The herald., 1896-10-25

- dust photographs and yet while this
= perhaps the first publication of the
strange phenomena, the publications
gwen are asserted by Prof. Thompson to
BE- simply based on hypothesis and are
subject to very decided change when
the scientises begin further experiments.
1t n to Mr.. E..lfsm ]. Hammer, a MEM
Der OF the Ar ican Institute of Elec-
4rtca1 Engir eers, that we owe the discov-
ery OF those eus1 IMAGES detailed by
Prof. Thompson.
Ar. Hammer h, ais workshop has a
pOrtrait formed OF flne dust upon pane
01 81ass. The circumstances pder which
r IVES obtained are peculiarly interest
ing. Mr.. Hammer happened to be in
some place where an artisan was re-
moving an Old photograph nom an old
fraxne. The glass which protected the
portrait exhibited fac eimile in dust on
the inner surface. The glass had not
been In contact with the photograph
because of a thick passe-partout sur
rounding the picture Neither was the
glass an old negative Photographic
plate.
Further test and inspection tended to
porVe tl1at the dust picture was executed
" some action of the heat or light Of the
st1n- Professor Benjamin F. Thomas, of
the University of the state of Ohio,
scarcely thinks that the result was due
70 convection, because the dust print
W1D 30 sharply defined. He thinks the
principle of the discharge of bodies by
light may be applicable uerhaps, but fur
tier experiment would be necessary as
= more secure foundation.
1T Is common" Prof. Thompson says.
ITO fInd the print of picture in book
upom the opposite page, being due mere
II to the pressure of the linked surface,
- n the art Of printing. This explana-
ton cannot be applied to the dust por-
trndts because there was no contact be-
tween the photograph and the glass"
1t would be well now that dust pho
to9fAphs exist to examine carefully the
Hl6se before removing an old picture.
Perhaps in the near future the world
VIII be enriched by many fine specimens
q these peculiarly produced images.
PHOTOS IN LAMPS
II. Hammer has also historical col
lootlOn of incandescent lamps, which
WuPe arranged on the shelves in glass
0xos standing obliquely in the sunlight
110ut an hour a day. After the lapse
" many months the very fine dust with
~ tNe case lodged upon the inner sur
fAoo of the glass In such manner as
~ produce oval dust figures cores
pond1ng somewhat to the shapes of the
I4f1pD and some of them appear after
t1tfoduciion. Prof. Thomas thought,
when the figures were inspected closely
ma the circumstances were known, that
~ sun and lamps acted as agents in
3nbtt formation.
~ to the correct explanation, the
u14tt4r has not been sufficiently dis
Gl1ood by scientists to enable him to
Eo10of the opinion of others, but 1t is of
cttUst IN connection with the Roentgen
y144 ond the discharge of electrified
&l1D Qf light AS matter Of course,
- 10r&aces Of the lamps would reflect
& ~ llght in such q way as to make bright
01Dnnovable, however, with the sun
~ the glass of the containing case,
- the latter were in any sense
4 ~ by negative atmospheric elec-
! n this hight would cause varia-
& 6Unt Of dust to be attracted ac-
~ ~ ne intenG1ty Of the rayu
"a III eml1n Also details = remark
s = sSrRsss,.s9ts I ss.s S..,Iss.S %sss ~ Y