Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1922-06-22

The universe is full Of sending and
rsceiying Instruments. each with Its
own range OF wave lengths. You
pluck q string and you create
waves that can be heard by the ear.
pnt your hand near u fire and the
nerves respond TO the wave lengths
which cause heat. Light Is the
result Of certain wave lengths
which the eye can see. There are
wave lengths longer and shorter
than this, but the eye does not
respond to them
The reader who is following these les.
sons in radio may feel that / am over
emphasizing the Importance of study
ine the subject of vibrations and the
matter Of wave length. but we are
living IN n universe whose very exist
snce depcnds upon vibrations, and oil
NJ the joys and all of the sorrows OF
the world might almost be said to mar.
row themselves down to a question OF
The wave length of these vibrations.
You wake up on one Of these beauti-
ful summer mornings and see a glorious
day of sunshine and you arc happy.
why; Scientifically il is because of
thc vibrations of the particular wave
lengths which are having their effect
upon you.
With no clouds to interfere there are
vibrations with wave lengths OF from
one thirty -thOusandth to one sixty
thousandth of an inch. and that Is pure
sunlight--the combination of all Of the
wave lengths within that range. The
frequency of these vibrations runs up
TO trillions Of times a second. but you
do not stop to count them; you merely
know that your eyes receive, the glowing
sunshine.
That is because the nerves Of your
eve have tuned themselves to respond to
these vibrations.
You turn your eyes away from the
heavens and look across the country and
YOU sec green fields and the color of
the lush brown earth freshly upturned
by the plow. or n flash Of rcd or blue
or yellow from some bird dashing in and
out among the trees or any one of the
myriad colors of the flowers.
You do not have to turn any knobs
or test any currents or twist any
variomcters to get the full effect of all
this beauty. And yet. as your eye
passes from one color to another. nature
herself takes care Of all this tuning for
lengths without being conscious of 1t.
Some day. perhaps, you will be able
to work your radio receiver just as
quickly anu as surely. But the two
processes are fundamentally the same :;
light, whether the white light of the
sun or the different colors that you see,
Ia entirely matter Of wave length.
You will see in the advertisements
Of radio receiving sets such qualifying
statements as "wave length range $50
to I50 meters" You may wonder why
It is necessary to have limits of this
kind placed upon set.
Remember that. in this vibrating uni
verse in which we live. there arc waves
so long that they will reach score
of miles from one crest to the other.
and there are waves so short that the
only way that we can measure them is
to put them against the shortest wave
we actually can measure and calculate
how often these waves interfere with
each other. 1t is not too much to say
We could have billion of them on the
head Of pin.
1t is beyond possibility for any one
piece of mechanism to respond to such Il
lmitlcss range. The eye responds to
waves between one thirty -thousandth
and one sixty -thousandth of an inch
from crest to crest, and these waves,
producing what we call light, give the
marvellous gift of sight.
There are waves still smaller than
these visible ones. We know that
they exist because we can make pictures
with them upon an ordinary photo
graphic plate even though the eye can
not 500 them. They are what they call
the ultra violet rays.
As we got to the longest waves that
can be seen. producing the sensation
which we know as the color red we
begin 10 be conscious of them through
another of our senses, and this is the
sense Of touch. The vibrations cause
what we know as heat.
Thus the human body has separate
receiving SGT for tuning in these waves
OF different lengths.
The sensation which We call sound IS
also entirely a matter of wave length
bur there is this important distinction
between sound and light: sound waves
are produced by vibrations in the air,
and will not go through vacuum.
whereas light waves are produced in