[Illustration: RINGING AND CHARGING MACHINES AND POWER BOARD Plaza
Office, New York Telephone Co.]

_Strength of Building._ The major portion of telephone central-office
apparatus, whether automatic or manual, is not of such weight as to
demand excessive strength in the floors and walls of buildings.
Exceptions to this may be found in the storage battery, in the power
machinery, especially where subject to vibration, and in certain cases
in the cable runs. After the ultimate size of the equipment has been
determined, the engineer and the architect should confer on this point,
particularly with reference to the heavier portions of the apparatus,
to make sure that adequate strength is provided. The approximate weights
of all parts of central-office equipments may readily be ascertained
from the manufacturers.

_Provision for Employes._ In manual offices particularly it has been
found to be not only humane, but economical to provide adequate quarters
for the employes, both in the operating rooms and places where they
actually perform their work, and in the places where they may assemble
for recreation and rest. The work of the telephone operator,
particularly in large cities, is of such a nature as often to demand
frequent periods of rest. This is true not only on account of the
nervous strain on the operator, but also on account of the necessity,
brought about by the demands of economy, for varying the number of
operators in accordance with the traffic load. These features accentuate
the demand for proper rooms where recreation, rest, and nourishment may
be had.

_Provision for Cable Runways._ In very small offices no special
structural provision need be made in the design of the building itself
for the entrance of the outside cables, and for the disposal of the
cables and wires leading between various portions of the apparatus. For
large offices, however, this must necessarily enter as an important
feature in the structure of the building itself. It is important that
the cables be arranged systematically and in such a way that they will
be protected against injury and at the same time be accessible either
for repairs or replacement, or for the addition of new cables to provide
for growth. Disorderly arrangement of the wires or cables results in
disorder indeed, with increased maintenance cost, uneconomical use of
space, inaccessibility, liability to injury, and general unsightliness.

The carrying of cables from