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182 cent, of the vessels navigating the high seas are less than six hundred feet long." You will notice that each leaf of a pair of these gates is sixty-five feet long, instead of fifty-five or half the width of a lock. When they are closed, they form a blunt wedge pointing upstream, and the pressure of the water only keeps them tighter shut. Finally, if all the gates were swept away, there would still remain the



A—Passageway for operators.

B—Gallery for electric wires.

C—Drainage gallery.

D—Culvert in center wall.

E—Culverts under the lock floor.

F—Wells opening from lateral culverts into lock chamber.

G—Culvert in sidewalls.

H—Lateral culverts.

"emergency dam" at the head of each flight of locks, ready to be swung round and dropped into position like a portcullis.

Once a ship is inside, the lower gates will be closed behind her by machinery hidden in the square center-pier, valves will be opened, and water from the lake will rush down the conduits in the walls and flow quietly in from below, until it has reached the level of the lock above. Then the upper gates will open, and the electric locomotives,—there will be four of them to handle every big ship, one at each corner,—will go clicking and scrambling up the cog-tracks carried on broad, graceful arches