New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1896-03-06
EXPERIMENTING WITH ROENTGEN RAYS

DISCOVERY THAT RADIATION is PROPAGATED
FROM TWO POINTS IN EACH TUBE.
South Bethlehem Penn. March (specaD.-In
the .ast ten days experiments on Rontgen's rays
have been made in the electrical laboratory of le-
high University under the direction of DR.. Alexander
Macfarlane with the assistance OF Messrs. kiinck.
Webb and Clark. instructors The object has been
TO test the physical properties of the rays. The
Crookes tube used in connection with an induction
coil. is cylinder 10 inches long and IL inches In
diameter. with a metal disk in the middle to form
the cathode and a wire at each end to form an
anode. When the two anodes Joined TO the
coil there is dark space on each SIDE OF the
cathode and both ends OF the tube are fuorescent;
when only one anode is connected only its end OF
the tube fuoresces.
To test the manner in which the R0ntgen rays
are propagated from the tube the following eX-
DC riments were made: Wire nails inch long
were driven vertically into ha.f-inch block OF
wood to form regular rows and columns ana
they all driven in so that their points just
pierced through the wood. The block Of wood with
the nails was laid plate-holder. and placed
at the end of the Crookes tube. SO as 10 be per-
perdicuar to the axis Of the tube. AS result the
Photographic plate showed single shadow for
each nail: right opposite the axis of the tube was
a mere dot. but from the axis the shadows are
Ike comets. the further out the longer the tails
and all these comets point straight at the dot in he
to what astronomers call radiant point in
meteoric shower; but here the meeors are all
heading toward not from, il.
The direction Of the rays at the side OF the tube
were next investigated. When the block with the
nails placed in vertical position Alongside the
tube, and both anodes connected to the coli. each
nail produced two shadows opposite the cathode
the shadows equal in length and intensity.
but toward each end Of the tube they were UNI
equal The two systems OF shadows indicate clearly
that the rays do not ralate from the tube as
whole. but thst they radiate only from the ends
where the luorescence Is When anode Is con-
nected only one system Of shadows Is obtained
The examination OF the two shadows OF nall
produced when the nall Is between two excited ends
shows how the exact location OF the nail may be
deduccd The point OF the nail was separated by
the slide from the senszed surface; consequently.
the two shadows do not meet but II they are pro-
longed the point OF Intersection gives the true POSI-
tion of the nail. This indicates how best TO two
radiant sources when search for the location OF a
bullet a needle In flesh Is made. In some pub
lished results experimenters represented hav
ing been puzzled by obtaining double sklagraphs OF
object. The reason Is that their plate was prob
ably exposed TO two distinct centres OF radao
To test whether the R6ntgen rays are refracted.
in the air; the two parts OF the shadow were In
straight line. showing that the rays through
the prism were not bent rom their original sonrce
The double Images which some expermenters have
got from rays passing through Iceland spar were
probably due 10 the radiation coming from two dis
tnct centres.
Tae reflection OF the rays was tested by placing
the block of nails where the divers could not
strike them. but the rays reflected from metal
plate would II these rays existed The Photographic
plate showed no impression 1t was found that a
red-hot iron wire was Opaque as cold iron
wire 49,. ,,x..ou 49,.
propagated in straight lines from the surface OF the
glass where the cathode rays strike. and that. as
has already been shown, they are neither reflected
nor refracted