Ottumwa semi-weekly courier. [volume] (Ottumwa, Iowa) 1899-1903, 1903-06-09
THREE NOT
ABLE DEVICES
Peter Cooper Hewitt of New York City
the Inventor.

Peter Cooper Hewitt, of New York
City, is the inventor of three electri-
cal devices which are destined to
play important parts in the electrical
progress of the world. They are his
mercury-yapor lamp, his static con-
verter, and his current interrupter.
Each is based on the principles of the
passing of an electric current through
the yapor OF mercury contained in a
partial vacuum. The mercury-vapor
lamp was the first production of the
inventor along this line.
1t was an April 70, 1901, that Coop
er Hewitt first exhibited the lamp,
and its development has gone on since
that time until now it is a commercial
article. AS usually constructed it
consists of long glass tube about an
inch in diameter. A little mercury is
placed in an expansion of the tube at
its lower end. The electric wire ter
minals or electrodes, are passed into
She tube, one at each end; the air is
partly exhausted and the tube sealed.
The lamp operates on ordinary Ito or
115-yolt direct-current circuits, such
as are commonly used for incandes-
Gent lighting. AS it will not start on
such a circuit an induction coil is pro-
Sided for producing temporary high
voltage current. This vaporizes a
part of the mercury at once, and the
whole tube becomes filled with a pow
erful light of a pale green tint. The
path for the ordinary circuit is thus
! opened. and the luminosity of the
tube is maintained. The light is quite
steady and very economical, there be-
ing no glowing solid to wear out or
be consumed, as in the case of mean
descent or arc lamps. A popularity
of the light of this invention lies in
the fact that it contains no red rays.
4 Practically all of the other colors OF
! the true spectrum are there, from
Sorange yellow to violet, but the abb
Esence of the pure red rays has ten
3dency to make so called red objects,
kwhen viewed under the light, appear
Hpurplish or black. A persons com
tpleXion under the mercury-vapor light
dis given peculiarly CHASTITY effect, as
Sred and flesh tints appear blush pur
6ple and White tints become gray. The
&fact that all colors except red appear
agreatly heightened when viewed un
oder the mercury-vapor light is to be
wturned to advantage at the Louisiana
4Purchase exposition at st. Louis, where
pthe light. is to be used for decorative
Mand spectacular purposes.
n The mercury-vapor lamp has many
Disadvantages. The light has an eft
Efficiency at least eight times as grea
Vas that obtained from the ordinary in
W,andescent lamp. AS the vapor laml
5lase large luminous area, it produces
Sac, sharp shadows. While the lack o
sred in its spectrum is Objectionable TO
Nsome purposes, in many way it is ;
positive advantage. For reading
Sdraughting, shop and other work il
(which the eye undergoes continuous
nstrain, the absence of red rays is al
advantage. That one can read ant
Mwrite for longer periods and with les
Matigue under this lamp than by tn
Night of any other is said to have beel
Nproved by experience. The lamp
Msuitable also for large spaces in whicl
@goods are handled. for the lighting 0
Etunnels and factories, and for ordinar
street lighting. For purposes in whic
1.-THE absence of red rays would be oil
kjectionable, some of the yellow ray
tmignI be transformed into red, Or tn
light may be mixed with that from tn
ordinary incandescent lamps. 1t ha
sheen| noticed also that the mercur,
ivapor light has very great penetrativ
power, being effective throug
greater distances than the common il
Candescent lamp of equivalent candle
power.
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