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Mr. WALLACE. No, sir.

Senator MORGAN. At the deepest of those borings, or at some of them, did they reach through the indurated clay and into a softer mass of material?

Mr. WALLACE. No. The borings only went down into the indurated clay far enough to be sure they were in that material. In some of those places there were other kinds of clay on top of the indurated clay, and in order to determine that the clay was indurated clay the borings went some distance into it in some places; but there was no attempt ever made to go through it.

Senator MORGAN. There is nothing below the indurated clay of softer material?

Mr. WALLACE. The borings did not go far enough to show what there was below the indurated clay.

Senator MORGAN. Not even in that deepest part?
Mr. WALLACE. No, sir.

Senator MORGAN. At the lowest depth of that deepest fissure there into which borings were made you still found the indurated clay?

Mr. WALLACE. Yes, sir.

Senator MORGAN. This blueprint shows that tubes were driven down, like the tubes of an artesian well, for the purpose of determining whether water would flow through them as the borings descended; and it was found that at this heavy line which is here, which I believe indicates sea level or just below that, and at the same elevation almost in each of these borings the water poured out of the tubes. Would that indicate that that water was at a level between those points where it poured out of the tubes, and that that level was maintained either through this indurated clay in this insular place or went around it?

Mr. WALLACE. It would indicate that that water was connected with other water at a higher elevation, and that it was freely flowing through the material that the water came through.

Senator Morgan. That was taken, I suppose, as satisfactory evidence that in some way the mass of water that was flowing out of the tubes in each of these gorges was a continuous body?

Mr. WALLACE. Yes, sir; and a continuous stream, and that the material in the part of the gorge to which that tube ran was what we call freely water-bearing.

Senator MORGAN. Have you any idea, or have you any reason to suppose or to believe that the water which rose at equal heights in these tubes in these respective deep gorges ran through the body of indurated clay or ran around it?

Mr. WALLACE. From the data that has been presented I would judge that the water followed these gorges, and, if the clay was indurated, that the water was confined to the

gorges. Senator MORGAN. That it was confined to the gorges and ran around this insular place that had been washed out on both sides?

Mr. WALLACE. Yes, sir.

Senator MORGAN. In building the dam upon the top of that material, say, 30 or 40 feet below the surface of the earth, to span each of these gorges, that dam would rest upon material more or less permeable and more or less soft, including wood or other stuff. In order to make that dam secure, would it be necessary to shut out or close

out permanently this conduit that supplied water from a common source and that ran either through or around this insular position ?

Mr. WALLACE. Yes; it would be necessary to cut it off.

Senator MORGAN. By what means could that be cut off ? By what known engineering means could it be cut off ?

Mr. WALLACE. That same question practically was asked me a while ago, Senator, only not in that particular form, and I said then that it might be possible to cut it off, but I would not undertake to do it if I was an engineer of that work if I could find any place else to build my dam.

Senator MORGAN. Is there any certain known engineering formula or proceeding or process by which that water could be cut off other than by taking out the material down to and below it and starting the foundations of your dam below the point where this water flowed ?

Mr. WALLACE. The way you have suggested would be the most thorough way to do it; but I have never known it to be done at such great depths as that.

Senator MORGAN. Very good.

Mr. WALLACE. About 100 to 110 feet below the surface of the water is about the maximum depth to which you can go down and clean off material and build up and about it. Of course there are processes by which you could drive sheet piling at some greater distance, or inject cement, or use the freezing process, and all that sort of business; but the depths of that, the success and utility of it, would be, to say the least, doubtful.

Senator MORGAN. If I understand the project of the minority of the consulting board of engineers, they propose first of all, in constructing this dam, to go down and take off the softer material that lies on the surface of the earth until they get down to about the general level of the indurated clay; then they propose the construction of an earth dam upon that basis to span both of these gorges. Is that a correct assumption?

Mr. WALLACE. That is the way I understand it.

Senator MORGAN. A dam constructed in that way, and leaving the material as it is in these two deep gorges, would rest upon a body of earth or body of material through which and below which there is now an actual flow of water. I want to know if a dam constructed in that way and at the levels that I have been describing can be made to stop that flow of water; can it be done otherwise than merely through the pressure of the weight of the superstructure of the dam upon the underlying material?

Mr. "WALLACE. In my opinion the weight of the superstructure of the dam would not shut it off.

Senator MORGAN. It would not?
Mr. WALLACE. No, sir.

Senator Morgan. Is there any other way to do it, except through the weight of the superstructure?

Mr. WALLACE. In that form of construction, no; and, as outlined in their plan, no.

Senator MORGAN. That is the plan that is recommended for the dam?

Mr. WALLACE. As I understand it; yes, sir.

Senator MORGAN. If the superstructure of the dam, the earth part that is filled in and superimposed upon this foundation there that I

have been trying to describe, by its weight and pressure closes up ultimately this water flow, would that not be done at the expense of irregular settling in the dam? Mr. WALLACE. Yes; but it would not close up the water flow.

Senator MORGAN. I know you think it would not. I am assuming the possibility that it should do it.

Mr. WALLACE. It is rather a hard presumption.

Senator Morgan. Would it not be done at the expense of, I will say, the integrity of the dam above, so that it would sink!

Mr. WALLACE. Yes; but, Senator, in my view, you will have two things that will happen there.

Senator MORGAN. What are they?

Mr. WALLACE. The first thing is negative, and that is, that in my experience I have never yet seen weight that is superimposed on water-bearing stratification of gravel that was fully saturated ever have any tendency to shut off the water, because you can not compress it. There are voids there, and the gravel and the sand and the stone make arches.

Senator MORGAN. The water itself is incompressible?

Mr. WALLACE. And the water itself is incompressible, of course. Near the surface where you have any vegetable deposits you will have settlement, and you will have compression. But those are not the strata through which the water flows, but those are the ones that will compress, and the result will be a tendency for that dam to crack on lines perpendicular with the edges of these gorges.

Senator MORGAN. To have fissures?

Mr. WALLACE. Yes, sir; and those fissures will have a tendency to let the water through them, and will have a tendency toward weakening the structure.

Senator MORGAN. If a fissure should form in this dam, perpendicular, I will say, to either of these gorges, or between their borders, between their walls, would not such a fissure as that endanger the sweeping out of the entire structure from end to end when the water was at a height of 80 or 85 feet?

Mr. WALLACE. It would have a tendency to make a break in the dam where these fissures occur.

Senator MORGAN. When a fissure occurs under a head of 80 or 85 feet of water

Mr. WALLACE. It is generally disastrous.
Senator MORGAN. Disastrous ?
Mr. WALLACE. Yes.
Senator MORGAN. Can it be otherwise?

Mr. WALLACE. Of course I would not like to say that that thing would actually occur at that point.

Senator MORGAN. No; we do not any of us attempt to say what will occur in the future.

Mr. WALLACE. But I would not take the chances on it.

Senator MORGAN. That, then, is one of your material objections to the construction of this dam, if I understand you?

Mr. WALLACE. Yes.

Senator TALIAFERRO. You favor the sea-level canal, I see by your article?

Mr. WALLACE. Yes, sir.

Senator TALIAFERRO. Do you favor the plan as laid down by the Board of Consulting Engineers?

Mr. WALLACE. Well, in general—that is, as far as the main canal is concerned, its alignment, and its general size, etc. The only two points in their report that I would be disposed to question—not to criticise, but to question until I could give it more deliberate consideration than I have been able to with the other duties that I have had to perform—has been whether or not it would be advisable to go through between Ancon and Sosa on the Panama side and construct that new channel or simply to enlarge the present canal channel up La Boca way.

Also, I am not thoroughly satisfied from the examination I have made of it as to whether these longitudinal breakwaters are better than it would be to put this breakwater across here, according to the old plan. I have my doubts about that. But that is a detail, compared to some of these other questions, of course.

Senator KITTREDGE. Is the change of the channel at the La Boca end a matter of detail as compared with the other matters?

Mr. WALLACE. Yes, sir; the present channel is around this way [indicating on map]. Of course this makes a straighter shoot out to sea, and so is a little better, that is true; but there is a great deal of rock through here [indicating), and evidently one idea of their coming down here was to get the tidal lock in here (indicating], instead of up here at Miraflores where it was originally planned.

The CHAIRMAN. What do you think of the width of the sea-level canal for business for the future?

Mr. WALLACE. It is so much larger than anything that exists, than the Suez or any other maritime canal of the world to-day, that it seems to me that it would be ample for the start. Up to San Pablo, and possibly to Obispo, it would cost comparatively little to give you an extra 100 feet in width, if you ever wanted it, in these earth sections.

Senator TALIAFERRO. How about the Pacific side as to extra width?

Mr. WALLACE. Up to San Pablo I would say, in round numbers, that you could get an additional 100 feet in width for not to exceed $10,000,000, if you wanted it. That is on the sea-level proposition.

The CHAIRMAN. From that to the Caribbean Sea ?

Mr. WALLACE. Yes, sir. And it would be possible to widen the section with moderate expense from there up to Obispo. But this section, of course, from Obispo through to Pedro Miguel, would be common to all your various plans, no matter what their height, on account of the heights of the ridges. From Miraflores down to the sea, two or three million dollars ought to give you your additional 100 feet. There are some lumps of basalt that come up in here [indicating on map] where you might have to make some rock excavation under water, but I do not think they are material. So that you would have very little difficulty in getting any width that you wanted up to Miraflores.

Senator TALIAFERRO. From Panama Bay to Miraflores, what do you estimate that it would cost for a width of 500 feet?

Mr. WALLACE. I could not tell you unless I went into the figures and examined them carefully. It would not be prohibitive at all. It would be very moderate.

Senator TALIAFERRO. With a 500-foot canal from the Pacific to Miraflores, would it be necessary to use the tidal lock?

Mr. WALLACE. No, sir.
Senator MORGAN. You say it would not?

Mr. WALLACE. No, sir. The channel now is very narrow up here to La Boca. This channel you see here [indicating on map), although it is out in the bay, is practically in the canal, and there is no trouble at all in navigating this at all stages of the tide up to here [indicating]

Senator MORGAN. I want to ask about that for just a moment. If I understand you correctly, now, a sea-level canal 500 feet wide and 40 feet deep of prism would dispense entirely with the necessity for a sea-gate, if that was extended, you say, to Miraflores?

Mr. WALLACE. Yes, sir.
Senator MORGAN. There would be no occasion for a sea-gate at all?

Mr. WALLACE. No, sir; there would be no occasion for a sea-gate between that point and Miraflores. Of course, if you have a narrow channel through Culebra, the probabilities are that you would have to have a sea-gate in there at some place; but no engineer, Senator, has ever yet been able to make any calculation to determine what the velocity of the currents would be due to an open canal without any tidal locks. They can not answer that question. I can not, I will admit it.

Senator MORGAN. That depends upon fluctuations of the winds and all that on the ocean?

Mr. WALLACE. The uncertain element is this: It depends on the relative size of the different sections of the canal in regard to each other. As a rule, what creates a high tide is a funnel-shaped entrance of a bay. That is, the ordinary tides come into it, and then being confined, pressing up, and rising, and making a curve of that nature [illustrating], of course, over a very long distance. That is what makes the extraordinary tides in the Bay of Fundy. And it is the general shape of Panama Bay that creates the high tides there at Panama. The effect of tide on the canal would depend a good deal on the sequence of the shapes of your channel. And if you had a long channel of absolutely uniform width the effect of that tide would be very soon dissipated on account of the friction of the water on the sides of the canal.

Senator TALIAFERRO. So that if you had a sea-level canal of 400 or 500 feet width from ocean to ocean there would be no necessity

Mr. WALLACE. There would be no necessity for any tidal locks at all.

Senator MORGAN. It would take an ocean of money to build it, though.

Mr. WALLACE. If you had a canal of any width so that two ships could freely pass each other-I mean under a speed of 4 or 5 miles an hour-you would not have any necessity for any tidal locks.

The CHAIRMAN. Do you think large ships, the largest ships that are being built now and that are already built, could pass at a speed of 4 or 5 miles an hour in a waterway 150 feet wide?

Mr. WALLACE. Not both of them. The ordinary practice would be to tie one of them up.

The CHAIRMAN. One of them would be tied up?

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