicePresident Corral and a large party of government officials. For a single instant, as he was about to step onto the cage, the grim old dictator hesitated. "Who is running the engine?" he asked. "An American," was the reply. "Good," said the President, "then I will descend. But you, Ramon," turning to Vice-President Corral, "had better come down on the next trip. It is not wise for both of us to go down on the same platform. Acci-. dents sometimes happen." That the

a tiny platform which swings out over the abyss on a slender wire, you are likely to have a shivery sensation creep up your spine. A few months before he went into exile, the Necaxa plant was visited

President was not going to have any accident happen to him, if he was able to prevent it, was shown by the four rurales who stood, with drawn revolvers, around the man who ran the engine while

General Diaz was descending. No accident marked his visit.

The great white building which lies in the bottom of the canon, sixteen hundred feet below the level of the mesa, is the largest power plant in the world under one roof, it being doubly remarkable when it is remembered that every brick, every girder, and every barrel of cement used in its construction was lowered from the rail-head into the barranca by means of the flimsy-looking aerial hoist which I have just mentioned. The transportation of machinery, which in several instances weighed upwards of seventeen tons, through half a mile of space, by means of platforms running on a seven-eighths-inch cable, at an incline.

only thirty degrees from the perpendicular, was a feat so daring in its conception as to be pronounced impossible by all the foreign engineers who were consulted on the subject.

It is not until one has reached the power-house, which from above looked so small and insignificant in its mountain setting, that one appreciates the true magnitude of this gigantic undertaking and marvels at the success of the promoters in finding even one spot so admirably adapted to great power development no less than at the daring of the men who have done the work. The present power plant is a steel-and-concrete structure containing six generators of 8,200 horsepower each, and four of 16,000