The Panama Canal: A history and description of the enterprise

by J. Saxon Mills

The broken stone which is one of the ingredients of concrete was quarried and transported from Porto Bello—a name famous in the annals of West Indian romance—20 miles to the east of Colon; while the sand came mostly from Nombre de Dios, also a celebrated place 20 miles further to the east, the Atlantic terminal of the old paved trans-isthmian road along which the Spanish mule convoys brought the silver of the Incas from Panama. Millions of yards of stone came from Porto Bello. Hundreds of bargeloads of sand came from Nombre de Dios and from islands in the Atlantic and Pacific. Myriads of barrels of cement were shipped from the United States to Cristobal, an outskirt of Colon, thence carried by barges to Gatun or by railway to the Pedro Miguel and Miraflores lock sites. Dozens of mighty "mixers" were ready to receive these diverse materials. Each of these could accommodate ten tons of sand, cement, crushed stones, and water. This indigestible mixture the machine would toss and churn round for a minute or so in its interior and then belch it all out in the shape of unhardened artificial stone.

The belief in concrete among the builders of the Panama Canal has been almost a superstition. They invented a sort of cement gun to shoot sand and water against the sides of the Culebra Cut, so as to form a coating of solid artificial rock, but the experiment rather deserved than achieved success. Of course all such structures as lighthouses were built wholly of concrete, and it is reported that even barges were constructed of this adaptable material. As regards concrete and its nature and behaviour nothing was taken for granted. Every means was taken of testing such important matters as the effect of sea-water on this material, the time it takes for these huge masses of artificial stone to settle, and many other questions on the answer to which the permanence and stability of the locks and the entire waterway would depend. The Panama Canal, writes Mr. Showalter, is "the greatest effort man ever has made, and perhaps ever will make, to simulate the processes of geologic ages, and do in days what Nature required unreckoned years to accomplish."

These remarks about concrete naturally lead us to the subject of the Panama locks, the magnificent stairway at Gatun, the single-step locks at Pedro Miguel (or, as the worker quickly Anglicized it, Peter Magill), and the double-step flight at Miraflores. The most impressive of these is the colossal duplicated three-step flight at Gatun, up which the vessel in transit is lifted from the end of the sea-level seven-mile-long entrance channel through Limon Bay to Gatun up to the surface of Gatun Lake, 85 feet above the level of the sea. This giant staircase has been constructed in a cutting through the hill which retains at this end the waters of the artificial lake. A tremendous amount of excavation, upwards of 5,000,000 cubic yards, was necessary, and the locks, which are constructed entirely of concrete, contain about 2,046,100 cubic yards of that material. The chambers of all the locks in the canal will have a usable length of 1,000 feet and a width of 110 feet. These dimensions should prove large enough for the largest ships not only existing but likely to be constructed for many years to come. They satisfy the requirement of the Spooner Act that the canal shall be "of sufficient capacity and depth to afford convenient passage for vessels of the largest tonnage and greatest draft now in use, and such as may reasonably be expected." More than 95 per cent. of the ships now afloat are less than 600 feet in length, so that a good margin is allowed. We may be certain that the American government has given the closest attention to the question of the length and breadth of the lock-chambers, for the canal, we must remember, is primarily a military passage for the purpose of transferring, if need be, the entire American fleet from the Atlantic to the Pacific seaboard. The locks of the Kiel Canal, it may be added for purposes of comparison, have an available length of 492 feet and a width of 82 feet.

The vessel, then, in order to gain the level of Gatun Lake from the Atlantic entrance, has to pass through a flight of three successive locks. The maximum lift is 32 feet, or about four feet higher than at any other locks now in use. All the locks along the Panama Canal are duplicated—that is, there are two parallel sets with a common centre-wall—so that two ships could be simultaneously put through both flights in the same or in opposite directions. This "double-tracking" is in itself one of the many precautions taken against accidents at the locks. There are no locks in the world where these precautions are so minute and numerous. It is all of course in the interests of the owners to inspire the maximum of confidence in maritime circles. Complete efficiency in the operation of the canal, absolute safety for the vessels and cargoes entrusted for ten or twelve hours to its keeping, are the elementary conditions of success. Each lock through which the vessel passes is equipped with two pairs of mitre gates—that is, double swinging doors—the biggest lock-gates in the world; but in all cases the uppermost locks have a second pair of gates, so that if some unruly vessel were to ram open one set of gates there would still be another set ready to receive it. But even this is not all. Heavy chains are stretched across the channel with the ends attached to hydraulic paying-out machinery. These chains and their attachments are capable of bringing to a dead stop a vessel of 10,000 tons moving at the rate of five miles an hour. And still the precautionary devices are not exhausted. Let us suppose that all these barriers were broken down, though such a disaster is almost beyond the bounds of things possible. At the head of each flight of locks there are provided great cantilever swing-bridges which can be thrown across the channel in case of accident. From these bridges a series of nickel-steel wicket girders could be let down. The lower ends of these girders would drop into a sort of sill at the bottom of the rushing waters. The girders would then act as small perpendicular runways, down which large steel sheets on rollers would be let down, gradually damming back the escaping waters.

And lastly, in order to avoid all recourse to these emergency contrivances, it is ordained that no vessel shall enter any chamber of any locks under its own steam. Nearly all the accidents that happen in locks are due to the vessels being worked independently of the lock authorities when passing through. Captains may be as anxious as possible to avoid mistakes, but there is many a slip possible between an order and its fulfilment. So the lock operators are not going to be responsible for the safety of a vessel which is not entirely under their own control. None will be allowed to negotiate the locks under its own motive-power. A series of electric towing-stations will be set up on the side walls of the locks. When a vessel approaches it will be brought to a standstill outside the locks. Then four of these towing engines will be fastened to it by means of hawsers—two at the stem, in order to draw the vessel into the locks, and two at the stern, to check its speed and bring it to a standstill when necessary. And this control will of course be exercised all through its passage to the upper or lower levels. We should certainly not hear of any accidents in the lock-chambers of the Panama Canal.

Gatun Locks, looking South-West, showing North End of the Locks.

It is expected that a vessel will be passed through the three locks at Gatun in about fifty minutes, though some delay may be caused in the approach. On the Atlantic side the water of the canal will be smooth, and the ship will be in some degree sheltered from the winds, so that there should be no difficulty in the approach from that direction. Coming from Lake Gatun to the locks the vessel may experience a little rough water, though there is seldom a great force of wind there, and the lake will be free from currents. As regards the Pacific side, the ocean there fully corresponds with its name. It is always calm, and not the slightest difficulty may be anticipated from either winds or waves or currents.

Over thirty miles away at the southern extremity of the Culebra Cut the vessel in transit will be lowered from the high-level lake 30 feet down to the surface of another artificial lake much smaller in content, held at a surface-height of 55 feet above sea-level. These are the single-step duplicate locks known as the Pedro Miguel or "Peter Magill." The construction of these locks required 770,000 cubic yards of cement. On the west side of these locks is the other dam which, with the mighty Gatun dam at the other end, holds up the waters of Lake Gatun. This smaller dam is also of earth, and is about 1,400 feet long and 40 feet wide at the top. It is subjected to a maximum "head" of water of 40 feet, but the average is from 25 to 30 feet. The length of the lake, which is known by the pretty name of "Miraflores," between the Peter Magill and the next set of locks, is about 2,000 yards, and the lake itself covers about 1,200 acres. Its waters are held up at 55 feet above sea-level by two dams at the Miraflores locks.