Sharp County record., 1891-04-09
THE FLIGHT OF LIGHT.
Speed That Is Too Great for the Human
Brain to Fully Comprehend.

Braln TO ully tOnlpfenchu'
If you could take all the people in the
world and set them out in space mile
apart, like mile posts along a railroad,
and then at the further end use all the
dogs and cats to extend the line Of mile
posts, you would run far short of ma
terial to mark the distance out to the
earth's brother planet, Neptune Again.
if you could use all this material OF
men, women, children, dogs and cats
and put them out so that they would be
as far from one another as Boston Is
from San Francisco, your line wouldnt t
be half long enough to reach to the
nearest star.
On clear night the average eye will
see stars as low as the sixth magnitude
Such shining beauty as Sirius winks
at you so archly that it seems almost
impossible that years are consumed In
the passage of its rays to the earth,
when we remember that light travels
more than one hundred and eighty
thousand miles in a second. Yes, if the
nearest of the beautiful twinklers should
be blotted out and at this moment we
should still see it without the slightest
change in appearance two or three
years after Chicago cleans up the debris
of the worlds fair.
But even a star as far away as that
seems nearly within touching distance
when we find that other stars visible
with the telescope, are so far away that,
for all we know, they may have been
blotted out before Cain and Abel were
born. That is to say, if one of those far
distant orbs had been utterly annihi-
lated, as you would snuff a candle,
when Adam and Eve were enjoying
themselves in the Garden of Eden the
rays then starting toward the earth,
Notwithstanding the awful speed of
light, could not get here in time to
meet the closing of the nineteenth CEN
tury.
How do we know that light travels at
such wonderful speed? Upto about two
hundred and twenty-five years ago it
was supposed that rays of lightfrom all
the celestial orbs passed instantly to the
observers eye. The old astronomers in
fact, never took thought to the matter
at all. They simply saw the sun and
the stars, but they never dreamed that
the rays from them had to journey
millions, billions and trillions of miles
in getting to mundane eyes. 1t was the
great fortune of a Danish astronomer to
make the great discovery that light as
well as sound or railway train re-
quires a given time to travel a given
distance.
Roemer, the famous Dane, alluded to,
was led to his discovery by observations
of the eclipses of Jupiter's moons He
found that there was difference Of sew
erar minutes in these eclipses, that they
occurred earlier when the earth was on
the side of the sun nearest to Jupiter
and later when farthest away. With
this data as a starting point he soon
found that the difference of apparent
time resulted from the time required
for light to travel across the diameter
of the earth's orbit about one hundred
and eighty-two millions miles. This
time proved to be about sixteen min
utes, and as half that would be the
time from the earth to the sun the mys-
terry was solved.
The accuracy Of this calculation has
since been verified by other methods
and all authorities now agree that the
velocity of light is not far from 1856 900
miles a second. 1t is difficult for the
mind to grasp and comprehend such
speed. The swiftest animated thing is
undoubtedly the pigeon, which has been
known to travel hundreds of miles at
the rate of fifty miles an hour. A little
arithmetical exercises will show that it
would take a pigeon more than two
hundred years to cover the dis
tance to the sun at fifty miles an
hour without stop; and to go as far as
Neptune it would take q bird nearly q
thousand years,
When we want to see an illustration
Of speed we often use the expression
swift as n cannon ball But If you
could fire u cannon ball to the sur
when you are college freshman, youl
hair would be sprinkled with gray wher
the ball stopped for you would be
seventeen years older than when you
Gred the shot. Philadelphia Times,