New-York tribune., 1896-01-19
Grtra Cirsv.t

drv-pla:e with a ihin sheet OF mica lnterposed. Al
the back OF the g'ass there round piece OF
tnfoil or the same size the coin. and directly
opposite IT, This peculiar sandwich completed
by applying hard rubber plate 10 the tlnfoil. anu
book OF wood to the coin. These were all pressed
firmly together, and the edges protected from any
light. that the package could have been tax n
out into the open sunlight without producing any
effect on the sensitive film OF the plate. How
eve-. ii WAS not taken out, but Kept IN daiH
room where the discharsing apparatus OF an cleo
trical m achne was situated The brass Knobs or hS
dev.cc about one-sxteenth OF an inch apart,
and a cOne:ant stream OF little sparks from one
10 the other maintained for an hour. Proies-
sor Sanford believes however. that he completely
excluded all light produced thereby from his pho-
tographc plate. TO the rods each side OF the
spark-gap were attached copper wires. one being
connected with the rear Ok the coin. and the other
20 the unfol on the back OF the Photographic
cla:,. ANY electri, impulse proceeding from one
rod ot the discharge along this new circuit TO the
other roc, It will be secn obliged to cross an
other gap In order get from the coin 70 the tin
fol. Il would have been necessary for the waves OF
energy penetrate mica OF the best lnsula tors
in the word). the senstIzed gcatne film on the
face o: the Photographic plate. and then the glass
Of that plate. The rest OF the route was metallic
A. the end OF hour the shut on.
the plate carefull.' removed and ''dcveloped ana
an image OF the co!n was found impressed thereon.
Those portions OF the film opposite the raised feat
OF the cOr most acted upon. that a
print from the negative (and The Tribune has had
for years. rcproduces the relief in white
and the depressed portions in black.
As early as 1881 Professor Sanford had produced
images with a direct current on bromide paper
inserted between The terminals o, hs wires. the OBJ
ject photographed being attached ot them.
He also wrote on PHOTOGRAPHIC pate with the
end OF a wire which was connected with the ter
a-ssff Ia. 49,
latter Instance. when developed" showed the char
acters written thereon. Bu, the experiment de-
SCRIBE in deiai. was an attemp' 20 utilize the
electric oscillations known as "Horizian waves,
which are excited In a sor; o' SIDE crcuI, when
a "disruptive discharge" Is occurring In the prin-
cipal circuit. Some scientists nj frs; questioned the
accuracy OF Professor Sanfords explanation. hut
he repeated the test with other Insulating material
than mica between the coin and sensitive film.
When he used parafine. shellac or cbonitr IN thin
layers. he succeeded Qually we'll The image be
came indstlnci however ~ hs used II thick ms
lator.
The Pao Alto experiments become more in,eli-
gib'c when recalls the comparatively recent but
now historic researches of Heinrich Hertz the gifted
young physicist. Of Bonn University. who d-l
year or lie proved that the class % sym
pathetic vibrations Just referred 10 possess some
very strange properties Such ccu,d hr d
verte1 from their by peculiar kind Of PRISM
10 verify Clerk Maxwers grea; electro ma gnci.c
theory of light But what was most wonleriui Of
all, ana what has possible bearing on the subject
In hand. was the discovery mat the iIcrz!an wlyos
will pass with great freedom through ordinary in
sula tors. Ike glass. wood. dry ar AMI ooih while
such materials good conductors OF electricity
Onetll. carbon and waterp obstruc' the passage Of
these V!brai ons The novice In such ma tsrs wouli
probably call the Hertzan waves a modified kind
OF electricity bat some experts discourage the use
OF such an expression. They insist that we have
here a form OF energy distinct from electricity
light and heat are.
Professor RGntgen employed somewhat d!fferen.
apparatus. as well different subjects for pho
toFraphy For hfteen OF twenty yeors an elaborate
series OF experiment. have been conducted by "A
number OF distinguished electricians ami chemists
TO discover the behavior OF electricity when pa s,lns
through gases, and especially rarcheI gases brief
a.iusion 10 Professor ROntgen. In Thomsons Re
cent Researches" page 81. shows that he ha 4.
taken part IN these invc-tigailOns and has thsr,-
fore. been long familiar with the. attendant me.
nomena. In many o. the experiments In question
electricity WAS discharged through a closed tube
into each crd OF winch was sealed wire or ,ny