Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1892-03-13
Metal Iscisted Under Electric Heat.

Metal 7tcised Under Electric Heat.
made to repair its own defects, with marked
improvement in lasting quality. To a
further experimental refinement the incan-
descent lamp owes another point Of its pres
ent excellence. For lamps success it is
essential that the air be exhausted from its
bulb as thoroughly as possible.
Two Other Important Discoveries
Notwithstanding the use of the best
pump, Mr.. Swan, one of the pioneers of elec-
trio lighting, detected that his 6laments
were attacked by oxygen. It occurred to
bon itself, for he well knew how strong was
the affinity between gases and porous forms
Of carbon Thought he, it may be that If
the fIament were kept aglow during the
pumping operation the oxygen could be dis
lodged. Experiment proved the soundness
of his surmise, and another advance in lamp
making was scored. In leading the wire S
bearing current into lamp inventors en-
countered a good deal of difficulty. This
was overcome on discovery that platinum,
when heated, has much the same rate of ex-
FEASIBILITY as glass An arc light being
five times as brilliant as an incandescent
lamp, in proportion to the current supplied,
there is widespread demand for an arc
illumination. In this branch of invention
German electricians have brought out a
better device than any originated on this
side of the ocean.
The electric light, perfect as it is. would
know no rival were its cost brought within
an easily feasible limit. Let us briefly con-
slider how this may be done, as estimated by
Mr.. John Van Week, one of the foremost
electrical engineers OF New York. His
computations chiefly turn on the immense
economy which attends doing work on a
large instead of small scale. In arriving
at the conclusion that the cost of current
could be reduced to one-fourth or one-ffth
its present figure, he takes account of what
may be saved in production, transmission,
and varied service. Steam engines Of the
marine type, multiple expansion, operated
at pressure of $50 to 800 pounds to the
square inch, could be employed. With
such plant, working in units Of not less
than 1000 or 5000 horse power, the con-
sumption of coal would be half the quantity
usual in central stations
Economy in Transmitting Current
In generating the current, three-phase
dynamos, such as those erected at Lauffen,
in Germany, last summer, could be en-
ployed. Taking a leaf out OF the expert
ence gained in transmitting electricity from
Lauffen to Frankfort, the transformer at the
producing station should lift to pressure
of 10, 600 volts For the safe and economical
transmission ofsuch current to and through
New York. the Ferranti conductor is pro-
posed. This conductor consists of thick,
hollow tube of copper around which is
wrapped 400 to 500 thieknesses of paper i'm
pregnated with ozokerite, one of the best
insulators known. Encircling the paper is
an annular tube of copper which serves a.
the return conductor, and which may, if de-
sired, be safely connected with the ground.
This second tube, covered with more paper
and a stout iron pipe, is laid in a Ab-way
or under water.
The security attending the Ferranti con-
ductor has been abundantly demonstrated.
When, for example, it has been pierced or
divided by an az, the current has passed
from the core to its metallic covering with
out doing the slightest damage. Its efici-
ency is not less remarkable than its safety.
Were stretch of it laid from New York to
Buffalo, it would offer no more resistance
than mile Of the subway conductor now
doing duty in Broadway, New York City.
With feasible improvements, which would
add but one-ffth to its cost, the Ferranti
main could carry current of *, 600 volts
as effectively as it now conveys one Of
10000.
Europe Ahead Of Us In ECONOMY.
Even if the present low pressures of $50
to 1000 volts were to remain unchanged,
there would be decid ed gain In substituting
wholesale for retail methods OF distribu-
tion. To lay wires of ten-f6d capacity
would call for but five times the existing
investment. And with the very diversified
applications of the current an important
saving comes in. As motive power it is in
demand during several hours Of the day
when but few lamps are burning. The
same thing is true of its manifold uses in
electro-deposition. This enables the plant
at the producing station to be employed
much more fully and evenly than would
other wise be the case. And engines and
dynamos, like men, earn most when they
are doing their full stint.
Mr. Van Weeks plans, if given effect,
would probably realize at . bound an ex-
existing lines Of supply would come only at
the end Of lengthy roll of years, if ever.
In taking the steps indicated the electrical
engineers of America would but follow q
line OF development already marked out in
the practice Of their brethren across the
sea, and to some extent already begun here
and there in the United States. In Eng
land and Germany the steam pressures at
central stations are commonly much higher
than the American standard; dynsmos arc
of better design than those in this country;
the voltages employed in transmission are
generally higher, as between Deptford and
distribution . close economy has been
studied with results very desirable here.
Not Yet Availabls for Heating.
But for one limitation electricity would
be adopted not only tor lighting and a.
motive power, but for heating. Generated
ths D 4
engine in converting heat into works levy
noYer leaa than 8S mar can't and ganarn1lv