The mirror., 1919-04-24
Y paper deals with the
physics of light, or
more : properly. with

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IX@M|WkH more properly, with
SGB certain peculiarities or
manifestations caused by the ac-
ton of light. 1t is my purpose to
explain, as we'll as my ability and
the time allowed me will permit,
several of the phenomena of light,
such as the velocity of light. re.
flection, refraction, mirage, the
solar spectrum, and the rainbow.
But in order to understand the
cause of these phenomena, it is
necessary for us to understand the
exact nature of the physical energy
known as light, and some of the
immutable laws which govern its
actions. For this purpose l have
prepared an explanatory preface,
explaining the physical compost
ton of light, which follows:
Light has it's origin in radiant
or luminous body. So if we heat
body until it becomes radiant or
luminous, it then emits a form of
physical energy. This energy or
emanation travels through space in
the form of vibrations or waves,
and these waves are known as light
waves. Space is known as ether
and is infinite. We do not know
just what ether is. But we do
know that it occupies all space and
is present in all substances, no
matter how dense. 1t is a rare,
transparent, elastic medium. For
lack of a better simile we may
compare ether to water. If we
drop stone into a pool of still
water it will cause circular waves
which travel equally in all direc-
tions. Yet, strictly speaking. the
waves do not travel. They merely
undulate. So does radiant body
cause circular waves in the ether.
Each wave front is made up of
countless rays, and these light rays
travel in straight lines. On meet
ing the surface of another medium
several changes may occur in their
course. They may then be reflected
absorbed, refracted, etc. We will
deal with these changes later.
We are at liberty to distinguish
between the terms Eight waves
and Eight" As before stated,
light waves are the emanations OF
a luminous body. When these
emanations strike the eye they
cause the sensation of light. In 9
general sense the words light
and sight may be used synony.
mously, since it is true that a man
without sight is a man without
light. Yet there are exceptions to
this rule, for there are light waves
which do not affect our organs OF
vision, These invisible light
waves will be dealt with in our de.
scription of the solar spectrum. Il
we differentiate between light
waves and light and use the worc
light as applying to a sensation
only. then we must admit tina,
light cannot be considered as 9
concrete or tangible substance. A
sensation cannot have materia
form. In this respect light is SINH
lar to sound, since sound likewise
is but sensation. As generally
used, however, the word light in
cludes both the emanations of .
luminous body and the sensation
caused by the striking against tn,
eye of these emanations.
Light travels through space a.
the rate of 10000 miles per sec
ond approximately. We accep
the word of the scientific investi
gator for this fact. yet we may
readily determine the velocity o1
light ourselves. No complicated
instruments are necessary and the
process is quite simple. All thai
is required is a small telescope. ar
astronomical almanac and watch
(This is the original method BY