The spillway further serves a useful and an essential purpose in that it harnesses the water power of the useful Chagres, and turns it into electric power to open and shut the colossal gates of the various locks; to propel the electric locomotives that tow the great ships through the concrete channels; to light the canal towns and villages, and the lighthouses on the line; to run the great cranes at Balboa and Cristobal; to run the machinery in the shops at Balboa; to furnish motive power, if so determined for the Panama Railroad, and to swing the great guns at Toro Point and Naos Island until their muzzles bear with calm yet frightful menace upon any enemy approaching from either the Caribbean or the Pacific. There will be power for all these functions, and power too to light Panama and Colon, to run the Panama tramway and perform other useful functions if the present grip of private Panama monopoly upon these public services shall be relinquished. The water drops 75 feet through huge penstocks to great turbines in the spillway hydro-electric station with a capacity of 6,000 kilowatts, but the amount of water power is sufficient for double that current, and turbines to supply the addition can be installed whenever the need for the power develops. [Illustration: THE WATER KNOCKING AT GATUN GATES] [Illustration: WALL OF GATUN LOCK SHOWING ARCHED CONSTRUCTION] The Gatun locks are built at the very eastern end of Gatun dam, at the point where it joins the mainland bordering the Chagres valley. Of their superficial dimensions I have already spoken, and have described their appearance as seen from the deck of a ship in passage. It will be hard however for one who has not stood on the concrete floor of one of these massive chambers and looked upward to their crest, or walking out on one of the massive gates peered down into their depths, to appreciate their full size. It is all very well to say that the “Imperator,” the greatest of ships now afloat, could find room in one of these locks with five feet at each side, and fifty feet at each end to spare, but then few of us have seen the Imperator and nobody has seen her in the lock. It is all very well to figure that a six story house would not rise above the coping of one of these locks, but imagination does not visualize the house there, and moreover there are stories and stories in height. Yet as one stood on the floor of one of these great monolithic tanks as they were being rushed to completion in 1913, and saw locomotives dwarfed by the ponderous walls betwixt which they plied, and whole trains of loaded dump cars swallowed up in a single lock chamber, one got some idea of the magnitude of the work. A track for a travelling crane extended down the center of the chamber and the monster rumbled back and forth carrying loads of material to their appointed destinations. Across the whole width of the Canal below the locks stretched cable carriers upheld