Tulsa daily world. [volume] (Tulsa, Indian Territory [Okla.]) 1905-1919, 1917-04-01

some lamps only about one half the
necessary adjustment Is provided, and
satisfactory results can be had only
with a given type and size Of bulb.
But the owner merely buys bulb
which Is the correct voltage and VIII
tit, hense he gets results as varied as
the bulbs he buys. The types OF ad-
justing devices were criticised, and
necessarily so. because unfortunately
they are most frequently detective.
Bmlb Adjusting TYPE Undesirable.
Mr.. McMurtry remarked that the
bulb adjusting type is undesirable be-
cause If sufficiently stuff to retain po-
sition there IS a tendency for Vibra-
ton to loosen the bulb from It's base.
This is true particularly of those de-
vices In which the adjustment is OBJ
tanned by rotating the bulb II ~ not
unusual In the use OF this type for the
bulb to break the course of ADJUST
mcut Another defect OF the socket
adjusting device is that lost motion
permits displacement of the slight
source radially j. e. out of the re-
flector axis. \ very small displace-
meut viii dIstort the beam TO a con
siderable extent and cause a very dis
trcssng light distribution.
Bulb manufacturers, unaware evil
IDENTIFY OF the actual results obtained
with types which are wholly unsatis-
factory, and users persist in buying
any type of bulb so long as it is of
the correct voltage The error made
by both was brought home torCetully.
In some bulbs the filament is not in
the center of the globe. as 1t should
be but behind 1t. resulting in "A black
spot In the center OF the image. and
with the majority of rays useless he
cause of the wide angle of projection
carrying them upward and to the side.
Automobile hcadlamps are not
properly aimed ana the difficulty can
not be overc me by changing the
bulbs. In the majority OF lamps little
light strikes the roadway sometimes
because the lamps are aligned with
the front of the radiator for the sake
Of appearance. II the projected light
Is kept below 42-inch limit more
road illumination will be had, and
with considerably less glare.
IInmpcrcd by Price Limit.
MIR. McMurtry said: so long as
manufacturers are called upon TO fur
nish two hcadlamps and one taillamp
at a price of less than 50 "A set, we
cannot expect product that VIII
give more than a partial control of
the projected light"
In discussing the problem of glare it
was stated that the intrinsic bill
lianCy and candlepower of the source
are only two factors, and that "A most
important one. the Illumination of
the surroundings. too often is disre-
earded. The suggestion is made that
all tests or comparisons lie made with
the headlamps In an cnv.ronment OF
total darkness and tina tests be stand
ardized otherwise. The following
method of testing was suggested:
The cars to be used should be op-
Grated under identically the same
conditions OF bulb, voltage. candle
power and focal positions. The cars
should be made to pass each other on
an absolutely dark road at various
speeds, and the contrast between the
| road illumination of one car and the
glare from the lamps of the other
should he the means of determining
the efficiency of the method cm-
ployed. The speed should be cons,d
cred, as 1t is of vast Importance.
Various methods now in use for
eliminating glare by dimming the
| light. changing its color and diffusing
| the light were taken up, and ii was
stated that the effectiveness of the
diffusion method. such as by using
frosted bulbs, frosted glass fronts,
screens or so-called diffusing lenses,
depends upon the CandlepOwcr OF the
light source and the area over which
the light is diffused Any variation
in the current passing thru the fila
ment changes the effectiveness of this
method. A screen or so-called lens
used in n lamp with a 20-candlepower
bulb may absorb enough light to re-
duce the glaring effect sufficiently,
but should the owner substitute a bulb
of higher candlepower the lamp at
once becomes glaring altho the owner
may have a certificate emitting him
To protection from police Interference.
The simplest and cheapest method
of glare reduction is in fitting the
hcadlamps but this is not possible on
some cars. especially those in which
the lamps are attached to the radiator
shell Mr.. McMurtry gave his approval
of deflector devices He said:
THE rodiroction of the light by The
use Of prismatic lens fronts not only
keeps the light within the zone where
glare Is not Objectionable, but also
distributes 1t over greater width Of
road II Is an advantage therefore 10
use a device OF this character ire
specuNe OF the existence of glare reg
ulatiCns"
In concluding. it was stated that
satisfactory results can be obtained
with modified reflectors - Dallas
News.