The morning news. [volume] (Savannah, Ga.) 1887-1900, 1898-03-16

der the light of single vacuum tube al a
distance of five feet with an exposure
of five seconds.
Every wrinkle in the face of the man is
clearly shown. The hairs of the beard and
the eyelashes are distinct. The effect is
almost startling. The face seems to stand
out from the paper. This photograph was
taken, too. without the discomfort to the
subject which attends the use of the flash
light.
The most remarkable photograph is that
of the hand of Tesla. 1t was made by
the light of a single improved vacuum
tube of 1000 candle-power, at a distance
of four feet, after an exposure of two Sec
onds. The lines of the hand stand forth
so clearly that the palmist may read them
with the greatest care. Every detail is re-
produced with microscopic accuracy. The
veins of the wrists and the fine lines upon
the cuticle are faithfully shown. The tex
ture of the inventors coat is shown in
several inches of the sleeve and the linen
threads of the cuff are almost distinct
The shadows about the wrists and fingers
give the impression that you are looking
at hand of flesh and blood.
Another photograph is that of an open
book upon electricity supported by two
hands. This was done by a vacuum tube,
at a distance of four feet, with an ex-
posture of two seconds.
Mr.. Tesla makes his announcement in
a letter 10 the editor Of the Electrical Re-
view. In speaking of his experiments in
photography he says:
The photographs shown were taken by
tube having radiating service of .,bout
200 square inches. The frequency of the
oscillations, which were obtained from
an Edison direct-current supply circuit
L estimated to be about 20OO.0O a second.
The Illuminating power of the tube up
proXimated about 1000 candles, and the
exposures ranged from two to five sec
onds, the distance of the object being four
to five feet from the tube. 1t might be
asked why, with SO high an Illuminating
power, the exposures should not be in
Simultaneous. / would not undertake to
satisfactorily answer this question which
was put to me recently by a scientific man.
whose visit to my laboratory 1 still vivid
ly recolect.
Likenesses can, of course, be obtained
with instantaneous exposures, but it has
been found preferable to expose longer
and at a greater distance from the tube
The results SO far obtained would make
it appear that this kind of light will be
of great value to photography, not only
because of the fineness of the lines, but
also because the artist will be able to ex-
actly adjust the conditions in every ex-
pertinent so as to secure the best result,
which Is impossible with ordinary light
He will thus be made entirely independent
of daylight and will be able to carry on his
work at any hour, night or day. 1t might
also be of value to the painter though
its use for such purposes 1 will consider
problematical
Another development Of Mr.. Tesla vac
uum tube which will prove of incalculable
value concerns lighthouses. 1t is we'll
known that it is difficult to secure a light
which will penetrate fog. 1t is believed
that light from the vacuum tube will
eventually be used for this purpose. 1t IS
likely that practical experiments will soon
be made in some lighthouse on this coast
for the purpose Of demonstrating the prac-
ticability of Mr.. Teslas' ivention.
by producing tubes of much greater
candle power" says Mr.. Tesla In his let
ter, speaking of progress in electric light
ing, "a notable improvement in this re-
spect was effected and this advance
prompted me to further efforts in this di-
rection, which finally resulted in the pro
duction of tube of hundreds, and even
thousands, of ordinary vacuum tubes. That
is more, believe that am far from hav-
ing attained the limit in the amount of
light producable, and believe that this
method of illumination will be eventually
employed for lighthouse purposes. This
probably will be considered the oldest and
most unlocked for development of the vac
uum tube"
Mr. Tesla also says in his letter that
he finds that from an ordinary vacuum
tube, not much greater in volume than
an ordinary incandescent lamp, about the
same amount Of light is produced as from
the incandescent lamp without any over
heating.