CONCLUSION 473
unused types of apparatus, since at any time circumstances may
arise which lead to their extensive introduction.
255. With many of these known but unused or little used ap-
paratus, we can see and anticipate the industrial condition which
will make their use economical or even necessary, and so lead to
their general introduction.
Thus, for instance, the induction generator is hardly used at all
today. However, we are only in the beginning of the water-
power development, and thus far have considered only the largest
and most concentrated powers, and for these, as best adapted,
has been developed a certain type of generating station, compris-
ing synchronous generators, with direct-current exciting circuits,
switches, circuit-breakers, transformers and protective devices,
etc., and requiring continuous attendance of expert operating
engineers. This type of generating station is feasible only with
large water powers. As soon, however, as the large water powers
will be developed, the industry will be forced to proceed to the
development of the numerous scattered small powers. That is,
the problem will be, to collect from a large number of small
water powers the power into one large electric system, similar
as now we distribute the power of one large system into numer-
ous small consumption places.
The new condition, of collecting numerous small powers—
from a few kilowatts to a few hundred kilowatts—into one sys-
tem, will require the development of an entirely different type of
generating station: induction generators driven by small and
cheap waterwheels, at low voltage, and permanently connected
through step-up transformers to a collecting line, which is con-
trolled from some central synchronous station. A cheap hy-
draulic development, no regulation of waterwheel speed or gen-
erator voltage, no attendance in the station beyond an occasional
inspection, in short an automatically operating induction gen-
erator station controlled from the central receiving station.
In many cases, we can not anticipate what application an
unused type of apparatus may find, and when its use may be
economically demanded, or we can only in general realize, that
with the increasing use of electric power, and with the intro-
duction of electricity as the general energy supply of modern
civilization, the operating requirements will become more diver-
sified,-and where today one single type of machine suffices—as
the squirrel-cage induction motor—various modifications thereof