sections were completed, the caisson was sunk, by water ballast, to a
bearing on the pile foundation.

Adjacent to the condensing water conduits is the 10 x 15-foot
rectangular concrete tunnel, through which the underground coal
conveyor is installed between the shore end of the pier and the power
house.

[Sidenote: _Steel Work_]

The steel structure of the power house is independent of the walls,
the latter being self-supporting and used as bearing walls only for a
few of the beams in the first floor. Although structurally a single
building, in arrangement it is essentially two, lying side by side and
separated by a brick division wall.

There are 58 transverse and 9 longitudinal rows of main columns, the
longitudinal spacing being 18 feet and 36 feet for different rows,
with special bracing in the boiler house to accommodate the
arrangement of boilers. The columns are mainly of box section, made up
of rolled or built channels and cover plates. They are supported by
cast-iron bases, resting on the granite capstones of the concrete
foundation piers.

Both the boiler house and the engine house have five tiers of floor
framing below the flat portion of the roof, the three upper tiers of
the engine house forming galleries on each side of the operating room,
which is clear for the full height of the building.

The boiler house floors are, in general, framed with transverse plate