The Savannah morning news., 1902-01-26

per inch is produced.
I'm the incandescent lamp the car
bon filament is highly resistant to the
electric current and the passage of the
current heats the filament so that light
is generated. In the new lamp the mer-
curry vapor takes the place of the fla
ment. Its resistance, however, is very
much greater than the resistance of the
carbon and when sufficient current is
passed a much more brilliant light is
produced. 1t was thought TO be inn
possible to use the constant current
because the very resistance of the va
per kept this current from passing
through.
II discovered a peculiar fact. how
ever, and working therefrom solved the
problem. found that the resistance of
the mercury vapor was only, as it were
momentary. That is, the moment any
current at all was passed through the
tube the current itself seemed grad
ually to break down the resistance UNI
til at last the resistance became so
small that even constant or mean
descent current would light the tube.
AT present l use small spark or in
duction coil to open the path imme-
diately for the current. In short if the
current is turned into the tube ordi-
narily it will not light until a spark
from the coil is first driven through to
break down the resistance, to blaze
way SO to speak for the
current. OF course, the whole opera
ton is instaneous."
One of the spark coils was attached
to the lamp on the wall and when Mr..
Hewitt turned on the switch to light
the lamp the swapping of the sparks
could be heard. The intense wilderness
of the light became the subject of
comment. 1t has always been said
that tube lighting would be undesira-
BILE because of the absence of red rays,
Mr.. Hewitt was asked about this. He
replied:
1.-The light produced by pure mer-
curry gas comprises orange-yellow,
lemon green, green, blue, blue violet
and violet: and although all shades
of these colors may not be present,
their absence would not be so seriously
felt were it not for the absence of
the red. For some purposes the lack
of red in the spectrum is Objectionable,
but for many uses it is positive adj
vantage. For shopwork, draughting
reading and other work where the eye
is called on for. continued strain the
absence of. red is an advantage, for
l have found light without the red
much less firing to the eye than with
it. 1t is possible to transform some
low light, into red light, and thus
in measure to overcome this defect
where required for general indoor
illumination. A moderate amount of
ordinary incandescent light inter-
sperSed with the mercury vapor elec-
trically serves to supply the deficiency
and the mixture may be made most
satisfactory.
For street lighting purposes the
mercury light is available even with
out the red and it should be noticed
that this light has very great pene-
tratfng power and seems to be effec-
tive through greater distances than an
equivalent amount of measured candle
power from the ordinary incandescent
lamp. This may be due to the fact
that the waves of the red light are less
penetrating than those waves which
are present in the mercury light and
hence the least valuable portion of the
spectrum having such Illuminating eff
fects is omitted and the energy is prac-
tically expended in the NOSE useful
portions of the spectrum. I have made
| lamps in which this color objection has
been overcome, sacrificing on some oc-
casions the extremely high light eff
| fciency obtained in this particular
lamp. Without doubt lamps of this
type will be produced whose light will
be even more beautiful than this light
| is objectionable. The fact that differ
| ent gases or vapors produce different
| colors opens the way for experimental
ton in this line. l have produced lamps
of various colors. Hydrogen gas gives
large amount of red rays; so does
nitrogen. / have made blue lamps
and yellow. This feature of the color
rays will be improved with time There
is a precedent in the Welsbach lamp
which was very blue when it was first
used and in the Nernst lamp which has
also been improved. Even the Edison
incandescent lamp was defective in its
color quality when first invented"
In the opinions of many scien-
tific men, the invention of
the Hewitt lamp is the greatest
electric-lighting achievement since
the Edison lamp was given
to the world. The cost of running the
new light is now but one-eighth of that
of the Edison lamp, power for power.
II must therefore be more economical
than gas; even as cheap as kerosene.
The darkest parts of cities could be
lighted as well and even more econom-
ically than their main streets. Light
houses will be able to shed their rays
many more miles out to sea than they
do at present. The danger of collision
between steamships will be minimized.
In short there is almost no department
Of public or private life that would not
be benefited by such an illuminant.