Omaha daily bee., 1889-05-05


Various theories have been advanced
to account for the recent subway explo-
sions in New York, says the Electrical
World. 1t is admitted that the subway
contained an explosive mixture Of
gases, but inasmuch as there were no
workmen in the manholes where the
trouble occurred and the covers were
properly fastened down. the origin of
the spark which ignited the gases is in
volved in mystery. The theory of
spontaneous combustion does not receive
much support from those who have for
some time past been conducting a
chemical analysis of the gases found in
the subways, and naturally the blame
is attached to the electric light cables
which were laid In the ducts which ex-
ploded. The statement of the subway
commissioners, however, to the effect
that there was no current in these
cables, obliges us to look elsewhere for
the cause of the trouble.
1t is maintained by some that a cur
rent might have been induced in the
iron ducts by underground electric
light wires in the neighborhood, which
under proper conditions, might produce
spark. A much more probable expla-
nation is, that there may have been a
leak to earth on one OF the adjacent
,11lectric light circuits, which found its
way into the manholes through the iron
ducts and lead-covered cables.
Considerable weight is attached to
this hypothesis by those who have seen
the havoc which is sometimes worked
in telephone exchanges by leakage cur
rents from dynamo circuits being taken
up by telephone lines connected with
the earth. An instance is related where
the entire business of an exchange was
interrupted until the ground was re-
moved from the dynamo circuit. 1t Is
even stated that the entire telephone
business of city could be paralyzed by
any evil-dispOsed person who was will
ing to erect a dynamo IN some out-of-
the-way cellar and properly connect it
with the earth.
1t is not altogether necessary to look
to obscure electrical phenomena for the
unfortunate spark. 1t could be caused
by the jarriug or friction of the top
manhOle cover caused by the passage of
heavy vehicles. Too much time, how
ever, should not be spent in looking for
the origin of the spark, but prompt ac-
tion should be taken to eXpel the dan
gerous gases by comprehensive sys-
tenn Of subway ventilation.
The Dynamo.
The dynamo. stripped of its technical
details, Is machine for Transforming
energy. 1t converts mechanical power
into that phase or manifestation of en-
ergy which we call electricity. Me-
chanical power is cheap and the dynamo
made electricity cheap. The moment
electricity was reduced in cost, the cleo
tric motor assumed a commercial value,
SAYS writer in the Century 1t ceased
to be mere laboratory apparatus ~
became practical machine for con vert
ing electrical energy back into mechan-
ical power. 1t is not easy To compre-
hend the immense Importance OF
this latest evolution OF machines
aud all that it means when we say that
we have now joined the steam engine,
the dynamo ard the motor in one. 1t is
as great an improvement as the inven-
tion OF the steam engine itself. 1t is
not necessary here to enter into the
study OF the electric motor as machine.
The point to consider is the position OF
the electric motor AS a transformer OF
energy and its place in the arts, business,
transportation and manufactures.
CHARGED With Electricity
Some peculiar electrical phenomena
were witnessed at Ocaia, Fia., the past
few days. The building occupied by
Benjamin e. Fox and julius Israel have