The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1897-12-12

and blurred lines are due TO the mutual
action Of the primary and reflected
waves. This photograph may help us
to realize the reflection of sound waves
in air. We knew that in order to hear
all the sound produced the listener
ought to be in full view of the orches-
ira. because some sound waves are un-
able to come round corners and are re-
fiected away from the listener, who is
situated behind some obstacle.
CURIosITIEs OF WAVE MOTION.
~Marconi waves are endowed with
such wonderful properties that they
are able TO go through brick walls and
round ali sorts of corners. Roentgen ray
waves again can so through great
many substances which are opaque to
ordinary light waves. In the fifth pho
tograph we have another instance of
reflected mercury ripples, for Mr.. Vim
cent has here arranged q shallow cir
cular reflector. We set at the corners
of this the same blurred circles we saw
in another illustration and a. series of
lenses arc seen streaming away from
the reflector. The scientific mind calls
these s'confocai elipse and confocal
hyperbolas,' but though the lay mind
cannot grasp the significance of these
rippleS, it can at least appreciate the
beauty of the photographs and the in
genuity of the savant who took them.
Our sixth illustration shows the rip
pie breaking against a semi circular
reflector with mercury. The reflected
ripples take the curious shape of
straight lines in the middle, but are
bent outward from the reflector to-
ward the ends, illustrating Spherical
alteration"
Number. seven shows some queer pat
terms. Instead Of using the tuning
tf OIL he bo5
We're originated by the agitation OF a
slip Of cover glass, one s$ide OF which
is made to din into the mercury; they
are reflected from the shallow circular
mirror. The interference effects are
seen in the blurred waves at the bottom
of the picture and if the photograph be
carefully locked into many curious rip
pie forms will be observed due to re-
Election. To students of natural phil
osophy, these photographs should be
of great assistance IN their study of
physical problems.
The eighth and last picture gives us
q very interesting pattern. The ripples
are set up as in the previous photo
graph and are reflected at an angle of
about 10 degrees from a straight edge.
The long black mark running from
one end of the dipping edge of the slip
of cover glass to the corner of the print
/ is due to depression in the surface
caused by a floating needle put there
to screen off the circular waves coming
from the end of the strip of glass. We
see to what straits the ripples are here
put They cannot pursue the even tenor
Of their way, but are so harassed by
obstacles that they take the most eX-
traordinary forms, at which the mind
cannot fail to marvel
In conclusion it may be said that
these photographs taken by Mr.. Vim
cent present analogues of the greatest
service in demonstrating the phenom-
ena of acoustics ard optics, for they
are infinitely superior to geometrical
pictures drawn by instruments. We
have all been greatly interested in the
wireless telegraphy" experiments of
Signor Marconi and others and we
know that his invisible kilograms are
1 carried by extremely rapid waves in
the ether. These photographs help us
to realize how such things can be, and
( the wave theory of light becomes clear
when we examine these mercury rip
! pies.