adapting electrical
conditions to the larger cities. The overhead trolley had by that time
begun its victorious career, but there was intense hostility displayed
toward it in many places because of the inevitable increase in the
number of overhead wires, which, carrying, as they did, a current of
high voltage and large quantity, were regarded as a menace to life and
property. Edison has always manifested a strong objection to overhead
wires in cities, and urged placing them underground; and the outcry
against the overhead "deadly" trolley met with his instant sympathy.
His study of the problem brought him to the development of the modern
"substation," although the twists that later evolutions have given the
idea have left it scarcely recognizable.

[Footnote 15: See 61 Fed. Rep. 655.]

Mr. Villard, as President of the Edison General Electric Company,
requested Mr. Edison, as electrician of the company, to devise a
street-railway system which should be applicable to the largest cities
where the use of the trolley would not be permitted, where the slot
conduit system would not be used, and where, in general, the details of
construction should be reduced to the simplest form. The limits imposed
practically were such as to require that the system should not cost more
than a cable road to install. Edison reverted to his ingenious lighting
plan of years earlier, and thus settled on a method by which
current should be conveyed from the power plant at high potential to
motor-generators placed below the ground in close proximity to the
rails. These substations would convert the current received at a
pressure of, say, one thousand volts to one of twenty volts available
between rail and rail, with a corresponding increase in the volume of
the current. With the utilization of heavy currents at low voltage it
became necessary, of course, to devise apparatus which should be able to
pick up with absolute certainty one thousand amperes of current at
this pressure through two inches of mud, if necessary. With his wonted
activity and fertility Edison set about devising such a contact, and
experimented with metal wheels under all conditions of speed and track
conditions. It was several months before he could convey one hundred
amperes by means of such contacts, but he worked out at last a
satisfactory device which was equal to the task. The next point was
to secure a joint between contiguous rails such as would permit of
the passa