REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


 The prices for submerged-rock excavation vary according to the texture and character of the rock, the price of coal, and the cost of labor, etc., in different parts of the world. The price ranges from $2.50 to $5, $6, and $7 per cubic yard.
 Mr. RIPLEY. On the St. Marys River we have moved over one million and a half yards of sandstone rock, and the price did not exceed $2 a yard in any case. A great part of the work was done for $1.50 and in some instances for less than $1. Limestone rock cost $2.43 for a contract of a little over 100,000 yards, and we now have a contract for 1,750,000 yards in the dry, which will cost $1.36 a yard.
 Mr. BATES. That is a little higher than on the Chicago Drainage Canal. The average price there was $1.10.
 Mr. RANDOLPH. No; you are mistaken, the average cost was 76 cents.
 Mr. BATES. I am glad to accept the correction.
 Mr. RIPLEY. As I understand your statement, the excavation of rock by the submerged process is from five to ten times as much as it would be in the dry.
 Mr. BATES. No, sir; five to ten times as much as ordinary dredging. Thus, for instance, the average price of dredging would be 25 cents.
 Mr. RIPLEY. I thought you were referring to dry excavation of rock.
 Mr. HUNTER. I understood you to say that, too. I thought that you said that the removal of rock under water cost five times as much as the removal of rock in the dry.
 Mr. BATES. No, sir.
 Mr. Hunter then spoke about several millions of cubic yards of rock to be removed in the Manchester Ship Canal at an ultimate depth of ,29 feet, and that the cost, figured according to a certain method which had been adopted, would be just under 50 cents a yard.
 Mr. BATES. Then you are using the Lobnitz system, which I am just about to introduce in the Hudson River. It is very applicable to sandstone rock.
 I would hesitate to place an estimate upon a Lobnitz machine, where I had to deal with 100 million cubic yards of material wherein I had to handle isthmian rock, because the best of these machines are only able to average about 20 cubic yards per hour, and while the operating cost may be similar to that quoted, the plant installation to deal with 100 million cubic yards of submerged rock would be stupendous.
 Mr. HUNTER. That is only a matter of multiplication of units, which is only a matter of detail.
 There was one point that I noted when I read this pamphlet, which I did as carefully as I could. It is a little difficult to remember it all. It is somewhat merciless in its detail, but one of the fundamental points in your argument is, as I understand the pamphlet, that the basins which you propose to create by the action of the dams, whether at Gamboa or at Ahajuela, shall always be kept empty.
 Mr. BATES. Except as to the silt ponds.
 Mr. HUNTER. Do you rely upon the emptiness of the basin?
 Mr. BATES. No, sir.
 Mr. HUNTER. I will tell you my difficulty. It seems to me that your empty-basin system would be effective and suitable for this purpose if it were empty when the flood came, but suppose that you had two storm floods in succession-that you had two floods so near together that you could not discharge the first before you were troubled with the second. That was the difficulty.
 Mr. BATES. Here, sir, is the point. When you have a divided channel you have, say, 16,000 square feet of waterway. At the velocity of 3 feet a second you could discharge 48,000 cubic feet per second, meaning a velocity of 1.7 knots per hour.
 I will admit that if you had any such double flood, one following on top of the other, you then would, for a brief period, be obliged to allow more than 44,000 cubic feet per second to pass through. You can see exactly what it means on Plate IX.
 General ABBOT. I would like to ask Mr. Bates if there is a correction necessary on page 62, as follows:
 In the present state of the art, submerged-rock excavation costs eight times as much as dry.


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