exposed to the hot gases is lined with a high grade of fire brick. The
back of the setting, where the rear cleaning is done, is provided with
a sliding floor plate, which is used when the upper tubes are being
cleaned. There is also a door at the floor line and another at a
higher level for light and ventilation when cleaning. Over the tubes
arrangements have been made for the reception of superheating
apparatus without changing the brickwork. Where the brick walls are
constructed, at each side of the building columns at the front,
cast-iron plates are erected to a height of 8 feet on each side of the
column. An air space is provided between each cast-iron plate and the
column, which is accessible for cleaning from the boiler front; the
object of the plates and air space being to prevent the transmission
of heat to the steel columns.

An additional feature of the boiler setting consists in the employment
of a soot hopper, back of each bridge wall, by which the soot can be
discharged into ash cars in the basement. The main ash hoppers are
constructed of 1/2-inch steel plate, the design being a double
inverted pyramid with an ash gate at each inverted apex. The hoppers
are well provided with stiffening angles and tees, and the capacity of
each is about 80 cubic feet.

In front of all the boilers is a continuous platform of open-work
cast-iron plates, laid on steel beams, the level of the platform being
8 feet above the main floor. The platform connects across the firing
area, opposite the walk between the batteries, and at these points
this platform is carried between the boiler settings. At the rear of
the northerly row of boilers the platform runs along the partition
wall, between the boiler house and operating room and at intervals
doorways are provided which open into the pump area. The level of the