enced. The engines have cylinders of twelve feet diameter,
and are capable of lifting 2,000,000 tons of water in twenty-four hours
from the depth of seventeen feet to the level of the _boezem_, or
catch-water basin, of the district. The boezem carries the water to the
sea, into which it discharges by sluices at Katwyk on the North Sea and
at Sparndam and Halfweg on the Y, or the southern end of the Zuyder Zee.
The land reclaimed is now in excellent tillage, and one farm on the
tract is referred to in agricultural journals as one of the three model
farms of the world. The three engines are called the Leeghwater, the
Cruquius and the Lynden, from three celebrated engineers who had at
different times proposed plans for draining the Haarlemmer Meer.
Proposals for its drainage were made by one of these engineers as far
back as 1663. The next enterprise in hand is the drainage of the
southern lobe of the Zuyder Zee, which is stated to have an average
depth of thirteen feet, and it is intended to cut it off by a dike from
the northern basin and erect sufficient engines around it to pump it out
in thirteen years at the rate of a foot a year, working night and day.

Another engineering device, very necessary in a land where foundations
are so frequently built under water, is the enclosed caisson with
compressed air, as shown in detail in this exhibit. It was originally
invented by M. Triger to keep the water expelled from the sheet-iron
cylinders which he sunk through quick-sands in reaching the
coal-measures in the vicinity of the river Loire in France. The seams of
coal in this district lie under a stratum of quicksand from fifty-eight
to sixty-six feet in thickness, and they had been inaccessible by all
the ordinary modes of mining previously practised. The system has been
much amplified and improved since, especially in sinking the foundations
of the St. Louis and the New York East River bridges, and does not
require specific description. An improved air-lock, by which access is
given from the exterior to the working chamber at the part where the men
work in an atmosphere sufficiently condensed to exclude water from the
lower open end--like a tumbler inverted in water--is the principal
addition which America has made to the device.

We need not go abroad to find long bridges, but the great bridge, with
three immense iron trusses and eight smaller ones, over the Wahal near
Bommell would be respectable anywhere. Our Louisville