d by timber bracing, having
its bearing on the street surface and the tunnel timbers. The
permanent support will be masonry piers built upon the roof of the
subway structure. Along this portion of the route are street surface
electric roads, but they are operated by overhead trolley and the
tracks are laid on ordinary ties. It has, therefore, been much less
difficult to care for them during the construction of the subway. Work
is being prosecuted on the Brooklyn Extension day and night, and in
Brooklyn the excavation is made much more rapidly by employing the
street surface trolley roads to remove the excavated material. Spur
tracks have been built and flat cars are used, much of the removal
being done at night.

CHAPTER III

POWER HOUSE BUILDING

The power house is situated adjacent to the North River on the block
bounded by West 58th Street, West 59th Street, Eleventh Avenue, and
Twelfth Avenue. The plans were adopted after a thorough study by the
engineers of Interborough Rapid Transit Company of all the large power
houses already completed and of the designs of the large power houses
in process of construction in America and abroad. The building is
large, and when fully equipped it will be capable of producing more
power than any electrical plant ever built, and the study of the
designs of other power houses throughout the world was pursued with
the principal object of reducing to a minimum the possibility of
interruption of service in a plant producing the great power required.

The type of power house adopted provides for a single row of large
engines and electric generators, contained within an operating room
placed beside a boiler house, with a capacity of producing,
approximately, not less than 100,000 horse power when the machinery is
being operated at normal rating.

[Sidenote: _Location
and General
Plan of
Power House_]

The work of preparing the detailed plans of the power house structure
was, in the main, completed early in 1902, and resulted in the present
plan, which may briefly be described as follows: The structure is
divided into two main parts--an operating room and a boiler house,
with a partition wall between the two sections. The face of the
structure on Eleventh Avenue is 200 feet wide, of which width the
boiler house takes 83 feet and the operating section 117 feet. The
operating room occupies the northerly side of the structure and the
boiler house the southerly side. The des