Evening star., 1896-02-22
ROENTGEN'S DISCOVERY
Prof B. n. johnson Makes Successful
Experiment With < Rays.
A Block of Aluminium Proves Trans
Glass IL Nearly Opaque.

Prof. H. M. johnson Of the Eastern High
School. IN common with scores OF other
scientists who are keenly Interested in the
peculiar discovery made by DR.. Roentgen,
succeeded yesterday in making a very dis
tlnct demonstration of the power Of the X
or unknown rays to penetrate various SUBJ
stances hitherto regarded as opaque. Hav-
Ing In his charge. perhaps the only Crookes'
tube In Washington, which he had bor-
row'ed a fortnight ago of the Corcoran
Scientific School for the purpose OF demon
strstions before his class In the Eastern
High School, he undertook several expert
ments In the line of DIR. Roentgen's discov-
cry.
Upon an ordinary sensitized plate, in q
plato holder laid fiat on a table. he put a
humber of objects, among them a pair Of
eyes iasses. a steel keyring, a copper cent, a
silver dime aid piece of aluminium about
threeeighJhs of an inch thick. Above this
The 'rockeS' tube was suspended and q cur
rent Of electricity from u six-celi battery
was Iasssd through the tube. The result
lEg pate contained a very well defined
Silhouette of the copper cent, the eyeglasses
ano tca steel ring The silver dime was but
faintly outlined and the aluminium was al
most without place on the plate. showing
that to tho rays aluminium has very little
opacity. and silver but slittle more, while
SsSaSS. Ep4'itI 6HO SteGl are CO1npdfatiEely
tnnperv,ous to them. The prints from the
plate thus made were made by Prof. Smiley
at the National Museum.
This Crookes' tube which used" said Dr.
Johnson. us an excellent one Of very high
vacuum. A singular feature of the expert
ment was that the current Of electricity
seemed to pass from the negative pole
obliGnely across the tube. a distance of
about an inch and half or two inches, in
stead of toward the positive pole, some five
inches away at the other end Of the tube
1t also appears that there Is somewhere a
Certain strength of current which will pro-
dnce the best results In experimenting with
the unknown rays. and that a strong cur
rent will often utterly defeat the object of
the experiment. The current used had a
spark about an inch long. A stronger cur
rent was less satisfactory.
''Sooaer or later l think 1t will appear IL
the theory now advanced is correct, that
these unknown rays vibrate longitudnaliy
instead OF transVeI Sely, as has always been
hitherto assumed. that there is ratio be-
tween the length of the vibration in the cur
rent and that Of the X rays. On the other
hard, too. there n ust, sooner or later, no
doubt. appear a II athematical relationship
between the molecular condition of sub
stances and these rays Why the rays
should penetrate aluminium so easily and
not glass. which to the solar ray Is trans
parent, it is lard to understand unless 1t
can be accounted for in the theory that
there is a certain mathema teal relationship
a
In the unknown rays.
Certainly Ii is a wonderful discovery
and It has at once practical application
TN surgery ard medical science which
makes It Of the highest Importance. 1t will
not be long before we shall have tables of
opacity showing precisely the relative
tran spareney of a large list OF objects or
d!nari.y regarded as Opaque. and actually
SO to the solar ray. Whether this new dis
covery will have any value in other fields
of science is row only 4 matter OF conjec-
ture. hive been asked If it could be used
IN astronomy. That science has so far
made use only Of the visible solar ray and
by the use of the spectroscope as we all
know. has made marvellous discoveries with
regard to other worlds than ours. / do not
now see how use can be made of these X
rays in astronomy. yet it may be DONE for
1t certainly would be no more surprising
than the discovery in itself. There Is one OBJ
servaticn I would like to make in rega rd
to DIR. Roentgen's remarkable discovery
and thac Is that when in his modesty he
names these unknown rays with the alge-
braic term 'X'' he is entirely too unassum-
Ing, for in a discovery of such great human
Importance it Is no more than just that his
own name should be perpetuated by calling
these the 'Roentgen rays"