River Falls journal. [volume] (River Falls, Pierce County, Wis.) 1872-2019, 1896-02-20
The New Photography at the State
University.

Work on the wonderful new process,
recently discovered in Germany of
photographing through Opaque mat
ter, has been carried on by DIR. l.. w.
Austin in the physical laboratory of
the University of Wisconsin during
the past week. Photographs of The
human hand have been taken in which
the bones show clearly in the midst of
the less distinct flesh. Another photo
graph shows pile of coins in closed
wooden box, the coins coming out dis
tinctly and even showing family the
overlapping parts, while the position
of the sides OF the box appears only as
hazy outline, though screw imbed-
ded in the wood is sharp and distinct.
A picture of a revolver shows the
spring and other parts as though the
wooden handle had been removed. A
welded iron ring was also photo
gIaphed, and the weld appears plainly
in the picture, although it is hardly to
be discovered in the ring itself. The
process of taking the pictures may be
briefly explained as follows: A closed
glass tube (Crookers' tube) is used from
which all but about millionth part
of the air has been withdrawn, and
which contains two metallic electrodes
which are connected with the poles of
an induction coil. The negative cleo
trode or kathode, in the tube, is in the
form Of round fiat disk, and when the
current is started rays Of. energy,
known as kathode rays, start out from
this. These rays show themselves in
the tube by the brilliant phosphor-
essence at the point where they strike
the glass. 1t was formerly supposed
that they ended here. but it is now
known that they pass through the
glass and make their presence known
outside by their action on the photo
graphic plate. The exact nature of the
rays is not understood, but it is sup
posed that they are vibrations in the
ether, perhaps somewhat like light,
though unlike light, they apparently
cannot be reflected or bent from
straight path. They pass through all
light substances like wood, paper, ETC.,
like light through glass, but they seem
to be stopped OF absorbed by all mat
term proportion to its density, SO that,
If any dense substance like metal is
placed in their path, it makes a
shadow of greater or less depth like a
partially Opaque object in the sun
shine and this shadow is shown on
the Photographic plate. In taking the
picture no camera is used, as the rays
would not be refracted by the tense.
The Crookes' tube is placed two or
three feet from the plate holder and
points towards it. The slide of the
holder remains closed, as it is trans
parent to the rays and the object to
be photographed is placed close
against the Slide The induction coil
which is connected with the tube is
put in operation for space of time
from a few minutes to an hour,
according to the density of the object
to be photographed and the strength
of the tube. At the end of this time
if the plate be developed as usual
distinct shadow picture Of the object
will be seen.
The new discovery, which is certain
ly one Of the greatest of recent years,
promises to be of vast practical value
in surgery, as by its means fractures
of the bones, bullets, calcareous de-
posits and the like :can be easily To-
Gated. The rays are so sensitive to
differences of thickness and density,
as WIS shown in the case Of the weld
in the ring before mentioned, that if
Crookes' tubes of sufficient power can
be made they can perhaps be used to
detect flaws in metal castings and thus
prove of the greatest value to the en-
gineer.