THE HISTORY OF GEOPHYSICAL PROSPECTING
PART FOUR - VISCOUNT COWDRAY

Chapter 9  -  Engineering Conquest of Mexico

The Aztec gods gave a sign to the tribe in the fourteenth century that they were to move south and raise their principal city on an island in the Valley of Mexico. Thus another Venice was born, this one 7000 feet above sea-level. This cultured and progressive Indian tribe set about building dykes and reclaiming the spaces between them. The first Aztec city, with its temples and houses all built on piles in the middle of what was then Lake Mexico, would have been a strange sight to foreign eyes if there had been any foreign eyes around.

By the sixteenth century Lake Mexico had disappeared. The water that had not evaporated had disappeared down fissures caused by earthquakes. The Aztec culture did not include any knowledge of guns and gunpowder, so that Hernando Cortes had no great difficulty in conquering the Aztecs. Spanish culture was weak on its geological fundamentals, so that Cortes missed the significance of the fact that the Valley of Mexico was an immense land-locked basin. When he built the capital of New Spain on the ruins of the old Aztec town, he failed to put the buildings on piles.

The new city grew rapidly in both population and wealth. Every twenty years or so water from the upper lakes flowed over the dykes and kept its streets under from two to six feet of water for months at a time. The drainage problem had only one logical solution. Immediately north of Lake Zumpango and thirty miles north of Mexico City, the mountain range was somewhat lover than the general level. A cut or tunnel through the mountains at this point joined up with Lake Zumpango by a canal would enable the highest and most dangerous of the lakes to have its excess water drained off into the Tula River on the far side of the mountain barrier.

In 1607 a humble printer named Martinez managed to persuade the rather reluctant authorities in Mexico City to undertake such a tunnel and put him in charge of building it. By keeping a labor force of some 15,000 Indians hard at work for eleven months the tunnel was completed. It was ten miles long, fifteen feet wide and twelve feet in height. Martinez was unable to convince the town fathers that it was necessary to line the entire tunnel with some kind of masonry. Therefore only a raw earth tunnel was prepared to meet the next floods.

In 1627 the Cuantitlan River, which flowed into Lake Zumpango, rose to flood stage and the high waters of Lake Zumpango were turned into the Nochistongo tunnel. Timber supports caved in and earth slides seriously blocked the fifteen foot channel. The result was that Lake Zumpango again overflowed the lower lakes and Mexico City was once more under water. A much worse flood came along two years later. From 1629 until 1634, six feet of water stood in the streets of the city.

The situation was relieved in 1634 by a timely earthquake which made a good sized fissure in the valley and drew off the water into the bowels of the earth. The Mexicans now turned their attention to repairing and enlarging the Nochistongo tunnel. By this time Martinez was in disgrace. When the earth again caved in, killed his workers and blocked the channel, he was cast into prison and charged with creating the obstructions which he was struggling to remove. The city officials tried hard to find someone else to guide the destinies of the tunneling but no one was willing to take charge of such a hopeless endeavor. There was nothing to be done but release Martinez from prisen and put him once again in command. This time it was decided to open an exodus with a great cut downward from the top of the mountain. The enormity of the task staggers the imagination. The building of the Pyramids was child's play in comparison. Martinez spent the last thirty seven years of his life barely making a beginning. He died without honor.

A full century passed from the death of Martinez to the successful completion of this slice through the mountain. "An estimated 200,000 man died of overwork, accident and disease; human sacrifices to the project. The surroudlng towns had their male population decimated. The largest prison in Mexico was maintained at the site of this engineering monstrosity so that prison labor was always available in quantity.

Yet for all this expenditure of time, lives and money the mountain slice when finished was only a partial success. Lake Zumpango could be handled but Lake Xaltocan and especially Lake Texcoco still flooded the principal metropolis. Lake Texcoco was thirty feet below the bottom of the gigantic cut through the mountain.

Such was the state of affairs in the fall of 1889 when Weetman Pearson talked with the personal representative of President Jose Diaz of Mexico in New York City. Mr. and Mrs. Pearson made the trip to Mexico City in December at the invitation of Diaz. Soon Pearson was engaged in four hour sessions, then eight hour sessions and finally twelve hour sessions with the President's Commission. Worn to desperation by the vicissitudes of Latin diplomacy, Pearson finally told the Commission that three contractural conditions must be met or he would withdraw from the negotiations. President Diaz, who by that time was sitting with the Commission, drew Pearson to one side, studied the Englishman's countenance for a long moment and then said to him through an interpreter that Mexico would give way on all three points if in return Pearson would assure Diaz, on his honor, that Pearson would always treat the Government in the same way that he would expect to be treated by the Government. Pearson agreed to what we might term an engineering application of the golden rule. This was the start of a close friendship between Diaz and Pearson.

The Mexican Grand Canal was built by S. Pearson and Son in the period 1890 to June, 1896. The job was performed by five specially constructed dredgers working round the clock schedules plus an enormous force of hand laborers. The total length of the canal was 29-1/2 miles, with a depth ranging up to 72 feet and a total excavation of approximately fifteen million cubic yards. At its northern end the Grand Canal hooked into a tunnel running through the mountain barriere Not only was the flooding problem solved but a means was provided for the drainage of Mexico City's sewage. A problem extending back to the Middle Ages had at long last been solved.

The digging of the Grand Canal to provide drainage for Mexico City was only the first of a series of projects performed by S. Pearson and Son for the Government of Mexico. Some idea of the scope of these Mexican operations may be gained from the following table.