White Pine news weekly mining review. [volume] (East Ely, Nev.) 1910-1920, 1911-10-08
GAN YOU GUESS
ON THE WHEELS?
AFTER READING THIS EXPLANA.
TION, TELL 1T To THE NOV
ING PICTURE MEN AND RE.
CEIyE THE REWARD.


People who attend moving picture
shows have noticed that the wheels
of rapidly going carriages, autos, We
hicles of any kind. in fact, go back
ward instead of forward. One of the
technical magazines devoted to the
and science, has undertaken to ex-
plain this strange phenomenon. To
the writer of the article the situation
is doubtless as clear as the waters of
the purling brook; to the ordinary
reader 1t is clear as mud. The writer
says that Edison can't explain, but
that he can; and proceeds to do so.
Anybody finding the right answer
can take it to any of the moving pic
ture shows and get the reward. Here
is how the writer proceeds with his
procession:
Carriage wheels, fly-wheels, in fact
any wheels with spokes in them,
when seen in motion pictures, all APP
pear to be turning backwards, or
standing still. If they do by any
chance turn occasionally the right
direction, it is seldom or never at the
proper speed. The effect is rather
curious, and constitutes the greatest
optical defect of the motion picture.
Only a few days ago a group of ex-
hibitors asked a well known producer
to explain the phenomenon. The
producer replied that he could not
explain it, because Edison himself
could not; that it was merely an
optical illusion.
e was right about it being an illus
ion; but he was decidedly wrong
about its inexplicability. The ex-
PLANTATION is simple enough.
Next time you are near a high
board fence with good sized cracks
between the boards, wait for a car
riage to drive past the other side Of
the fence. Then If you look at the
fence you will get the same effect
the carriage weels will appear to
stand still or turn backwards. Per-
haps that will help you to reason it
out.
A motion picture film, as you well
know, is made up of a large number
of small pictures, each practically in
Simultaneous in it's taking. Now if
you take a film with a moving carri-
age shown n 1t, and examine a single
one of the pictures, the carriage will
appear to have been standing still;
you can see all the spokes in the
wheel.
Now suppose the spokes in the
wheel are just five inches apart. And
suppose the carriage is rolling along
at a speed that carries it forward
just five inches beween one picture
and the next. The spokes then in
the second picture will look just the
same as they did in the first, and the
wheel will be seen not as they turn
ed at all. On the screen only per
~sistence of vision" makes you seem
to see a continuous moving picture;
you really see only a succession of
single, %instaneous pictures. So when
you projected the picture we just
mentioned, the spokes of the wheels
in the second picture (and in all the
pictures, for that matter) would be
in the same position they were in the
first picture, and so you could not
see that the wheel had turned.
Consider a simple proposition:
Take a wheel with only four spokes,
at right angles to each other. Start
the wheel turning and take your first
picture when two OF The spokes are
exactly verdical, the other two, of
course, being horizontal. When the
wheel has made a quarter of a turn
or revolution, take the second pic
ture-and SO on, a picture every
quarter turn. Project those pic
lures, and the wheel will appear to
be standing still, although you know
it was revolving when the pictures
were taken. Why?
Because every time a picture was
taken two of the spokes were vertical
and two horizontal. All the spokes
being alike, how can the y tell that
any change has taken place? And
the same is true, of course. no matter
how many spokes there are.
That, we think, sufficiently explains
why the wheels seem to stand still.
Why they should appear to turn
backward, while due to the same
cause, is a little harder to make
clear