Scientific American Supplement, No. 711 | Page 9

1 min. and
50 sec.; the absence of power brakes compelled the current to be taken
off at 19th street, while it was probable that the throttle of the steam
locomotive was not closed until it reached 23d street, this being the
usual practice. The data obtained in these experiments shows that
29,940 h.p. is required to operate the Ninth avenue railroad for the 16
hours' service, or an average of 1,871 h.p. per hour, or 2,181 h.p.,
adding station friction. The varying requirements of the traffic during
the day shows that the service could be advantageously divided up

between four stationary engines of 800 h.p. each, there being but five
hours of the day when all of them would be required. The fuel
consumption per day, allowing 22 lb. of coal per h.p. per hour at $2.25
per ton, would make a total of $92.25 per diem for fuel, the coal being
a mixture deliverable at the dock for about $1.80 per ton. The weight of
coal used for the present locomotives is about the same, viz., 40 tons
per day, but practice has shown it to be most economical to use coal of
the best quality, costing $5 per ton, making the cost of fuel about
double that required for the electric system. Without entering into other
economies which the speaker claimed were in favor of electricity, and
ignoring the plan suggested by Sir William Siemens of braking the
train by converting the motor into a dynamo and thus utilizing the
energy of momentum, he believed that the economy in fuel alone was
sufficient to prove that the application of power by electricity was
preferable to direct steam propulsion for the elevated railroad service.
* * * * *

MAGNETISM IN ITS RELATION TO INDUCED
ELECTROMOTIVE FORCE AND CURRENT.[1]
[Footnote 1: A paper read before the American Institute of Electrical
Engineers, New York, May 22, 1889.]
By ELIHU THOMSON.
There is perhaps no subject which at the present time can have a greater
interest to the physicist, the electrician, and the electrical engineer than
the one which heads this paper. The advances which have been made in
the study from its purely theoretical or scientific side, and the great
technical progress in the utilization of the known facts and principles
concerning magnetic inductions, can but deepen and strengthen that
interest.
On the side of pure theory we find the eager collection of experimental
data to be submitted to the scrutiny of the ablest and brightest minds, to

be examined and reasoned upon with the hope of finding some clew to
satisfying explanations, and on the side of practice we find the search
for new facts and relations no less diligent, though often stimulated by
practical problems presented for solution. Indeed, the urgency for
results is often the greater on the practical side, for theory can wait,
practice cannot, at least in the United States.
We must look for continued triumphs in both directions, and the most
welcome of all will be the framing of a theory or explanation which
will enable us to interpret magnetic and electric phenomena. The recent
beautiful experiments of Hertz on magnetic waves have opened a fertile
region for investigation.
It would seem that the study of magnetism and electricity will give us
the ability to investigate the ether of space, which medium has been
theorized upon at great length, with the result of leaving it very much
where it was before, a mysterious necessity.
Faraday says, speaking of magnetism:
"Such an action may be a function of the ether, for it is not at all
unlikely that if there be an ether it should have other uses than simply
the conveyance of radiations." 3,075. Vol. III., Exp. Res.
"It may be a vibration of the hypothetical ether, or a state of tension of
that ether equivalent to either a dynamic or a static condition," etc.
3,263. Vol. III., Exp. Res.
Faraday again says, speaking of the magnetic power of a vacuum:
"What that surrounding magnetic medium deprived of all material
substance may be I cannot tell, perhaps the ether." 3,277. Vol. III., Exp.
Res.
Modern views would seem to point that through a study of magnetic
phenomena we may take a feeble hold upon the universal ether.
Magnetism is an action or condition of that medium, and it may be that
electrical actions are the expression of molecular disturbances brought

about by ether strains or interferences. The close relations which are
shown to exist between magnetism and light tend to strengthen such
views. Indeed, it would not be too much to expect that if the mechanics
of the ether are ever worked out, we should find the relation between
sensible heat and electric currents to be as close as that of light to
magnetism, perhaps