The Canal Route--Plans Amended.

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Since that time careful borings have been continued over the entire area in order to secure a contoured plat of the rock surface with a view to the most economical adjustment of the locks to the site. Soft sandstones of a dirty greenish-gray color, derived from igneous rocks with a calcareous and clayey cement, are the most abundant rocks of the Gatun formation. The rocks are all well consolidated, though in a few rare cases sandy layers are found which crumble on exposure to the air. These are the beds that have been referred to frequently as “indurated clays." The term is a misleading one since true clays make up but a small part of the formation. The beds are all "rock", though in some instances soft enough to be loosened with a pick. It is evident that at one time this section was entirely under water, as sea shells have been picked up on top of some of the hills. Recently a steam shovel dipper dug up at Gatun an ancient bomb at a depth of fourteen feet below the surface of the ground. How it came there is a mystery. An extensive erecting plant, cable ways, etc. will be installed at this point, for the carrying and conversion of material required for use in the locks and dam.

GATUN LAKE.-As soon as the portions of the dam abutting Spillway Hill are high enough to stand 50 to 55 feet of water in the lake, it is proposed to build across the channel through Spillway Hill, a concrete dam high enough to hold the lake at the aforementioned level. During the dry season following, the dam across the channel through Spillway Hill will be brought to its full height, and a permanent spillway constructed, including the necessary regulating works by means of which the surplus water of the lake will be passed down to the sea. It is probable the lake will not be allowed to fill to the height of 50 to 55 feet until the upper end of the Gatun locks has been erected, and the upper gates built. The area of the lake will be 164.23 square miles. Its cubical capacity is not yet known. The lake will extend all the

way from Gatun to Bas Obispo, and the towns of Lion Hill, Frijoles, Tabernilla, San Pablo, Gorgona, and Matachin will be on islands entirely surrounded by water. Between Gatun and Bas Obispo, the Chagres River crosses the center line of the canal no less than 23 times.

OVER THE DIVIDE.-The Chagres will enter the lake near Bas Obispo, and at this point the canal begins to cross the divide, by way of Culebra cut, and thence to Pedro Miguel near where the low level is again reached, a distance of about ten miles. During the past year the work of excavation in the Cut has been progressing satisfactorily. The August, 1907 excavation from the canal prism made such an excellent showing as to call forth the following congratulatory cable from the President:

Goethals, Culebra.

Oyster Bay, N. Y.,

Sept. 5, 1907.

I heartily congratulate you and all the men on the canal for extraordinary showing you have made during the mouth of August. As this is the height of the rainy season, I had not for a moment supposed you would be able to keep up your already big record of work done, and I am surprised as I am pleased that you should have surpassed it.

THEODORE ROOSEVELT.

The record for the month of August was 1,274,284 cubic yards, the highest up to that time since the canal has been in American hands, and this despite a rainfall of 11.89 inches during the month.

As the work of excavation proceeds in the heavy cuttings of the Culebra Division, the question of drainage becomes more and more important. At the north end of the Culebra Division, where the Chagres crosses the line of the canal, the elevation of the water surface of the river at dead low water is about plus 44, and during the rainy season under normal conditions about plus 49 to plus 50

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but during the great flood of December, 1906, the water surface there reached a height of plus 79.9. "It is there-fore evident," states the report of the Commission for 1907, "that when the canal is approaching completion, a barrier or dam must be placed at the northern end of the Culebra Division, near the river, to keep out the waters of the Chagres, and that the larger part of the drainage of the canal must be carried to the south, where toward the Pacific, the land slopes more rapidly. It will however, be

necessary to install centrifugal pumps in order to dispose of the water which will come down into the cut and cannot be conveniently carried off by natural drainage to the south. It is very important to divert from the canal, for construction purposes as well as for economy in maintenance after the canal has been completed, all possible water which would get into it from the adjacent watershed. is therefore proposed, during the next fiscal year, to repair and put in operation the old French diversion channel ex

It

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tending from Culebra and emptying into the Chagres on the west side of the canal below Gamboa. A survey party has been at work locating a diversion. channel for the Obispo River, and other streams on the east side of the canal, which will extend from Culebra and will run approximately parallel to the canal, discharging its waters into the Chagres near Gamboa.'

CHANGES AT PACIFIC END.-The changes at the Pacific end are the most important made since the adoption of the original plans. The Chairman's report to the Secretary of War states:-

"The adopted plan for the building of the Panama Canal contemplated the formation of a lake on the Pacific side by the construction of three earth dams (Sosa-Corozal, Sosa-San Juan and Corozal-Diablo), the differences of level between the lake and the Pacific being overcome by a flight of two locks projecting into the Pacific on the west side of Sosa Hill."

"The Board of Consulting Engineers that accompanied you to the Isthmus in April last, inspected the sites of the dams, as finally located, with a view to outlining a detailed description of the preparation of the foundations for the structures to be erected, reporting thereon as follows:-

"The borings showed so-called mud in the swampy portion, having a depth of 8 or 10 feet. This material is firmer than we had expected, and at the time of our visit, about two days after it had been flooded by spring tides,it could be walked on in most places......For the dam construction .....we do not think it will be necessary to remove the soft material at any of these places (Sosa-Corozal, Sosa-San Juan). The very softest material will either be displaced or consolidated by the material disposed on it. We do not think the amount displaced beneath the impervious portion of the embankment will be great, and if compressed in place the material will be impervious."