affic
makes the demand for better facilities a pressing one, and as
the average half million now carried daily will soon become a
million, it appears doubtful if any method can be devised of
providing for the growth by the use of steam motors on the
present structures, which are now taxed to their utmost. To the
mind of the mechanical engineer, having in view the ordinary
coefficients of tractive ability, there is no remedy for this.
The speaker stated that these coefficients were not entirely
trustworthy. He reiterated his previously expressed opinion,
based on frequent experiments, that there is a decided increase
in traction gained by the passage of the electric current from
the wheels to the rails, giving the details of one test where a
motor with a load making a total of 600 lb. climbed a gradient
of 2,900 ft. per mile, starting from a state of rest. He stated
that some of those people who had ridiculed his statements had
finally admitted that they were true.

The motor Ben Franklin, which had been used in making these
tests on the elevated roads, weighed 10 tons, and performed
service nearly equal to the steam motors weighing 18 tons. The
object of these tests was the determination of coal economy.
Tests with a Prony brake showed that the motor developed 128
H.P. The piece of track on which the experiments were conducted
embraced 2,200 ft. of level track and 1-8/10 miles of gradients,
varying from 11-3/10 to 98-7/10 ft. per mile, while at Thirtieth
street the station is at the foot of the steepest grade, thus
testing to the utmost the tractive capacity of the motor. The
experiments were begun in October, 1888, and carried on between
the hours of 9 P.M. and 4 A.M., beginning with one or two cars,
the load being increased nightly until it was finally made up of
eight coaches of 12 tons each, which were hauled up the 98 ft.
grade at a speed of 71/2 miles per hour, the entire distance being
covered at the rate of 14-6/10 miles per hour. The maximum speed
obtained on level with that train was 16.36 miles per hour.
Seventy trips were subsequently made with a 70 ton train
operated between the steam trains under 3 minutes headway, but
the work was considered too critical on account of the absence
of suitable brakes. A number of experiments made about this time
showed tha