Courier Democrat. (Langdon, N.D.) 1891-1920, 1892-05-05
Electric Lamp Making.

Certain interesting steps OF the pro-
cess, are matters OF public informa-
ton. The first carbon filaments made
seldom lasted more than fifty hours,
rendering the cost OF lamp renewal as
much as the cost OF current. In en-
deavoring to prolong the life OF lamp
it was noticed that the flament was
brighter at some points than others,
indicating q variation OF size. Could
this be remedied? Could the filament
be made OF uniform diameter? For
tunately, yes. Several years before,
NJ. Duprez, O French chemist, had re-
corded one of those observations so
common in science, which, barren at
the time they occur, afterward spring
into fruitfulness through disclosing re-
lationship to q puzzling problem.
He noticed that carbon heated in
an atmosphere OF hydro-carbon re-
ccived u deposit OF an extremely
dense form OF carbon upon it's surface.
Here lay the key to increasing the
durability Of the lamp tilament. In
lnersing it while luminous in O. heavy
hydro-carbon gas or liquid, it took
on Il solid Goa ting and where the fla
ment was hottest and therefore thin
nest the deposit became thickest. In
this ingenious fashion the thread was
made to repair its own defects, with
marked Improvement in lasting quail
ity. TO a further eXperimental refine
ment the lncandescent lamp owes
another point OF it's present excellence.
For II lamps success it is essential
that the air be exhausted from it's
bulo as thoroughly as possible.
Notwithstanding the use OF thH best
pump, Mr.. Swan, one OF the pioneers
OF electric lighting, detected that his
tilaments were attacked by oxygen.
It occurred to him. that perhaps a
little OF this gas might have been left
in the substance OF the carbon ITSELF
for he we'll knew how strong was the
affinity between gases and porous
forms OF carbon. Thought he, it may
be that ii the ilament were kept
aglow during the pumping operation
the oxygen could be dislodged. Ex-
pertinent proved the sorndness of his
surmise, and another advance in
lamp making was scored. In leading
the wires bearing d current into q
lamp, inventors encountered a good
deal OF difficulty. This was overcome
on discovery that platinum, when
heated, has much the same rate OF eX-
FEASIBILITY as glass.
CONTINUOUS ALTERNATING CURRENTS.
In producing current for lighting the
choice lies between two plans, that OF
q continuous current, usually OF COM
paratlvely low voltage, or pressure,
and that OF an alternating one, usual
ly, but not necessarily, OF high voltage.
The alternating current, which may
have its polarity reversed 100 to
1000 times Il second, has the advan-
tagc OF lending itself to economical
Transformation that is to the produc-
ton OF changes in its pressure. 1t can
be regulated also with less loss OF en-
ergy than q continuous electrical
stream. The continuous current when
furnished, as it usually is, at $50
volts, is well within the safety limit,
and on the three-wire system supplies
incandescent lamps at l25 volts,
avoiding the toll exacted by even the
best transformer. This is the current
suitable for compact city circuits;
with scattered circle of custom. such
as that OF a suburban district, the al
ternating system is preferred.