FAST AND HEAVY RAILWAY SERVICE. 247
are competent to do the work, but to facilitate distribution
and keep down the working current, alternating motors are
desirable, monophase preferred if practicable. With
polyphase motors the work is not now difficult. The syn-
chronous motor with special means for starting is the neat-
est if stops are very few, but for the high rotative speed
required it 1s not difficult to design induction motors with
both high power factor and great efficiency, amply capable
of doing the work and doing it well. Probably such motors
offer on the whole the best available means for attaining
the end in view. Four motors of 150 nominal horse power
each, capable of working up to 250 h. p. without much drop
in speed would be fully equal to the work, and such motors
can be readily produceéd at any time, as the size is nothing
unusual, and the conditions quite easy tomeet. The work-
ing voltage should, of course, be kept high; 2500 volts is
entirely practical, and this pressure would keep the cur-
rent through the trolley contacts down to limits already
passed in present practice. It is at least an open question
whether under the conditions which would be found on a
high speed road of this kind it would not be feasible and
advisable to use the whole voltage of transmission—10,000
volts or more—on the trolley wire and carry the trans-
formers upon the locomotive. A bare wire would be used
for the transmission in any event and there is no conclu-
sive reason why it should not be carried over the track.
Otherwise a large number of large transformers, aggregat-
ing several times the capacity of the motors, would have to
be distributed along the line. Unless the service is very,
heavy this is needlessly expensive and increases the items of
labor and depreciation.
Of course, it might be aesirable to use two motors in-
stead of four and to vary the arrangement of parts in many
ways, but such details have no place here, where merely
the general scheme is under discussion.
The problem of effective braking is a serious one, but
not so serious as at first appears. A well protected clear
right of way with no grade crossings is absolutely necessary
