Scientific American Supplement, No. 711 | Page 8

upon some recent
electrical work on the elevated railroads and its bearing on the rapid
transit problem. The Railroad Gazette gives the following abstract:

He introduced the subject with a tribute to the efficiency of the elevated
railroad system as it is now operated by steam, with special reference to
that section of it known as the Ninth Avenue line, upon which his
experiments with the electric motor have been conducted, over which
passengers are now conveyed a distance of five miles in 26 minutes for
five cents, which he considered the best and cheapest municipal rapid
transit in the world, and which is operated with a higher degree of
safety than any other railroad in the world making an equal number of
stops per 100 miles. On a recent holiday, April 30 last, 835,720
passengers were carried upon the entire system without noticeable
detention or accident. The rapidly increasing traffic 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 7½
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 that the mean speed with a three-car train running express
on the up-town track was about 24 miles per hour, although the ability
of the motor on a level with a similar train was nearly 28 miles per hour.
This, however, was not the maximum speed, as the level track was not
long enough to permit of its attaining the highest rate. It was the
opinion of the speaker, however, that the speed attained could not be
exceeded with prudence on the elevated structure.
The measurements of speed were made by dividing the track into 19
sections of 500 ft., each section being provided with a circuit-closing
plate connected with a chronograph which was carefully tested. The
indicator cards were taken at the central station by Mr. Idell and his
assistants, and the dynamometer used was of the liquid type made by
Mr. Shaw, of Philadelphia. The diagrams prepared from the data
obtained were then explained by the speaker, who stated that there was
not a marked difference between the 10 ton motor and the 18 ton
locomotive in the initial effort on the level, as will be seen by
comparing a run observed by a railroad officer on March 9 with a steam
motor and a load of about 57½ tons. The steam motor required 1 min.
and 29 sec. to make the distance from 14th to 23d streets, while the
electric motor with a train of 70 tons made the same trip in