ut into effect with
varying success, for doubling and quadrupling the capacity of multiple
switchboards, one of these being the so-called divided multiple board
devised by the late Milo G. Kellogg, and once used in Cleveland, Ohio,
and St. Louis, Missouri. Each of these boards had an ultimate capacity
of 24,000 lines, and each has been replaced by a "straight" multiple
board of smaller capacity. In general, the present practice in America
does not sanction the building of multiple boards of more than about
10,000 lines capacity, and as an example of this it may be cited that
the largest standard section manufactured for the Bell companies has an
ultimate capacity of 9,600 lines.

European engineers have shown a tendency towards the opposite practice,
and an example of the extreme in this case is the multiple switchboard
manufactured by the Ericsson Company, and installed in Stockholm, in
which the jacks have been reduced to such small dimensions as to permit
an ultimate capacity of 60,000 lines.

The reasons governing the decision of American engineers in
establishing the practice of employing no multiple switchboards of
greater capacity than about 10,000 lines, briefly outlined, are as
follows: The building of switchboards with larger capacity, while
perfectly possible, makes necessary either a very small jack or some
added complexity, such as that of the divided multiple switchboard,
either of which is considered objectionable. Extremely small jacks and
large multiples introduce difficulties as to the durability of the jacks
and the plugs, and also they tend to slow down the work of operators and
to introduce errors. They also introduce the necessity of a smaller
gauge of wire through the multiple than it has been found desirable to
employ. Considered from the standpoint of expense, it is evident that as
a multiple switchboard increases in number of lines, its size increases
in two dimensions, _i. e._, in length of board and height of section,
and this element of expense, therefore, is a function of the square of
the number of lines.

The matter of insurance, both with respect to the risk as to property
loss and the risk as to breakdown of the service, also points distinctly
in the direction of a plurality of offices rather than one. Both from
the standpoint of risk against fire and other hazards, which might
damage the physical property, and of risk against interruption to
service due to a breakdown of the switchb