WEST CHAMBER OF

GATUN UPPER LOCKS, LOOKING SOUTH, SHOWING UPPER GUARD GATES UNDER CONSTRUCTION, JULY, 1911.

into three stories, or galleries. The lowest gallery will be for drainage; the middle, for the wires that will carry the current to operate the gate and valve machinery, which will be installed in the centre wall; and the upper will be a passageway for the operators. The lock chambers will be filled and emptied through lateral culverts in the floors, connecting with main culverts, 18 feet in diameter, in the walls, the water flowing in and out by gravity.

The lock gates will be steel structures 7 feet thick, 65 feet long, and from 47 to 82 feet high. They will weigh from 300 to 600 tons each. Ninety-two leaves will be required for the entire Canal, the total weight being 57,000 tons. Intermediate gates will be used in the locks, in order to save time and water, if desired in locking small vessels through, the gates being so fixed as to divide the locks into chambers 600 and 400 feet long respectively. Ninety-five per cent of the vessels navigating the high seas are less than 600 feet long. In the construction of the locks it is estimated that there will be used approximately 4,500,000 cubic yards of concrete, requiring about the same number of barrels of cement.

No vessel will be permitted to enter or pass

through the locks under its own power. Electricity will be used to tow all vessels into and through the locks, and to operate all gates and valves, power being generated by water turbines from the head created by Gatun Lake.

The time required to pass a vessel through all the locks is estimated at three hours, one hour and a half in the three locks at Gatun, and about the same time in the three locks on the Pacific side. The time of passage of a vessel through the entire Canal is estimated as ranging from ten to twelve hours, according to the size of the ship, and the rate of speed at which it can travel.

The total excavation, dry and wet, for the Canal, as originally planned, was estimated at 103,795,000 cubic yards, in addition to the excavation accomplished by the French companies. Changes in the plan of the Canal, made subsequently by the order of the President, increased the amount to 174,666,594 cubic yards. Of this amount, 89,794,493 cubic yards were to be taken from the Central Division, which includes the Culebra Cut. Active excavation work on a large scale did not begin until 1907, when 15,765,290 cubic feet were removed. In 1908,

over 37,000,000 cubic yards were removed, and in 1909, over 35,000,000, making a total for the two years of over 72,000,000 cubic yards, or a monthly average for those two years of 3,000,000 cubic yards. The total of those two years was nearly half of the entire excavation for the Canal. On April 1, 1910, the excavation exceeded 103,000,000 cubic yards, nearly the entire amount called for in the original plan. The French companies had excavated 78,146,960 cubic yards, of which 29,908,000 cubic yards were useful in the present plan of construction. The statement, which was issued in the first half of 1910, contains a summary of expenditures, which makes interesting reading when compared with the similar statement of the Panama Canal Company.