1528.3 meters; the gauge was 1 meter, and 60 per cent. of the length
consisted of tangents, the remaining 40 per cent. being mostly curves
of 250 meters radius. The gradients, three in number, were very small,
averaging about 1:750.

Two generating dynamos were used, which were coupled in parallel
circuit, but in such a manner that the difference of potential in both
machines remained the same at all times. This was accomplished by the
well known method of coupling introduced by Siemens and Halske, in which
the current of one machine excites the field of the other.

Although the railroad was not built with a view of obtaining a high
efficiency, an electro-motive force of only 150 volts being used, a
mechanical efficiency of 50 per cent. was nevertheless obtained, both
with one generator and one car with thirty passengers, as well as with
two generators and two cars with sixty passengers; while with two
generators and three cars (two of them having motors) the same result
was shown.

[Illustration: THE ELECTRIC RAILWAY AT VIENNA.]

The curves obtained by the apparatus that recorded the current showed
very plainly the action within the machines when the cars were started
or set in motion; at first, the current rose rapidly to a very high
figure, and then declined gradually to a fixed point, which corresponded
to the regular rate of speed. The tractive power, therefore, increases
rapidly to a value far exceeding the frictional resistances, but this
surplus energy serves to increase the velocity, and disappears as soon
as a uniform velocity is reached.