The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1898-01-12
EQUAL TO SUNLIGHT.
TesIa's Perfected Vacuum for Taking
Photographs at Night.

NikOla Tesla, the ~Well-knOWn electrician,
announces an important discovery to-day in
the Electrical Review He says that he has
perfected vacuum tubes of such high ilum-
mating power that they may be used in
lighthouses, and that they will enable the
photographer to work by night as well as
by day. He even suggests that by means
of this light the painter may be able to dis
tinguish colors as we'll at night as he can
by the clear, soft light of day.
The result which Mr.. Tesla has attained
represents several years of patient expert
menting. His work was somewhat retarded
by the burning OF his laboratory in 1898. He
is not ready yet to describe his invention in
detail. He promises to do so soon. He al
ways speaks in a conservative way OF his
discoveries. / called yesterday at his labor
atory. His bearing was one of great e!ation.
The results which Mr.. Tesla has attained
have been achieved by the use of his
vacuum tubes and his oscillator. The light
which he is able to produce by this means
is as bright as that of the monday sun. By
it's use every line of the object photographed
may be made to stand out clearly end dis
Mr.. Tesla has taken several photographs
by this light, which are reproduced in the
ographs yesterday at the office of the pub
LEGATION. Half-tone engraving cannot begin
to do justice to the extreme c~learness and
delicacy of these photographs. 1t is posi-
BILE to give only q suggestion of the clear
ness of the original in a picture, such as IS
ton. The accompanying portrait is from
one of the half tones. The original photo
graph was made under the light of a single
vacuum luDG at Il QlSIdIlCe u llt6 lSSl, Will
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 al
most startling. The face seems to stand out
from the paper. The photograph was taken,
too. without the discomfort to the subject
which attends the use of the flashlight.
The most remarkable photograph is that
of the hand of Tesla. 1t was made by the
light of a single improved vacuum tube of
one thousand candle power, at a distance of
four feet, after an exposure of two seconds.
The lines of the hand stand forth so clearly
that the palmist may read them with the
greatest care. Every detail is reproduced
with microscopic accuracy. The veins of the
wrists and the fine lines upon the cuticle
are faithfully shown. The texture 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 a 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 exposure of
two seconds.
Mr.. Tesla makes an announcement in a
letter to the editor of the Electrical Re
view. In speaking Of his experiments in
photography he says:
1.-The photographs shown were taken by a
tube, having a radiating surface of about
two hundred square inches. The frequency
of the oscillations, which were obtained
from an Edison direct-current supply cir
cult, I estimated to be about two million a
second. The illuminating power of the
tube appropriated about one thousand
candles, and the exposure ranged from two
to five seconds. the distance of the object
being four to five feet from the tube. 1t
might be asked why, with so high an illu-
minating power, the exposures should not
be instantaneous l 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 wildly
recollect.
Likeness can, Of course, be obtained with
instantaneous exposures, but 1t 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 kin of light will be of great value in
photography, not only because of the fine
ness of the lines, but also because the artist
will be able to exactly adjust the conditions
in every experiment so as to secure the best
result, which is impossible with ordinary
pendent of daylight and will be able to car
ry on his work at any hour, night or day.
1t might also be Of value to the painters,
though its use for such purposes L still con-
slider p~roblematical."
Another development of Mr.. Tesla's vacu-
um 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 prac-
tical experiments will soon be made in some
lighthouse on the coast for the purpose of
demonstrating the practicability of Mr..
Tesla'S invention.
by producing tubes Of much greater can
ole power, says MI. IeSla IN his letter,
speaking of progress in electric lighting, "a
notable Improvement in this respect was eff
fected, and this advance prompted me to
further efforts in this direction, which fin
ally resulted in the production of a tubs of
an Illuminating power equal to that of hum
dreds, and even thousands, of ordinary
vacuum tubes. What is more, I believe that
I am far from having attained the limit in
the amount of light producible, and believe
that this method of illumination will be
eventually employed for lighthouse pur-
poses. This probably will be considered the
oldest and most unlocked for DEVELOPMENT
of the vacuum tube"
Mr.. Tesla also says in his letter that he
finds that from an ordinary vacuum tube,
nary incandescent lamp, about the same
amount of light is produced as from the
~incandescent lamp without any overhead
ing.